Since the start of widespread vaccinations in the United States, the number of cases of common childhood illnesses like measles and diphtheria has declined dramatically. Immunizations have protected millions of children from potentially deadly diseases and saved thousands of lives.

The reality is that vaccinations still play a crucial role in keeping children healthy. Unfortunately, misinformation about vaccines could make some parents decide not to immunize their children, putting them and others at a greater risk for illness.

Most diseases that can be prevented by vaccines still exist in the world, even in the United States, although they occur rarely. Doctors continue to vaccinate against them because it’s easy to come into contact with illnesses through travel. That includes anyone who may not be properly immunized who’s coming into the United States, as well as Americans traveling overseas.

Vaccines work by preparing your child’s body to fight illness. Each immunization contains either a dead or a weakened germ that cause a particular disease. Your child’s body is fighting the disease by making antibodies that recognize specific parts of that germ. This response means that if your child is ever exposed to the actual disease, the antibodies are already in place and his or her body knows how to combat it, so your child doesn’t get sick. This is called immunity.

One of parents’ most common concerns about vaccines is, “Will the immunization give my child the very disease it’s supposed to prevent?” The answer is – it is impossible to get the disease from any vaccine made with dead bacteria or viruses or just part of the bacteria or virus. Only those immunizations made from weakened live viruses could possibly make a child develop a mild form of the disease, but it’s almost always much less severe than the illness that occurs when a person is infected with the disease-causing virus itself. The risk of disease from vaccination is extremely small.

Childhood immunizations are possibly the best-researched treatment we have. The Food and Drug Administration’s Center for Biologics Evaluation and Research is the government agency responsible for regulating vaccines in the United States. Working in conjunction with the CDC and the National Institutes of Health (NIH), they continuously research and monitor vaccine safety and effectiveness.

New vaccines are licensed only after thorough laboratory studies and clinical trials are conducted, and safety monitoring continues even after a vaccine has been approved. There have been, and will continue to be, improvements that will minimize potential side effects and ensure the best possible safety standards. There is more reliable research to support the safety and effectiveness of vaccines than for any other intervention that we recommend, except for the use of seat belts.

The most common reactions to vaccines are minor and include redness and swelling where the shot was given, fever, or rash. Although in rare cases immunizations can trigger seizures or severe allergic reactions, the risk of these is much lower than that of catching the disease if a child is not immunized. Every year, millions of children are safely vaccinated, and almost all of them experience no significant side effects.

Research is continuing, of course, just as with every other aspect of medicine. We will continue to update our vaccine schedule as recommended, based on the latest reliable studies. But we can assure our patients that we have more confidence in the vaccines we administer, given on the recommended schedule, than in almost anything else we discuss with parents. Please allow us to protect your child with all the recommended routine childhood immunizations.

More information is available at the Children’s Hospital of Philadelphia Vaccine Education Center at