A case of chickenpox in childhood normally confers lifelong immunity, regardless of the severity of the case. The cellular immunity that prevents chickenpox can decline with time due to age or from immunosuppression from medications or health conditions.
But I wonder if you might be asking why a blood test for chickenpox antibodies would be negative if you had chickenpox as a child. There are two possible explanations. One is that the original diagnosis of chickenpox was wrong. The other is that you have a false negative test; this can happen sometimes even when you are still immune. In either case, a vaccine for chickenpox may be a good choice. Talk with your healthcare provider about what makes sense give your medical history.
Natural active immunity to chickenpox is developed by being infected with chickenpox disease.
If you want to get your child immunity to chickenpox, the use of chickenpox vaccine is a more controlled approach that has a lower side effect profile than natural chickenpox infection.
If someone has already been infected with chickenpox, they are immune to it. Vaccines are also available. You have immune system in your body. This system recognizes the 'Foreign protein' that has entered in your body in the form of infection. It give rise to cell mediated and humeral immunity against the various infections, once you catch the same. Immunity against the virus infection is usually life long as against the bacterial infections. You get immunity to chickenpox by way of immunization. You can get passive immunity by injecting the chickenpox immunoglobins. Thirdly you can get the immunity by catching the disease by deliberate exposure of the child to chickenpox patient. After the attack of chickenpox you have immunity against the virus.
Most people with a history of chickenpox will be safe if exposed to chickenpox. Certain conditions can make reinfection more likely. "Low immunity" is not a medical diagnosis, and you should contact your health care provider for advice specific to your particular medical condition.
Natural immunity to chickenpox results from previous infection. There is no other way to be naturally immune to chickenpox. Sometimes, the previous infection may be mild enough that the disease was not noticed. You can become artificially immune to chickenpox by getting chickenpox vaccine.
After the infection, you get naturally acquired active immunity to the chickenpox. You have a very low chance of getting chickenpox again because your immune system has made antibodies to fight off.
Having chickenpox confers immunity regardless of the severity or mildness of the illness.
A baby being born immune to chickenpox because the mother is immune is passive immunity. The immunity to chickenpox having been passed to baby from mother in the womb.
A previous occurrence of chickenpox normally provides lifelong immunity. In addition, a person who had chickenpox may get shingles in the future.
If you had chickenpox as a child, there is no special care required if you are pregnant and were exposed to chickenpox.
Yes, as long as you have demonstrated immunity to chickenpox, you can go to work in a medical environment if your son has chickenpox. If you have had chickenpox or shingles diagnosed in the past; if you have had chickenpox vaccine; or if you have had a titer demonstrating immunity, there is no risk. Talk to the infection control department or contact at your facility for details specific to your situation.
Yes, you can give chickenpox vaccine in the same area as other vaccines.