Vaccinations: An Overview Image

The purpose of vaccines is to prevent people from getting certain diseases. Vaccines work by exposing the body to weakened or dead elements of specific bacteria cells or viruses. These elements induce an immune response in the body, introducing the body to the bacteria or virus so it can recognize and protect against it in the future.

How Vaccinations Work

To understand how vaccinations work, you first need to understand how the human immune system works. When bacteria, viruses or other germs invade the body, the immune system produces antibodies to destroy them. After the germs are gone, certain antibodies remain in the body. If pathogens of the same type attempt to enter the body at a later time, the antibodies recognize and effectively destroy the pathogens so you don’t get sick.

Vaccines usually contain a weakened or dead form of the bacteria or virus itself. Administering the weakened or dead cells into the body induces a specific immune response that creates antibodies. The effectiveness of vaccinations is high, but they’re not 100 percent effective. In addition, some vaccinations require booster shots at regular intervals of additional vaccine doses.

Vaccine Schedule

Every year, the Advisory Committee on Immunization Practices (ACIP) publishes a recommended vaccine schedule for children age 18 and younger along with a vaccine schedule for adults. You can get this vaccine schedule from your healthcare provider or on the Centers for Disease Control and Prevention (CDC) website.

Risks of Vaccines

Vaccines are medications and, like all medications, they have potential side effects. Most side effects are minor (a sore arm or low-grade fever) and go away within a few days. Each specific vaccine has its own list of potential side effects.

For childhood vaccinations, the National Childhood Vaccine Injury Act requires that healthcare providers give parents a vaccine information statement before vaccinating their child. If you’re getting a vaccine as an adult, ask your healthcare provider for this information. Each vaccine also has its own list of people who should not receive that vaccination. In rare cases, people can develop the disease for which they were vaccinated or have another serious reaction.

The Seasonal Flu Vaccine

Each year, medical scientists formulate a seasonal flu vaccine. They design this vaccine to protect against the top three specific flu viruses they think are likely to be most active in the coming flu season. The seasonal flu vaccine protects you only against the specific flu viruses included in that season’s vaccine. Because this vaccine is based on prediction, it’s not always accurate.

Sometimes a shortage of flu vaccines occurs because the large quantity of vaccines cannot be manufactured in time. In these cases, priority for vaccines usually goes to those over 65, young children, pregnant women and people with immune deficiencies.

Weighing the Risks and Benefits

Although the official medical opinion is that vaccines are safe, controversy does surround vaccinations, with some people claiming they have more potential side effects than officially acknowledged. Weigh the risks and benefits of vaccines for yourself before you or your children get vaccinated. Talk to your doctor for more information.


Centers for Disease Control and Prevention. (2010). Vaccines and immunizations. Retrieved August 25, 2010, from

National Network for Immunization Information. (n.d.). How vaccines work.