Vaccinations Vaccine Effectiveness

As vaccines gain greater control over diseases, some people question whether or not vaccination laws are still necessary. Some people may even get sick from a disease after vaccination, leading them to question how effective vaccines are. In general, vaccines are extremely effective and are beneficial for individuals, as well as entire populations.

How Well do Vaccines Work?

Most vaccines are about 99 percent effective at protecting a person or animal from a disease, meaning that there is a slight possibility that a vaccinated person could still become sick if exposed to a disease. In many cases, however, this person won’t become as sick as he would have if he hadn’t been vaccinated.

In most cases, vaccines prevent a disease from creating any symptoms or infection, as long as the vaccine is kept up-to-date and any necessary boosters — or follow-up re-vaccinations — are administered.

How Long do Vaccines Work?

People receive vaccinations at different stages in life. During infancy, a child will receive a number of vaccines, most of which in a three- or four-part series. If a child receives all vaccines in these series, she’ll be protected until she enters elementary school, at which point more vaccinations are necessary.

As this child grows up, she’ll need to receive certain vaccinations before she enters college. After that, most vaccines should last the rest of her life. If she’s at particular risk of exposure to a certain disease, a re-vaccination may be necessary to ensure continued protection.

Why are Vaccines Still Necessary?

Because disease outbreaks have generally decreased because of vaccination, some people question the necessity of continued vaccination. Vaccination laws still exist because there is still some risk of getting these diseases. Some diseases that we vaccinate against are very dangerous, or even fatal, so it’s important to consider the safety of the population.

Despite attempted enforcement of vaccination laws, outbreaks sometimes occur, usually in areas or situations where a lot of people live in close quarters, such as in college dorms.

Vaccination laws do all they can to prevent these outbreaks; if these laws didn’t exist, people would have to worry about many more outbreaks. Until diseases have been completely eliminated, vaccination laws will still be necessary.


National Network for Immunization Information. (2007). Parents: Why immunize? Retrieved November 7, 2007, from

U.S. Department of Health and Human Services. (n.d.). The effectiveness of immunizations. Retrieved August 24, 2010, from