Global Impact of Vaccinations  

The most significant contribution to the benefit of mankind occurred in the 20th century: the development of vaccines.  No other advancement, except safe water, has had such an important impact on the population of the world, saving hundreds of thousands of lives.

What is a vaccine and how does it work?  Vaccines are preparations designed to provide protection against certain diseases or infections, like tetanus, measles, polio, hepatitis, and the seasonal flu.  They are created by using small amounts of killed or weakened microorganisms (bacteria or virus) that cause a specific disease.  The resulting vaccine stimulates the immune system to react as if a real infection was present in the body.  Once the immune system is stimulated, it recognizes and "remembers" the organism and then fights the infection if the organism enters the body at a later time.  Due to the widespread use of these vaccines, the world has seen a dramatic decline of many infectious diseases, but they still circulate either in the U.S. or in other parts of the world.

Why are vaccines important? Babies are born with immunity that protects them from certain diseases due to antibodies that are passed from the mother during pregnancy.  This immunity is only temporary, however, so vaccines are started once the babies' immune system is developed enough to respond to the vaccines.

Some people feel that they do not have to vaccinate their children because most other people in the community are immunized.  They are relying on what's known as "herd immunity".  This is only effective if all members of the population are vaccinated and the individual remains within the herd.  Once the individual goes beyond the herd, they are susceptible to any disease they have not had, including those that could have been prevented through vaccines.  This is often seen when people travel to areas where vaccines are not given routinely.

The CDC has designed a schedule for the vaccines it recommends, giving the times the vaccines should be started.  Some vaccines require more than one dose to be effective and the schedule includes the intervals between shots in a specific series.  To be effective, all doses of a vaccine series should be given.  If your child is behind on immunizations, there is a "catch-up" schedule your doctor can use.  However, immunizations do not have to be restarted if the schedule between doses is interrupted.

How safe are vaccines?  Vaccines are among the safest and most reliable drugs available.  Some parents may hesitate to have their children vaccinated because they worry there will be serious reactions to the vaccine or that the child may get the illness the vaccine is designed to prevent.  But, because the components of vaccines are weakened or killed, and in some cases, only parts of the microorganism are used, they're very unlikely to cause any serious illness.

What are the reactions to vaccination?  After receiving some vaccines, there may be mild reactions, such as soreness where the shot was given or fever, but serious reactions are rare.  However, the risks of reaction related to the use of vaccinations are small compared with the risks associated with the disease the immunizations are designed to prevent.