How Are Vaccines Made and Why Do They Work?
In their book Vaccines: What Every Parent Should Know, Dr. Paul Offit and Dr. Louis Bell take the complex question of how vaccines are made and answer it in a way we can all understand:
Vaccines are made by taking viruses or bacteria and weakening them so that they can’t reproduce (or replicate) themselves very well or so that they can’t replicate at all. Children given vaccines are exposed to enough of the virus or bacteria to develop immunity, but not enough to make them sick. There are four ways that viruses and bacteria are weakened to make vaccines:
Because the immune response from some vaccines may decrease over time, vaccines known as “boosters” are sometimes given to restore the immune response against that particular germ. Protective immunity lasts longer when boosters are given.
Tetanus boosters, for example, are recommended every 10 years starting at age 10 or 11. A study published in May 2002 by the Annals of Internal Medicine revealed that millions of Americans are vulnerable to tetanus and diphtheria infections because their booster shots have not been kept up to date.
On other fronts in the vaccine field, scientists are trying to find new ways of producing vaccines, particularly using biotechnology and genetic engineering. These new methods would make it unnecessary to produce large quantities of the dangerous pathogens to make vaccines.
In addition to natural or “vaccine-induced” immunity to diseases, there is also “passive” immunity. Passive immunity occurs when someone is injected directly with large quantities of antibodies that are ready to immediately fight a specific virus or bacteria.
These antibodies go to work immediately against any antigen or pathogen. There is no waiting period, as is needed by some vaccines, before sufficient antibodies are produced. However, protection from these antibody injections is temporary. Once the antibodies are cleared from the body, no new antibodies are made.
Doctors use this approach to treat people who have been exposed to hepatitis B, hepatitis A and rabies. Babies born to mothers with hepatitis B are immediately treated with hepatitis B antibodies (called HBIG or hepatitis B immune globulin) and simultaneously immunized against hepatitis B to prevent any infection that might have occurred during the birth process.
Important disclaimer: The information on pkids.org is for educational purposes only and should not be considered to be medical advice. It is not meant to replace the advice of the physician who cares for your child. All medical advice and information should be considered to be incomplete without a physical exam, which is not possible without a visit to your doctor.
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