Vaccine Safety

by Food and Drug Administration (FDA)

Smallpox and polio have been wiped out in the United States. Cases of measles, mumps, tetanus, whooping cough (pertussis) and other life-threatening illnesses have been reduced by more that 95 percent. Immunization against influenza and pneumonia prevent tens of thousands of deaths annually among elderly persons and those who are chronically ill. As a result, millions of lives have been saved. But don't let the success of vaccines fool you into thinking we no longer need them. Most vaccine-preventable diseases aren't gone.

Steve Berman, M.D., president of the American Academy of Pediatrics and a pediatrician in Denver, says he and his colleagues were devastated to recently see an infant die of whooping cough. "This was a case where the family thought the risks of vaccination outweighed the benefits," Dr. Berman says. The baby was exposed to the disease by two older brothers who hadn't been vaccinated.

Vaccines contain a weakened (attenuated) or killed (inactivated) form of disease-causing bacteria or viruses, or components of these microorganisms, that trigger a response by our body's immune system. For example, vaccines stimulate our bodies to make antibodies — proteins that specifically recognize and target the bacteria and viruses against which the vaccines are designed, and that help eliminate them from the body when we encounter them.

Without vaccine protection, we can easily contract and transmit infectious diseases. It may only take one person, whether it's a family member, a neighbor, or a visitor from another country, to start the spread of a disease. And even immunized individuals can be at risk because no vaccine is ever 100 percent effective for everyone.

Most parents believe in the benefits of vaccination, as evidenced by record high childhood vaccination rates, and more and more adults are getting vaccinated against influenza, pneumococcal disease, and tetanus. But some people who need vaccines don't get them for a variety of reasons, including fear of side effects. Lately, a surge of negative publicity focusing on the risks of vaccines — some of which are unproven or inaccurate — has some wondering whether they do more harm than good. But vaccine experts and the overwhelming majority of health-care providers caution consumers against skipping important vaccinations because of an evening news report or a posting on the Internet.

Sometimes such reports contain unsubstantiated or inaccurate information and don't reflect a balanced view of the risks and benefits of a particular vaccine.

The Food and Drug Administration recommends that consumers arm themselves with the facts about the benefits and risks of vaccines, along with the potential consequences of not vaccinating against certain diseases. According to a Washington state-based organization called Parents of Kids with Infectious Diseases (PKIDS), some parents are shocked to learn that children can die of chickenpox and other vaccine-preventable diseases they hadn't considered a threat.

The FDA's Center for Biologics Evaluation and Research (CBER) regulates vaccines in the United States, and works with several other agencies, including the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH), to study and monitor vaccine safety and effectiveness. New vaccines are licensed only after the FDA thoroughly reviews the results of extensive laboratory studies and clinical trials performed by scientists, physicians, and manufacturers.

For vaccines intended for wide use in healthy populations such as children, clinical testing with careful safety monitoring typically involves thousands of patients before a vaccine is ever licensed. And after a vaccine hits the market, the safety monitoring continues, as does FDA oversight to assure the highest levels of quality control in the vaccine production process.

"We are always monitoring for evidence that might suggest possible problems with vaccines," says Karen Midthun, M.D., director of CBER's office of vaccine research and review. CBER scientists also conduct research to better ensure vaccine safety and to better understand vaccine-related side effects.

A Commitment to Safety

On the surface, it may seem that approaching vaccine safety as a continuous process — always looking into problems and potential problems — implies that vaccines are unsafe. "But it's actually a reflection of our ongoing commitment to safety, and to assuring the prevention of potentially lethal infectious diseases," says Jesse Goodman, M.D., M.P.H., deputy director for medicine at CBER. "It's also the nature of science to seek and implement improvements which make for safer and more effective medical products."

Since 1996, for example, CBER has licensed several acellular pertussis vaccines. Acellular pertussis vaccines use only parts of the disease-causing bacteria and are associated with fewer side effects than the whole cell pertussis vaccines that had been in use. In 1997, the CDC's Advisory Committee on Immunization Practices (ACIP) recommended a switch from using the whole cell pertussis component of the diphtheria, tetanus, pertussis (DTP) vaccine to using acellular pertussis vaccines for all five doses in the childhood schedule.

About the Author

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