vaccination

Definition

Vaccination is the use of vaccines to prevent specific diseases.

Description

In addition to those discussed above, vaccines are available for preventing anthrax, cholera, hepatitis A, Japanese encephalitis, meningococcal meningitis, plague, pneumococcal infection (meningitis, pneumonia), tuberculosis, typhoid fever, and yellow fever. Most vaccines are given as injections, but a few are given by mouth.

Some vaccines are combined in one injection, such as the measles-mumps-rubella (MMR) or diphtheria-pertussis-tetanus (DPT) combinations.

— Larry I. Lutwick, MD

1. Inoculation with a vaccine in order to protect against a particular disease.
2. A scar left on the skin by vaccinating.

Key Terms: Adjuvant, Allogeneic, Antigen, Antigen presenting cell, Autologous, Cytokine, Dendritic cell.

Definition

A cancer vaccine is a method of treating the disease involving administration of one or more substances characteristic of the cancer, called antigens, often in combination with factors that boost immune function. This induces the patient's immune system to attack and eliminate the cancerous cells.

Purpose

Unlike traditional vaccines for infectious diseases, at this time cancer vaccines are not given to prevent the initial development of cancer. Instead, cancer vaccines are a method of treating cancer that has already occurred and are given to patients already diagnosed with cancer.

As a cancer treatment method, the ultimate goal of most cancer vaccines is the elimination of tumor or cancerous cells from the body. Other vaccines are given after the use of more traditional treatments, such as chemotherapy, radiation, or surgery, with the aim of suppressing the recurrence of the cancer.

Precautions

No vaccine has yet been approved by the Food and Drug Administration (FDA) for the treatment of cancer. Accordingly, vaccines are not standard treatments and other more traditional treatments should be investigated first. Vaccines are available only through participation in clinical trials. Each trial has its own criteria that can limit who can participate. However, many cancers have a current trial for one or more types of vaccines. The American Society for Gene Therapy states that as of late 2000, vaccines were the most common approach to gene therapy being studied by researchers.

Most vaccine trials test the response of the disease with and without the vaccine or the effect of substances added to the vaccine, called adjuvants. Such trials usually only accept patients who have already tried the standard treatment methods. Others test a standard treatment method with and without the addition of the vaccine. A very few compare the standard treatment to the vaccine.

Looking at cancer vaccines overall, this treatment method has been more successful eliminating very small tumors rather than the getting rid of a large tumor load. So if the size of the tumor is significant, a more realistic goal is to shrink the tumor and reduce its effect on the patient's body, rather than total elimination of the cancer.

The complexity of the human immune system has made it very difficult to develop an effective vaccine. Tumors have strategies to evade detection by the immune system. Most notably, they mimic the outward appearance and antigens of the body's own cells. The immune system's built-in lack of response against "self" allows the tumor to escape notice by the body. Now fully aware of this phenomenon, researchers are working to develop methods of circumventing this problem to develop a highly effective vaccine system.

Description

There are three general types of cancer vaccines, those that use whole tumor cells, those that use only one or more substances derived from the tumors, or those that administer primed cells from the patient's immune system.

Whole Cell Vaccines

Whole cell vaccines are autologous when they contain only inactivated tumor cells from the patient's own tumors. The cells have been isolated from the tumor and made to grow in the laboratory, a process known as creating a cell line. Allogeneic whole cell vaccines are made from inactivated tumor cells isolated from one or more other people. The main advantage to autologous vaccines is the direct relation between the vaccine and the tumor target. However, because of the screening of self antigens away from a body's own immune system, immune response to tumor antigens in autologous whole cells vaccines can be low.

Allogeneic vaccines avoid some of the problems of autologous vaccines. First, cell lines do not have to be created for each patient, a labor-intensive process that can have highly variable results. Second, the same vaccine can be given to all patients, making the response to the vaccine more predictable. Third, a use of a pool of tumor cells can increase the possibility of having the full repertoire of the tumor antigens in the vaccine. This helps to overcome the ability of tumor cells to escape notice by the immune system. Finally, by using well-characterized cell lines, it is much easier for the researcher to add genetic modifications that increase the immune system's response to the cells.

Isolated Antigen Vaccines

There are many kinds of vaccines that deliver only a portion of the tumor cell that will elicit an immune response, called an antigen. Some antigens are unique to a cancer type, some are unique to an individual tumor, while a very few are found in more than one cancer type. For example, vaccines against telomerase and human chorionic gonadotripin (hCG), two proteins produced by many cancers, have been developed, raising hopes for the development of a universal cancer vaccine.

The most common kind of antigen used in cancer vaccines is a protein or a part of a protein. The protein can actually be isolated from the tumor cells, or more commonly, produced in large quantity using genetic engineering techniques. When a part of a protein is used, experimental efforts generally preceded the vaccine production to determine what parts of the protein were often the target of immune responses. Parts of proteins that elicit immune responses are called epitopes.

Antigens do not necessarily have to be proteins. Immune responses are also mounted against the carbohydrate (sugar) molecules present on the surface of the proteins. Tumor proteins can have unusual carbohydrate structures that set them apart from cells from normal tissue. Carbohydrates are also found in abundant numbers on the surface of the tumor cells. Accordingly, researchers have developed cancer vaccines that combine the tumor-characteristic carbohydrates anchored on protein bases. These vaccines are being tested for their ability to reduce the recurrence of prostate cancer.

Vaccines can also contain the naked genetic material encoding the protein (either deoxyribose nucleic acid, DNA, or ribose nucleic acid, RNA). After the genetic material gains entry to the cell, the cellular machinery uses it to produce the antigen and an immune response is mounted against it. Animal studies have found that these types of vaccines are very dependent on the particular antigen and the mode of administration of the vaccine. A unique method of delivery used with DNA or RNA vaccines is the coating of tiny gold beads with the genetic material and shooting the beads into the skin.

Genetically engineered viruses can also be used to bring the DNA or RNA into the cell. When used in this way the viruses are called viral vectors. One example of a viral vector currently being used as a cancer vaccine is one based on the adenovirus. When viruses are used as vectors they have been altered to no longer cause disease, but they do retain the ability to infect human cells. Instead of making new viruses, the infected cells make the desired antigen, and the body will respond against it. Viral vectors can also carry the genetic instructions for factors, called cytokines, which boost the immune system's response to the antigen.

Antigen-Presenting Cell (APC) Vaccines

Vaccines can also be made that contain cells from the patient's own immune system, in particular antigen-presenting cells (APCs). These cells play a central role in the development of an immune response against a particular antigen. Specifically, APCs ingest the antigen and present them to the T cells, a type of immune cells responsible for targeting and killing cells seen as foreign to the body. If T cells are exposed to the antigen by an APC, as opposed to seeing the antigen on the cell itself, they are more strongly activated. That is, more T cells that specifically attack that antigen are produced and the immune response against the foreign cell is stronger.

Dendritic cells are a type of APC that is most effective in activating T cells. For this reason, they are often the kind of cells used in APC vaccines. Unfortunately, the number of dendritic cells circulating in the blood at any one time is relatively low. However, new techniques have been developed that allow that small number of dendritic cells to be isolated and then stimulated outside the body to result in a usable number. During stimulation, the dendritic cells are exposed to the tumor antigen, a process known as priming. Thus, when injected into the body, the dendritic cells are primed to recruit large numbers of T cells specific against the tumor antigen.

Cyokines and Adjuvants

Because of the ability of tumor cells to escape detection by the immune system, an important component of many cancer vaccines is the addition of biological factors or chemical adjuvants to help boost immune response. One type of adjuvant is a cytokine, a factor normally produced by cells of the immune system to help recruit cells to the site of the foreign cells or help T cells function. Some examples of cytokines used in vaccines are granulocyte/macrophage colony stimulating factor (GM-CSF, or sargramostim), the interleukins (especially IL-2), the interferons (INFs), and tumor necrosis factor alpha (TNF-α).

Adjuvants are chemical additions to vaccines that help boost the response to the contained cells or antigens. Adjuvants are derived from a variety of sources and can be isolated from animals, plants, or are synthetic chemical compounds. Several adjuvants in use with cancer vaccines are keyhole lympocianin (KLH, derived from shell-dwelling sea animals), incomplete Freud's adjuvant (IFA, mineral oil and an emulsifying agent), and QS-21 (a chemical derived from the soapbark tree).

Administration

The particular administration method and schedule will vary from clinical trial to clinical trial. Administration methods can include intradural (injection within the skin), subcutaneous (injection below the skin), injection into the lymph nodes, or intravenous (injection into the veins). Typically, vaccines are administered as a series of several doses (initial challenge and boosters). Many clinical trials utilize various administration methods and timing strategies in order to try to determine the best means of inducing an anti-tumor immune response.

Preparation

Before enrolling in a clinical trial, patients should discuss the potential benefits and risks with their doctor. Clinical trials can be located by contacting the research institutes directly or by searching the Internet. A particularly good site for getting information about clinical trials for cancer treatment is run by the National Cancer Institute ().

Aftercare

One of the most striking advantages of vaccines compared to other cancer treatments is the relatively low incidence of side effects. Particularly if IFN is used as an immunoadjuvant, patients sometimes experience flu-like symptoms. However, other than some soreness at the site of injection, vaccine patients generally have no adverse reactions to this kind of treatment.

Risks

The greatest risk with cancer vaccines is that there will be no immune response and the treatment will be ineffective. Although serious adverse reactions to the antigens, such as the attack of healthy cells, are theoretically possible, these fears have not materialized. Other than some mild adverse reactions, such as fever and redness of the skin at the injection site, vaccine treatment appears relatively low-risk in the traditional sense.

Normal Results

Based on a review of published clinical trials as of 2000, normal results for this treatment is, unfortunately, little or no effect. Although a response by the immunized patient's T cells against the tumor is often documented by testing, the effect on disease is generally marginal. These results could be at least partially due to the selection process for patients in the trials, who are often suffering from late-stage cancers.

Abnormal Results

For each trial, there are a small percentage of patients who have complete, partial, or mixed response to the vaccine. Others show a stabilization of the disease where deterioration of condition would be expected. As

Questions to Ask the Doctor

• Have all the standard treatment methods for my cancer been tried?
• Is there a vaccine in clinical trials for my kind of cancer?
• Do I fulfill the requirements necessary for the clinical trial for this vaccine?
• Has this vaccine been tried on human patients before?
• If so, what were the results?

traditional treatments were often unsuccessful with these patients, these results are significant. However, the very low rate of success underscores the complexity of the human immune system, the number of variables in the vaccine method, and the amount of research that will need to be done to develop an effective vaccine treatment for this disease.

Resources

Books

Restifo, Nicholas, et al. "Therapeutic Cancer Vaccines." In Cancer Principles & Practice of Oncology, edited by Vincent DeVita, et al. Philadelphia: Lippincott Williams & Wilkins, 2001, pp. 3195–217.

Periodicals

Bocchia, Monica, et al. "Antitumor Vaccination: Where We Stand." Haematologica 85 (November 2000): 1172–206.

Monzavi-Karbassi, B., and T. Kieber-Emmons. "Current concepts in cancer vaccine strategies." Biotechniques 30 (January 2001): 170.

Other

"First Potential Universal Cancer Vaccine Shows Promise In Lab." ScienceDaily Magazine. 30 August 2000. [cited April 12, 2001 and June 28, 2001]. .

"Treating Cancer with Vaccine Therapy." CancerTrials. July 20, 1999. [cited April 12, 2001 and June 28, 2001]. .

—Michelle Johnson, M.S., J.D.

Active immunization against a variety of microorganisms or their components, with the ultimate goal of protecting the host against subsequent challenge by the naturally occurring infectious agent. The terms vaccine and vaccination were originally used only in connection with Edward Jenner's method for preventing smallpox, introduced in 1796. In 1881 Louis Pasteur proposed that these terms should be used to describe any prophylactic immunization. Vaccination now refers to active immunization against a variety of bacteria, viruses, and parasites (for example, malaria and trypanosomes). See also Smallpox.

Implicit within Jenner's method of vaccinating against smallpox was the recognition of immunologic cross-reactivity together with the notion that protection can be obtained through active immunization with a different, but related, live virus. It was not until the 1880s that the next immunizing agents, vaccines against rabies and anthrax, were introduced by Pasteur. Two facts of his experiments on rabies vaccines are particularly noteworthy.

First, Pasteur found that serial passage of the rabies agent in rabbits resulted in a weakening of its virulence in dogs. During multiple passages in an animal or in tissue culture cells, mutations accumulate as the virus adapts to its new environment. These mutations adversely affect virus reproduction in the natural host, resulting in lessened virulence. Only as the molecular basis for virulence has begun to be elucidated by modern biologists has it become possible to deliberately remove the genes promoting virulence so as to produce attenuated viruses.

Second, Pasteur demonstrated that rabies virus retained immunogenicity even after its infectivity was inactivated by formalin and other chemicals, thereby providing the paradigm for one class of noninfectious virus vaccine, the “killed”-virus vaccine.

Attenuated-live and inactivated vaccines are the two broad classifications for vaccines. Anti-idiotype antibody vaccines and deoxyribonucleic acid (DNA) vaccines represent innovations in inactivated vaccines. Recombinant-hybrid viruses are novel members of the live-virus vaccine class recently produced by genetic engineering.

Because attenuated-live-virus vaccines reproduce in the recipient, they provoke both a broader and more intense range of antibodies and T-lymphocyte-associated immune responses than noninfectious vaccines. Live-virus vaccines have been administered subdermally (vaccinia), subcutaneously (measles), intramuscularly (pseudorabies virus), intranasally (infectious bovine rhinotracheitis), orally (trivalent Sabin poliovirus), or by oropharyngeal aerosols (influenza). Combinations of vaccines have also been used. Live-virus vaccines administered through a natural route of infection often induce local immunity, which is a decided advantage. However, in the past, attenuated-live virus vaccines have been associated with several problems, such as reversion to virulence, natural spread to contacts, contaminating viruses, lability, and viral interference. See also Animal virus; Virulence; Virus classification; Virus interference.

Noninfectious vaccines include inactivated killed vaccines, subunit vaccines, synthetic peptide and biosynthetic polypeptide vaccines, oral transgenic plant vaccines, anti-idiotype antibody vaccines, DNA vaccines, and polysaccharide-protein conjugate vaccines. With most noninfectious vaccines a suitable formulation is essential to provide the optimal antigen delivery for maximal stimulation of protective immune responses. Development of new adjuvant (a substance that enhances the potency of the antigen) and vector systems is pivotal to produce practical molecular vaccines. See also Antibody; Antigen; Immunity.

Any injection of attenuated microorganisms, such as bacteria, viruses, or rickettsiae, administered to induce immunity or to reduce the effect of associated infectious diseases.

Definition

Vaccination introduces a vaccine into the body to produce immunity and prevent specific diseases.

Description

Many diseases that once caused widespread illness, disability, and death are now prevented by vaccines in developed countries. Vaccines are medicines that contain weakened or dead bacteria or viruses. When a child receives a vaccine, his or her immune system responds by producing antibodies, substances that weaken or destroy disease-causing organisms. When the child comes in contact with live bacteria or viruses of the same kind that are in the vaccine, the antibodies prevent those organisms from making the child sick. Vaccines also stimulate the cellular immune system. In other words, the child becomes immune to the disease the organisms normally cause. Building immunity by using a vaccine is called immunization. Childhood immunizations are safe and remain the most effective way to prevent disease.

Vaccines contain antigens (weakened or dead viruses, bacteria, and fungi that cause disease and infection). When introduced into the body, the antigens stimulate the immune system response by instructing B cells to produce antibodies, with assistance from T-cells. The antibodies are produced to fight the weakened or dead viruses in the vaccine. The antibodies "practice" on the weakened viruses, preparing the immune system to destroy real and stronger viruses in the future. When new antigens enter the body, white blood cells (called macrophages) engulf them, process the information contained in the antigens, and send it to the T-cells so that an immune system response can be mobilized.

General Use

In the early 2000s, children in the United States and in other developed countries routinely have a series of vaccinations that begins at birth. Vaccinations in children began about 1900 with the smallpox vaccine. In 1960 there were only five vaccines in eight shots. The number of vaccinations children receive has steadily increased since that time. As of 2004, children receive 11 different vaccines given in up to 20 shots by age two years. Given according to a specific schedule, these vaccinations protect against hepatitis B; diphtheria, tetanus, pertussis (whooping cough) (DTP); measles, mumps, rubella (German measles); varicella (chickenpox); polio; pneumococcus; and Haemophilus influenza type B (Hib disease, a major cause of spinal meningitis) and, in some states, hepatitis A. This series of vaccinations is recommended by the American Academy of Family Physicians, the American Academy of Pediatrics, and the Centers for Disease Control and Prevention and is a requirement in all states before children can enter school. States make exceptions for children who have medical conditions such as cancer that prevent them from having vaccinations, and some states also make exceptions for children whose parents object for religious or other reasons.

Several vaccines are delivered in one injection, such as the measles-mumps-rubella (MMR) and diphtheria-tetanus-pertussis (DTP) combinations.

Vaccines are used in several ways. Some vaccines, such as the rabies vaccine, are given only when a child comes in contact with the virus that causes the disease, such as through a dog bite.

Recommendations for other vaccines and immunobiologic medicines depend on the child's health status or area of world where the family might travel. Such treatments are vaccine or immune globulin for hepatitis A, typhoid, meningitis, Japanese encephalitis, and rabies.

In addition the uses discussed above, vaccines are available for preventing anthrax, cholera, plague, tuberculosis, and yellow fever. Most vaccines are given as injections, but a few are taken orally.

The administration of vaccines to meet travel requirements should not interfere with or postpone any

of the routine childhood immunizations. If necessary, the routine immunization schedule can be accelerated to give as many vaccines as possible before departure. Decisions about vaccinations for children with chronic illnesses are made with the child's doctor.

Parents who are planning to travel with children to another country should find out what vaccinations are needed. Some vaccinations may be needed 12 weeks before the trip, so getting this information early is important. Many major hospitals and medical centers have travel clinics that provide this information. The traveler's health section of the Centers for Disease Control and Prevention also has information on vaccination requirements.

A vaccination health record helps parents and healthcare providers keep track of a child's vaccinations. The record should start when the child has his or her first vaccination and should be kept up-to-date with each added vaccination. While most doctors follow the recommended vaccination schedule, some flexibility is allowed. For example, vaccinations scheduled for age two months may be given anytime between six to ten weeks. Slight departures from the schedule do not keep the child from developing immunity, as long as all the vaccinations are received close to the right times.

Precautions

Vaccines are not always effective, and there is no way to predict whether a vaccine will "take" in any particular child. To be most effective, vaccination programs depend on the whole community participating. An increase in the number of vaccines given to children and the increased percentage of children receiving vaccines has resulted in a dramatic decrease in the number of vaccine-preventable diseases. In the United States, most young parents as of 2004 had never seen many of diseases that vaccines prevent. Even people who do not develop immunity through vaccination are safer because their friends, neighbors, children, and coworkers are immunized.

Factors influencing recommendations for childhood vaccination include age-specific risks of disease and complications, the ability of a given age group to respond to the vaccine, and the potential interference with the immune response to transferred maternal antibody. There are vaccines for the youngest age group at risk for developing the disease and known to develop a satisfactory antibody response to the vaccination.

Like most medical procedures, vaccination has risks as well as great benefits. When children receive a vaccine, parents should be told about both. Questions or concerns should be discussed with a doctor or other healthcare provider. The Centers for Disease Control and Prevention, located in Atlanta, Georgia, is also a good resource for information.

Vaccines may cause problems for children with certain allergies. Children who are allergic to the antibiotics neomycin or polymyxin B should not take rubella vaccine, measles vaccine, mumps vaccine, or the combined measles-mumps-rubella (MMR) vaccine. Children who have had a severe allergic reaction to baker's yeast should not take the hepatitis B vaccine. Patients who are allergic to antibiotics such as gentamicin sulfate, streptomycin sulfate, or other amino glycosides should check with their doctors before the taking influenza vaccine, as some influenza vaccines contain small amounts of these drugs. Also, some vaccines, including those for influenza, measles, and mumps, are grown in the laboratory in fluids of chick embryos, and should not be given to children who are allergic to eggs. In general, parents of children who have had an unusual reaction to a vaccine in the past should report the reaction to the doctor before taking the same vaccine again. Doctors need to know about allergies to foods, medicines, preservatives, or other substances.

Children with other medical conditions should be given vaccines with caution. Influenza vaccine may reactivate Guillain-Barre syndrome (GBS) in patients who have had it before. This vaccine also may worsen illnesses that involve the lungs, such as bronchitis or pneumonia. Vaccines that cause fever as a side effect may trigger seizures in people who have a history of seizures caused by fever.

Certain vaccines are not recommended during pregnancy. However, women who are at risk of getting specific disease such as polio may receive the vaccine to prevent medical problems in their babies. Vaccinating a pregnant woman with tetanus toxoid can prevent tetanus in the baby at birth.

Women should avoid becoming pregnant for three months after taking rubella vaccine, measles vaccine, mumps vaccine, or the combined measles-mumps-rubella (MMR) as these vaccines may cause problems in the unborn baby.

Women who are breastfeeding should check with their doctors before taking any vaccine.

Side Effects

Most side effects from vaccines are minor and easily treated. The most common are pain, redness, and swelling at the injection site. Some children may also develop a fever or a rash. Rarely, vaccines may cause severe allergic reactions, swelling of the brain, or seizures. Unusual reaction after receiving a vaccine should be reported to the doctor right away.

Interactions

Vaccines may interact with other medicines and medical treatments. When this happens, the effects of the vaccine or the other medicine may change or the risk of side effects may be greater. Radiation therapy and cancer drugs may reduce the effectiveness of many vaccines or may increase the chance of side effects. Parents should let the doctor know of all medicines taken by the child and learn whether the possible interactions could interfere with the therapeutic effects of the vaccine or the other medicines.

Parental Concerns

All vaccines used for routine child vaccinations in the United States may be given simultaneously. There is no evidence that simultaneous administration of vaccines either reduces vaccine effectiveness or increases the risk of adverse events. The only vaccines which should not be given at the same time are cholera and yellow fever vaccines.

Some vaccines are mixed in one solution, such as measles-mumps-rubella (MMR) and diphtheria-tetanus-pertussis (DTP) combination. A survey of the literature as of 2004 indicated no evidence supporting the idea that multiple vaccines in any way overwhelm or weaken the immune system. Most young infants have strong immune systems that are capable of responding to all the recommended vaccines. The protection from bacterial and viral infections provided by vaccines preserves the infant's immune systems to fight off other infections.

Most doctors follow the recommended vaccination schedule, with some flexibility. For example, vaccinations that are scheduled for age two months may be given anytime between six to 10 weeks. Slight departures from the schedule will not stop the child from developing immunity, as long as the child gets all the vaccinations close the right times.

Immunizations are not given when a child has signs of an acute illness. An interrupted primary series of immunizations need not started again but may simply continue after the child recovers. The child's doctor is the best person to decide when each vaccination should be given.

The eventual goal in child care is to reduce stress. Parents should try to increase the child's feeling of security and well-being by close involvement with the immunization process. Providing explanations of the immunization plan, special tests, and procedures suitable to the child's age is helpful. Infants and toddlers are not likely to understand verbal explanations, but they have a strong parental attachment and need affection to ease fears. Small children also have an urgent need for their mothers to defend them during medical treatments. Older children may even protest or despair in getting an injection but are usually accepting of reasonable explanations.

The health-care professional reviews the immunization record and the health status of the child at each visit. If necessary the nurse or doctor helps the parent correctly position the child and exposure of the injection site. Parents should hold a small child on their laps securely for the injection; older children may be put on the examination table in the doctor's office. After the injection, parents can give the child immediate comfort to control crying and then leave the treatment room.

Resources

Books

Institute of Medicine Staff, et al. Immunization Safety Review: Multiple Immunizations and Immune Dysfunction. Washington, DC: National Academy Press, 2002.

Kassianos, George C., et al. Immunization: Childhood and Travel Health. Oxford, UK: Blackwell Publishing Inc., 2001.

Parents Guide to Childhood Immunization. Washington, DC: U.S. Government Publishing Office, 2001.

Studor, Hans-Peter, et al. Vaccination: A Guide for Making Personal Choices. Edinburgh, Scotland: Floris Books, 2004.

Web Sites

Centers for Disease Control National Immunization Program. Available online at www.cdc.gov/nip (accessed December 3, 2004).

"Vaccination Recommendations for Infants and Children." CDC Travelers' Health: Health Information for International Travel, 2003–2004. Available online at www.cdc.gov/travel/child-vax.htm (accessed December 3, 2004).

[Article by: Aliene S. Linwood, RN, DPA, FACHE]

Vaccination, a term first used by Jenner (1798) for inoculating cowpox matter (vacca = cow) to produce immunity from the far more virulent smallpox, has since come to mean the creation of immunity from infectious diseases in general. The 1840 Vaccination Act prohibited inoculation and permitted vaccination of the poor at ratepayers' expense; the 1853 extension made the practice compulsory, though it was not universally enforced. With compulsory notification of infectious diseases and better trained public health officers, vaccination rapidly reduced the prevalence and mortality of smallpox. Subsequent vaccines against diphtheria, polio, measles, whooping cough, and rubella have largely controlled these diseases.

The administration of a vaccine to confer immunity against a specific disease. Originally, the term was confined to the use of vaccinia (cowpox virus), but it is now used synonymously with inoculation.

United States President George W. Bush authorized a program on December 13, 2002, which by its conclusion, will see approximately 500,000 military personnel vaccinated against smallpox, along with an equal number of key healthcare providers in the United States. In the event of a biological attack that would expose Americans to smallpox, the affected citizens could then be quickly vaccinated by the protected healthcare workers. Additionally, the vaccine will be offered to up to ten million police, firefighters, and other first responders to emergencies. Smallpox vaccination within three days of exposure will usually prevent development of the disease, or dramatically reduce its virulence. Plentiful stocks are on hand in the U.S. to respond to a large smallpox outbreak, and vaccine in quantities necessary for inoculation of the entire population of the United States are in production. By mid-2004, health officials plan to have smallpox vaccinations available on a voluntary basis for all Americans.

An anthrax vaccine is also available and is only routinely given to laboratory workers who are involved with B. anthracis study or cultures. Vaccination for anthrax prevention involves a series of six injections over an 18-month period. Over 500,000 military personnel received the vaccine as a precaution in 2002, but for the general population, including medical providers and first responders, the vaccine is not currently recommended as other options such as antibiotic treatment offer protection to individuals exposed to anthrax-causing bacteria.

Diseases like anthrax and smallpox are among those microbial diseases that could be exploited as biological weapons. Indeed, anthrax was sent through the postal system to targets in the United States in the aftermath of the September 11, 2001 terrorist attacks in the U.S. Anthrax is a disease caused by the bacterium Bacillus anthracis, which can infect the skin, digestive tract, or lungs. Lung infection is often fatal. Smallpox is an extremely contagious disease that is caused by the variola virus.

Vaccination refers to the procedure in which the presence of a component of a microorganism such as a protein (the antigen) stimulates the defense mechanism of the host, which is known as the immune system, to form an antibody. Each antibody is formed in specific response to a particular antigen. The antibodies act to protect the host from future exposure to the antigen (immunity). Depending on the disease and the nature of the vaccine, the immunity can last from a year or two (i.e., influenza) to a lifetime.

Vaccination is protective against infection without the need of suffering through a bout of a disease. In this artificial process an individual receives the antibody-stimulating compound either by injection or orally. Some vaccines like that for smallpox do contain live microorganisms, which can cause some discomfort and, in rare cases, more serious complications. Nonetheless, for most people, vaccination is a prudent step to avoid the threat of a disease. As of early 2003, only one healthcare worker having received the recent smallpox vaccine reported a related complication, a non-life threatening vaccina rash. Less than a dozen instances of complication (none considered serious) have been reported among military personnel receiving the vaccine.

The technique of vaccination has been practiced since at least the early decades of the eighteenth century. Then, a common practice in Istanbul, Turkey was to retrieve material from the surface sores of a smallpox sufferer and rub the material into a cut on another person. The recipient was often spared the ravages of smallpox. This practice was noted by Lady Mary Wortley Montague, the wife of the British Ambassador Extraordinary to the Turkish court. Upon her return to England, she used her social standing to promote the benefits of this crude method of smallpox inoculation. Among those who were convinced was the Royal Family. Indeed, it became fashionable to receive an inoculation, partly perhaps it carried social cache. The technique was refined by Edward Jenner into a vaccine for cowpox in 1796.

Since Jenner's time, vaccines for a variety of bacterial and viral maladies have been developed. The material used for vaccination is one of four types. Some vaccines consist of living but weakened viruses. Such an attenuated vaccine does not cause an infection but does elicit an immune response. An example is the measles, mumps, and rubella (MMR) vaccine. The second type of vaccine can involve killed viruses or bacteria. The virus or bacteria need to be killed in a way that does not perturb their surfaces. This care is necessary to preserve the three-dimensional structure of surface molecules that stimulate the immune response. Agents such as alum can be used to enhance the immune response to the killed target, perhaps by exposing the antigen to the immune system for a longer time. A third type of vaccination involves a toxoid, which is an inactivated form of a toxin produced by the target bacterium. Examples of toxoid vaccines are the diphtheria and tetanus vaccines. Lastly, a biosynthetic vaccine can utilize a synthetic compound pieced together from portions of two antigens. The Hib vaccine is a biosynthetic vaccine.

Vaccinations against some diseases occurs early in life. For example, during an infant's first two years of life, a series of vaccinations is recommended to develop protection against hepatitis B, polio, measles, mumps, ru-bella (also called German measles), pertussis (also called whooping cough), diptheriae, tetanus (lockjaw), Haemophilus influenzae type b, pneumococcal infections, and chickenpox. Multiple injections of the vaccine can be required to ensure that the immunity that develops is long lasting. For example, vaccination against diphtheria, tetanus, and pertussis is typically administered at 2 months of age, 4 months, 6 months, 15 to 18 months, and finally at 4 to 6 years of age.

A series of vaccinations such as the above triggers a greater production of antibody by the immune system.

The immune cells that respond to the presence of an antigen in a vaccine are called lymphocytes. Prior to vaccination there are a multitude of lymphocytes, each of which recognizes a single specific protein or a portion of the protein. The presence of a specific antigen stimulates that lymphocyte that recognizes the antigenic target. That lymphocyte will then divide repeatedly and the daughter cells will produce antibody. Eventually, there are many daughter lymphocytes and a lot of antibody circulating in the body.

If the antigen does not persist in the body, the production of antibodies will stop. But the lymphocytes that have been produced still retain the memory of the target protein. When the target is presented again to the lymphocytes, as happens in the second vaccination in a series, the many lymphocytes are stimulated to divide into daughter cells, which in turn form antibodies. This is because the immune cells that responded to the antigen upon the first exposure "remember" the antigen, and so can produce even more antibody when presented with the antigen a second or third time. In immunological terms the immune cells are said to be "primed." This form of antigenic memory can last for a lifetime for diseases such as diphtheria and pertussis. For other diseases such as tetanus adults should be vaccinated every ten years (a "booster shot") in order to keep their bodies primed to fight the tetanus microorganism.

Many vaccinations are given via injection. However, solutions that can be drunk are also used. The classic example is the oral vaccine to polio devised by Albert Sabin. Oral vaccination is often limited by the passage of the vaccine through the highly acidic stomach. In the future is hoped that the bundling of the vaccine in a protective casing will prevent the damage caused in the stomach. Experiments using bags made out of lipid molecules (liposomes) has demonstrated both protection of the vaccine and the ability to tailor the liposome release of the vaccine.

While the benefits of vaccination are obvious, this protection against disease does not come without a risk. For a variety of vaccines, side effects are possible. For some vaccines, the side effects are minor. A person may, for example, develop a slight ache and redness at the site of injection. In some very rare cases, however, more severe reactions can occur, such as convulsions and high fever. The smallpox vaccine carries the risk of encephalitis (swelling of cells of the brain and spinal cord) in approximately three to 12 people per million people vaccinated.

Further Reading

Books

Joellenbeck, Lois M., Lee L. Zwanziger, Jane S. Durch, and Brian L. Strom. The Anthrax Vaccine: Is It Safe? Does It Work? Washington: Joseph Henry Press, 2002.

Murphy, Christine. The Vaccine Dilemma. New York: Lantern Books, 2000.

Neustaedter, Randall. The Vaccine Guide: Risks and Benefits for Children and Adults. Berkeley: North Atlantic Books, 2002.

Electronic

Centers for Disease Control and Prevention. "Vaccine Fact Sheets." National Vaccine Program Office. November 23, 2002. <http://www.cdc.gov/od/nvpo/fs_toc.htm>(6 January 2003).

Inoculation with a vaccine to produce immunity to a particular infectious disease.

The introduction of vaccine into the body to produce immunity to a specific disease. The vaccine may be administered by subcutaneous or intradermal injection, by infusion into the mammary gland, by mouth or by inhalation of an aerosol. The term vaccination comes from the Latin vacca, cow, and was coined when the first inoculations were given with organisms that caused the mild disease cowpox to produce immunity against smallpox. Today the word has the same meaning as immunization.

• v. failure — following administration of a vaccine, the animal develops the disease. The cause is often related to faulty inactivation of the vaccine due to improper handling or inappropriate administration, or the animal was incubating the disease at the time of vaccination.
• v. schedules — specified ages and intervals for administration of vaccines to ensure the best immunological response.
• simultaneous serum-virus v. — simultaneous administration of live virus and hyperimmune serum. Used at one time in the control of several diseases, including canine distemper and classical swine fever (hog cholera).

Vaccination in a dream can relate to sickness in one's waking life. Perhaps feeling the need to protect oneself from a particular situation or the influence of others. Could also be a sexual symbol. (See also Illness; Needle; Syringe).

Child receiving an oral polio vaccine.

Vaccination is the administration of antigenic material (the vaccine) to produce immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by a pathogen. Vaccination is generally considered to be the most effective and cost-effective method of preventing infectious diseases. The material administrated can either be live but weakened forms of pathogens (bacteria or viruses), killed or inactivated forms of these pathogens, or purified material such as proteins. Smallpox was the first disease people tried to prevent by purposely inoculating themselves with other types of infections; smallpox inoculation was started in China or India before 200 BC.^[1] In 1718, Lady Mary Wortley Montagu reported that the Turks had a habit of deliberately inoculating themselves with fluid taken from mild cases of smallpox, and that she had inoculated her own children.^[2] Before 1796 when British physician Edward Jenner tested the possibility of using the cowpox vaccine as an immunisation for smallpox in humans for the first time, at least six people had done the same several years earlier: a person whose identity is unknown, England, (about 1771); a Mrs. Sevel, Germany (about 1772); a Mr. Jensen, Germany (about 1770); Benjamin Jesty, England, in 1774; a Mrs. Rendall, England (about 1782); and Peter Plett, Germany, in 1791.^[3]

The word vaccination was first used by Edward Jenner in 1796. Louis Pasteur furthered the concept through his pioneering work in microbiology. Vaccination (Latin: vacca—cow) is so named because the first vaccine was derived from a virus affecting cows—the relatively benign cowpox virus—which provides a degree of immunity to smallpox, a contagious and deadly disease. In common speech, 'vaccination' and 'immunization' generally have the same colloquial meaning. This distinguishes it from inoculation which uses unweakened live pathogens, although in common usage either is used to refer to an immunization. The word "vaccination" was originally used specifically to describe the injection of smallpox vaccine.^[1][3]

Vaccination efforts have been met with some controversy since their inception, on ethical, political, medical safety, religious, and other grounds. In rare cases, vaccinations can injure people and they may receive compensation for those injuries. Early success and compulsion brought widespread acceptance, and mass vaccination campaigns were undertaken which are credited with greatly reducing the incidence of many diseases in numerous geographic regions.

Contents 1 Triggering immune sensitization 2 Types of vaccinations 3 History 4 Policies and enforcement 5 Adjuvants and preservatives 6 Methods of administration 7 Research 8 See also 9 References 10 External links

Triggering immune sensitization

In the generic sense, the process of artificial induction of immunity, in an effort to protect against infectious disease, works by 'priming' the immune system with an 'immunogen'. Stimulating immune response, via use of an infectious agent, is known as immunization. Vaccinations involve the administration of one or more immunogens, which can be administered in several forms.

Some modern vaccines are administered after the patient already has contracted a disease, as in the cases of experimental AIDS, cancer and Alzheimer's disease vaccines. Vaccinia given after exposure to smallpox, within the first four days, is reported to attenuate the disease considerably, and vaccination within the first week is known to be beneficial to a degree. The first rabies immunization was given by Louis Pasteur to a child bitten by a rabid dog, subsequently post-exposure immunization to rabies has generally been followed by survival. The essential empiricism behind such immunizations is that the vaccine triggers an immune response more rapidly than the natural infection itself.

Most vaccines are given by hypodermic injection as they are not absorbed reliably through the intestines. Live attenuated polio, some typhoid and some cholera vaccines are given orally in order to produce immunity based in the bowel.

Types of vaccinations

All vaccinations work by presenting a foreign antigen to the immune system in order to evoke an immune response, but there are several ways to do this. The four main types that are currently in clinical use are as follows:

1. An inactivated vaccine consists of virus particles which are grown in culture and then killed using a method such as heat or formaldehyde. The virus particles are destroyed and cannot replicate, but the virus capsid proteins are intact enough to be recognized and remembered by the immune system and evoke a response. When manufactured correctly, the vaccine is not infectious, but improper inactivation can result in intact and infectious particles. Since the properly produced vaccine does not reproduce, booster shots are required periodically to reinforce the immune response.
2. In an attenuated vaccine, live virus particles with very low virulence are administered. They will reproduce, but very slowly. Since they do reproduce and continue to present antigen beyond the initial vaccination, boosters are required less often. These vaccines are produced by passaging virus in cell cultures, in animals, or at suboptimal temperatures, allowing selection of less virulent strains, or by mutagenesis or targeted deletions in genes required for virulence. There is a small risk of reversion to virulence, this risk is smaller in vaccines with deletions. Attenuated vaccines also cannot be used by immunocompromised individuals.
3. Virus-like particle vaccines consist of viral protein(s) derived from the structural proteins of a virus. These proteins can self-assemble into particles that resemble the virus from which they were derived but lack viral nucleic acid, meaning that they are not infectious. Because of their highly repetitive, multivalent structure, virus-like particles are typically more immunogenic than subunit vaccines (described below). The human papillomavirus and Hepatitis B virus vaccines are two virus-like particle-based vaccines currently in clinical use.
4. A subunit vaccine presents an antigen to the immune system without introducing viral particles, whole or otherwise. One method of production involves isolation of a specific protein from a virus or bacteria (such as a bacterial toxin) and administering this by itself. A weakness of this technique is that isolated proteins may have a different three-dimensional structure than the protein in its normal context, and will induce antibodies that may not recognize the infectious organism. In addition, subunit vaccines often elicit weaker antibody responses than the other classes of vaccines.

A number of other vaccine strategies are under experimental investigation. These include DNA vaccination and recombinant viral vectors.

History

Jenner's handwritten draft of the first vaccination.

Early forms of vaccination were developed in ancient China as early as 200 B.C.^[1] Scholar Ole Lund comments: "The earliest documented examples of vaccination are from India and China in the 17th century, where vaccination with powdered scabs from people infected with smallpox was used to protect against the disease. Smallpox used to be a common disease throughout the world and 20% to 30% of infected persons died from the disease. Smallpox was responsible for 8 to 20% of all deaths in several European countries in the 18th century. The tradition of vaccination may have originated in India in AD 1000."^[4] The mention of vaccination in the Sact'eya Grantham, an Ayurvedic text, was noted by the French scholar Henri Marie Husson in the journal Dictionaire des sciences me`dicales.^[5] Almroth Wright, the professor of pathology at Netley, further helped shape the future of vaccination by conducting limited experiments on the professional staff at Netly, including himself. The outcome of these experiments resulted in further development of vaccination in Europe.^[6] The Anatolian Ottoman Turks knew about methods of vaccination about a hundred years before Edward Jenner to whom the discovery is attributed. They called vaccination Ashi or engrafting, which they used to apply to their children with cowpox taken from the breast of cattle. This kind of vaccination and other forms of variolation were introduced into England by Lady Montagu, a famous English letter-writer and wife of the English ambassador at Istanbul between 1716 and 1718, who'd almost died from smallpox as a young adult and was physically scarred from it. She came across the Turkish methods of vaccination, consenting to have her son inoculated by the Embassy surgeon Charles Maitland in the Turkish way. Lady Montagu wrote to her sister and friends in England describing the process in details. On her return to England she continued to propagate the Turkish tradition of vaccination and had many of her relatives inoculated. The breakthrough came when a scientific description of the vaccination operation was submitted to the Royal Society in 1724 by Dr Emmanual Timoni, who had been the Montagu’s family physician in Istanbul. Inoculation was adopted both in England and in France nearly half a century before Jenner's famous smallpox vaccine of 1796.^[7]

Since then vaccination campaigns have spread throughout the globe, sometimes prescribed by law or regulations (See Vaccination Acts). Vaccines are now used to fight a wide variety of disease threats besides smallpox. Louis Pasteur further developed the technique during the 19th century, extending its use to protecting against bacterial anthrax and viral rabies. The method Pasteur used entailed treating the infectious agents for those diseases so they lost the ability to cause serious disease. Pasteur adopted the name vaccine as a generic term in honor of Jenner's discovery, which Pasteur's work built upon.

A doctor performing a typhoid vaccination, 1943.

Prior to vaccination with cowpox, the only known protection against smallpox was inoculation or variolation (Variola - the Smallpox viruses) where a small amount of live smallpox virus was administered to the patient; this carried the serious risk that the patient would be killed or seriously ill. The death rate from variolation was reported to be around a tenth of that from natural infection with Variola, and the immunity provided was considered quite reliable. Factors contributing to the efficacy of variolation probably include the choices of Variola Minor strains used, the relatively low number of cells infected in the first phase of multiplication following initial exposure, and the exposure route used, via the skin or nasal lining rather than inhalation of droplets into the lungs.

Consistency would suggest the activity should have predated Jenner's description of an effective vaccination system, and there is some history relating to opposition to the older and more hazardous procedure of variolation^{[citation needed]}.

In modern times, the first vaccine-preventable disease targeted for eradication was smallpox. The World Health Organization (WHO) coordinated the global effort to eradicate this disease. The last naturally occurring case of smallpox occurred in Somalia in 1977.

In 1988, the governing body of WHO targeted polio for eradication by the year 2000. Although the target was missed, eradication is very close. The next eradication target would most likely be measles, which has declined since the introduction of measles vaccination in 1963.

In 2000, the Global Alliance for Vaccines and Immunization was established to strengthen routine vaccinations and introduce new and under-used vaccines in countries with a per capita GDP of under US$1000. GAVI is now entering its second phase of funding, which extends through 2014.

Policies and enforcement

Poster for vaccination against smallpox.

Main article: Vaccination policy

Further information: Vaccine controversy and Vaccine injury

In an attempt to eliminate the risk of outbreaks of some diseases, at various times several governments and other institutions have instituted policies requiring vaccination for all people. For example, an 1853 law required universal vaccination against smallpox in England and Wales, with fines levied on people who did not comply. Common contemporary U.S. vaccination policies require that children receive common vaccinations before entering school. Most other countries also have some compulsory vaccinations.

Beginning with early vaccination in the nineteenth century, these policies led to resistance from a variety of groups, collectively called anti-vaccinationists, who objected on ethical, political, medical safety, religious, and other grounds. Common objections are that compulsory vaccination represents excessive government intervention in personal matters, or that the proposed vaccinations are not sufficiently safe.^[8] Many modern vaccination policies allow exemptions for people who have compromised immune systems, allergies to the components used in vaccinations or strongly-held objections.^[9]

Allegations of vaccine injuries in recent decades have appeared in litigation in the U.S. Some families have won substantial awards from sympathetic juries, even though most public health officials believed that the claims of injuries were unfounded.^[10] In response, several vaccine makers stopped production, threatening public health, and laws were passed to shield makers from liabilities stemming from vaccine injury claims.^[10]

Adjuvants and preservatives

Vaccines typically contain one or more adjuvants, used to boost the immune response. Tetanus toxoid, for instance, is usually adsorbed onto alum. This presents the antigen in such a way as to produce a greater action than the simple aqueous tetanus toxoid. People who get an excessive reaction to adsorbed tetanus toxoid may be given the simple vaccine when time for a booster occurs.

In the preparation for the 1990 Gulf campaign, Pertussis vaccine (not acellular) was used as an adjuvant for Anthrax vaccine. This produces a more rapid immune response than giving only the Anthrax, which is of some benefit if exposure might be imminent.

They may also contain preservatives, which are used to prevent contamination with bacteria or fungi. Until recent years, the preservative thiomersal was used in many vaccines that did not contain live virus. As of 2005^[update], the only childhood vaccine in the U.S. that contains thiomersal in greater than trace amounts is the influenza vaccine [1], which is currently recommended only for children with certain risk factors.^[11] The UK is considering Influenza immunisation in children perhaps as soon as in 2006-7. Single-dose Influenza vaccines supplied in the UK do not list Thiomersal (its UK name) in the ingredients. Preservatives may be used at various stages of production of vaccines, and the most sophisticated methods of measurement might detect traces of them in the finished product, as they may in the environment and population as a whole [2].

Methods of administration

A vaccine administration may be oral, by injection (intramuscular, intradermal, subcutaneous), by puncture, transdermal or intranasal.^[12]

Research

Some major contemporary research in vaccination focuses on development of vaccinations for diseases including HIV and malaria.

Vaccine is an international peer-reviewed journal for vaccination researchers, indexed in Medline pISSN: 0264-410X.

See also

• Influenza vaccine
• H5N1 flu vaccine clinical trials
• Vaccine trial
• Vaccination of dogs
• Feline vaccination
• Immunization during pregnancy

References

1. ^ ^{a b c} Lombard M, Pastoret PP, Moulin AM (2007). "A brief history of vaccines and vaccination". Rev. - Off. Int. Epizoot. 26 (1): 29–48. PMID 17633292. 
2. ^ Behbehani AM (1983). "The smallpox story: life and death of an old disease". Microbiol. Rev. 47 (4): 455–509. PMID 6319980. http://mmbr.asm.org/cgi/pmidlookup?view=long&pmid=6319980. 
3. ^ ^{a b} Plett PC (2006). "[Peter Plett and other discoverers of cowpox vaccination before Edward Jenner]" (in German). Sudhoffs Arch 90 (2): 219–32. PMID 17338405. http://lib.bioinfo.pl/meid:4459. Retrieved 2008-03-12. 
4. ^ Lund, Ole; Nielsen, Morten Strunge and Lundegaard, Claus (2005). Immunological Bioinformatics. MIT Press. ISBN 0262122804
5. ^ Chaumeton, F.P.; F.V. Me`rat de Vaumartoise. Dictionaire des sciences me`dicales. Paris: C.L.F. Panckoucke, 1812-1822, lvi (1821).
6. ^ Curtin, Phillip (1998). "Disease and Empire: The Health of European Troops in the Conquest of Africa". Cambridge University Press. ISBN 0521598354
7. ^ Anthony Henricy (ed.) (1796). Lady Mary Wortley Montagu,Letters of the Right Honourable Lady Mary Wortley Montagu:Written During her Travels in Europe,Asia and Africa. 1. pp. 167–169. 
8. ^ Wolfe R, Sharp L (2002). "Anti-vaccinationists past and present". BMJ 325 (7361): 430–2. doi:10.1136/bmj.325.7361.430. PMID 12193361. http://bmj.bmjjournals.com/cgi/content/full/325/7361/430. 
9. ^ Salmon DA, Teret SP, MacIntyre CR, Salisbury D, Burgess MA, Halsey NA (2006). "Compulsory vaccination and conscientious or philosophical exemptions: past, present, and future". Lancet 367 (9508): 436–42. doi:10.1016/S0140-6736(06)68144-0. PMID 16458770. 
10. ^ ^{a b} Sugarman SD (2007). "Cases in vaccine court—legal battles over vaccines and autism". N Engl J Med 357 (13): 1275–7. doi:10.1056/NEJMp078168. PMID 17898095. http://content.nejm.org/cgi/content/full/357/13/1275. 
11. ^ Melinda Wharton. National Vaccine Advisory committee U.S.A. national vaccine plan
12. ^ Plotkin, Stanley A. (2006). Mass Vaccination: Global Aspects - Progress and Obstacles (Current Topics in Microbiology & Immunology). Springer-Verlag Berlin and Heidelberg GmbH & Co. K. ISBN 978-3540293828. 

External links

Wikimedia Commons has media related to: Vaccinations

• Vaccine Research Center: Information regarding preventative vaccine research studies
• The Vaccine Page links to resources in many countries.
• Immunisation Immunisation schedule for children in the UK. Published by the UK Department of Health.
• CDC.gov - 'National Immunization Program: leading the way to healthy lives', US Centers for Disease Control (CDC information on vaccinations)
• CDC.gov - 'Mercury and Vaccines (Thimerosal)', US Centers for Disease Control
• Immunize.org - Immunization Action Coalition' (nonprofit working to increase immunization rates)
• WHO.int - 'Immunizations, vaccines and biologicals: Towards a World free of Vaccine Preventable Diseases', World Health Organization (WHO's global vaccination campaign website)
• Health-EU Portal Vaccinations in the EU

v • d • e Artificial induction of immunity / Immunization: Vaccines, Vaccination, and Inoculation (J07) Development Adjuvants · Mathematical modelling · Timeline · Trials Classes: Inactivated vaccine · Live vector vaccine (Attenuated vaccine, Heterologous vaccine) · Toxoid · Subunit/component/Virus-like particle · Conjugate vaccine · DNA vaccination Administration Global: GAVI Alliance · Policy · Schedule · Vaccine injury USA: ACIP · VAERS · VSD · Vaccine court Vaccines Bacterial Anthrax · Brucellosis · Cholera# · Diphtheria# · Hib# · Meningococcus# (NmVac4-A/C/Y/W-135, NmVac4-A/C/Y/W-135 - DT, MeNZB) · Pertussis# · Plague · Pneumococcal# (PPSV, PCV) · Tetanus# · Tuberculosis (BCG)# · Typhoid# (Ty21a, ViCPS) · Typhus combination: DTwP/DTaP Viral Adenovirus · Tick-borne encephalitis · Japanese encephalitis# · Flu# (Pandemrix, LAIV, H1N1) · HAV# · HBV# · HPV (Gardasil, Cervarix) · Measles# · Mumps# (Mumpsvax) · Polio# (Salk, Sabin) · Rabies# · Rotavirus# · Rubella# · Smallpox (Dryvax) · Varicella (chicken pox)# · Yellow fever# combination: MMR · MMRV research: Cytomegalovirus · Epstein-Barr · HIV · Hepatitis C Protozoan Malaria · Trypanosomiasis Helminthiasis Schistosomiasis · Hookworm Other TA-CD · NicVAX · Cancer vaccines (ALVAC-CEA vaccine) Controversy General · MMR · NCVIA · Pox party · Simpsonwood · Thiomersal See also List of vaccine topics · Epidemiology · Eradication of infectious diseases #WHO-EM. ‡Withdrawn from market. CLINICAL TRIALS: †Phase III. §Never to phase III

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)