How Vaccines Work
When you get sick, your body’s immune system (the body's ability to fight germs and sickness) creates antibodies that fight off the infection. If you get infected again, your body remembers the germs and responds with the right antibodies, preventing you from getting sick again.
Vaccines work by stimulating the immune system to create antibodies with small amounts of dead or weakened germs that won’t get you sick but will protect you from the disease in the future, sometimes for your entire life.
History of ProtectionBefore vaccines, many diseases that are now rare or completely eliminated were more prevalent in the U.S. than they are today. Smallpox was common across the world, causing illness and death for thousands of years but was completely wiped out in 1980. As recently as the early nineteenth century, hundreds of thousands of children were paralyzed due to polio every year. Thanks to vaccines introduced in the 1950s and 60s, the U.S. has been polio-free for over 30 years. Haemophilus influenzae type B (Hib) once infected 20,000 children per year, but thanks to vaccines it is now extremely rare. The measles is so contagious that 3-4 million people were infected in the U.S. each year, but vaccines have reduced the number of infections by 99%.
Protecting the CommunityWhen you vaccinate, you not only protect yourself and your family but the entire community as well. Vaccines prevent outbreaks by making it harder for diseases to spread, which helps protect people who can’t get vaccinated for various reasons. They make diseases rarer and in some cases eliminate them completely!
The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) constantly monitor vaccine safety, and studies show that the current U.S. supply of vaccines is the safest in history.
Safety Testing & Monitoring ProcessBefore a vaccine is released and recommended, it is rigorously tested for safety and effectiveness. Scientists perform extensive lab testing for years before a vaccine is ever given to a human. The FDA conducts three phases of human trials on volunteers to determine:
- Is the vaccine safe?
- Is it effective?
- What are the side effects?
Vaccines and AutismClinical studies show that there is no link between vaccines or their ingredients and autism spectrum disorder (ASD). Get the #VaxFacts on vaccines and autism.
Side EffectsJust like any medication, vaccines can cause side effects. Most are mild and go away on their own. Some side effects common to all vaccines include:
- Redness, soreness or swelling at the injection site
- Low-grade fever
- Dizziness or fainting
Reporting Side EffectsThe Vaccine Adverse Effects Reporting Service (VAERS) is an early warning system set up by the CDC and FDA to detect possible safety issues. Anyone, including health care providers, nurses and parents, may report a reaction that occurs after a vaccination.
Paying for VaccinesMost health insurance providers cover all recommended vaccines. If you do not have health insurance or you can not afford the out-of-pocket costs for vaccines, there are low- and no-cost options available. Your local county health department has resources available to help you find free- or low-cost vaccines near you.
Vaccines for ChildrenThe Vaccines for Children (VFC) program provides free recommended vaccines for all children under the age of 19 who are:
- Eligible for Medicaid
- Uninsured or under-insured
- American Indian or Native Alaskan