because some of them may be harmful to the body
Vaccines are made using the disease-causing virus or bacteria.
Vaccines for the prevention of the specific viral infection can be made with inactive "dead" viruses. They are also made with live, but attenuated (weakened), viruses. See more below about vaccines.
Cholera Vaccine. Flu vaccines formulated for injection use inert/inactive virus particles ("dead"), while flu vaccines for nasal mist are made as a LAIV (live attenuated influenza vaccine), which means they are "alive" but weakened chemically to prevent them from being able to cause illness.
Protists are not commonly used in the development of vaccines. Vaccines are typically made using viruses, bacteria, or parts of these organisms to stimulate the immune system to produce an immune response. Protists are a diverse group of eukaryotic microorganisms, but their use in vaccines is limited.
We need vaccines to protect us from infectious diseases and to trigger the immune system to respond with production of antibodies made for that specific pathogen. See the related questions for more details of how this works.
Alexander Fleming accidentally discovered Penicillin in 1940, when he noticed that bacterial colonies died when they were near a fungus named Penicillium notatum. That marked the beginning of the antibiotics era. Penicillin was made available in 1950.
The immune system is the body's defense system against harmful of disease causing microorganisms. The immune system is made up of the lymphatic system, and white blood cells.
Attenuated simply means "weakened". An attenuated flu vaccine refers to vaccines made with live viruses (so you get a good immune response), but they have been weakened chemically so that they are unable to give you the flu. There are two types of flu vaccines available in the US. What is called inactivated, inactive or "dead" vaccine and what is called "live", weakened/attenuated vaccine. The injectable vaccines (intradermal and intramuscular) are made with "dead" viruses and the nasal spray is made with "live" attenuated viruses.
Yes, the kind given by injection are considered "dead", because they are in an inactive state, they don't make you sick. Other vaccines can be made with live "attenuated" viruses, meaning they are active but only partially, since they have been treated to be too weak to cause disease in people who have otherwise healthy immune systems.
No. An uncooked or undercooked burger contains microorganisms, but the burger itself is made from cattle, which are definitely not microorganisms.
No vaccines are made this way. None.
Being more carefully designed makes less mess-ups possible