Immunizations work by helping the body prepare antibodies to fight a disease. This is done by injecting the body with a small amount of either a live or dead virus, which will trigger an immune response from the body. This immune response will occur not only with a vaccination, but also with future exposure to the virus.
Immunizations work by keeping a person safe from contracting a disease “later.” If a person were immunized against a disease, exposure to the disease would immediately set up an immune response, thus protecting the person from actually getting the disease.
Often exposure to and contraction of certain illnesses means one won’t get them again. So exposure and contraction of one virus often leaves a person immune for life, and is the body’s way of making its own immunizations. This does not mean the person won’t get similar viruses with similar symptoms, as with the many rhinoviruses that cause the common cold. However, one may note that in some families, the children will get a rhinovirus the parents don’t get. This tends to be because the parents have already had this particular virus in the past and are now immune to it.
A few viruses do not cause lifelong immunity. Some noted examples are respiratory syncytial virus (RSV). Children at risk may receive immunizations for RSV when they are young, but will not remain immune once immunizations stop. Additionally they can get RSV more than once.
Most immunizations, however, capitalize on the body’s ability to become immune to many types of viruses. Instead of waiting for the person to develop natural immunity by contracting a disease, immunizations expose the body to the disease so the body will learn to defend itself against future exposure.
This is generally thought safer than actually developing immunity by getting a disease. Most viruses or parts of viruses injected cannot cause the disease for which the person becomes immune. There are a couple of exceptions. The chicken pox and measles/mumps/rubella immunizations are taken from live viruses. In rare cases a child may develop one of these viruses after immunizations, but cases tend to be fairly mild.
The oral polio vaccine also carried some risk for contracting polio. This occurred very rarely, and now most often the inactive polio vaccination (IPV), using a dead form of the virus, is used instead. This means a child can’t get polio from the IPV and is likely immunized for life.
Some immunizations do not result in lifelong immunity. Often immunizations must be repeated in early puberty or early adulthood to continue to provide protection from diseases. Many have found that doctor’ recommendations for when to have immunizations has changed over time. It’s advised to consult a doctor about new recommendations for immunizations, particularly for the elderly, and for children as they age.
Some viruses are noted for not being stopped by immunizations. This has been the case with developing an HIV vaccination. The problem with HIV in regards to a vaccination is that HIV attacks the cells that normally trigger an immune response. Since these cells are disabled, they aren’t able to fight off the virus. While some drugs have helped limit HIV severity, no one has yet been able to develop a vaccine, which would make the immune cells respond appropriately.
Further, HIV is a retrovirus, which means it tends to change its shape as the body attempts to fight it. So injecting dead HIV virus into a person might mean the body could fight one form of HIV, but would not be able to recognize it or fight it in other forms.
Learning more about the body’s immune response might result in an HIV vaccination at a later point, but many scientists conclude we are not that close to achieving this. However, for many illnesses, new vaccines may help significantly reduce risk of serious disease. The new vaccination for human papillomavirus is a significant step toward reducing incidence of cervical cancer.