- Condition Centers
How Do Vaccines Work?
Antibodies are proteins in your body that fight viruses and bacteria. After a vaccine is given, the body makes antibodies against the weakened or killed virus or bacteria. These antibodies stay in your body's immune system "memory." They will fight off infection if you are exposed to that same virus or bacteria in the future. This "memory" lasts a lifetime with some vaccines. But protection from some viruses and bacteria can decrease over time. Because of this, you may have to get some vaccines more than once.
Why Should I Get Vaccines?
Vaccines are important for you and for the public as a whole. Since the time that vaccines were first used, fewer people have become sick or died. This is because many diseases can be prevented with vaccines today. Some examples of these diseases are measles, mumps, whooping cough, and polio. Vaccines prevent people from feeling sick, make people able to carry out their daily activities, and prevent death. They help stop the spread of infections to large groups of people, even to people who have not gotten the vaccine.
Are There Risks Associated With Vaccines?
Before a vaccine can be given to the public, it must be approved by the Food and Drug Administration (FDA) - which means that it has been tested and proven to be effective and safe. The FDA and the Centers for Disease Control and Prevention (CDC) are always collecting information on the safety of vaccines to make sure that vaccines are given in the safest way possible.
Vaccines offer many benefits, but no vaccine is 100% safe and effective. Vaccines can cause minor side effects, such as fever or pain at the place on the body where the injection was given. These reactions are not dangerous and will go away on their own. More serious side effects, such as an allergic reaction, are rare. Signs of a serious allergic reaction are difficulty in breathing, wheezing, hives, weakness, dizziness, swelling in the neck or throat, or fast heartbeat. Be sure to tell your health care provider if you are allergic to any medications or foods before you get a vaccine.
Most serious reactions happen soon after a person gets the vaccine. If you get more than 1 vaccine at a time, this does not increase your risk of having a side effect. If you think that someone is having an allergic reaction to a vaccine, you should take him or her to a doctor right away.
How Do I Know Which Vaccines I Need?
The CDC studies information on infections and decides who should receive certain vaccines and when they should receive them. The CDC releases these recommendations each year. Whether you need a vaccine and when you should get it are based on your age and your risk of getting the disease that the vaccine protects against. Your doctor or other health care provider will recommend vaccines based on information from the CDC, which vaccines you have received in the past, and your own personal medical history. You also may need extra vaccines if you are traveling outside of the country. Make sure you get your vaccines when your doctor or health care provider asks you to, so that they will do the best job of protecting you from viruses and bacteria.
Who Should Not Get Vaccines?
You should not get a vaccine if you had a severe allergic reaction to that vaccine in the past. Also, women who are pregnant or anyone who has a lessened ability to fight infections should not receive some vaccines. There are other reasons that a person should not get certain vaccines. Therefore, be sure to tell your health care provider if you are allergic to any foods or medications, or if you have had an allergic reaction to a vaccine in the past.
Can I Get a Vaccine If I Have Been Sick Recently?
You can get vaccines if you have a slight sickness, such as a cold, diarrhea, or other sickness with a low fever. If you have had a more severe sickness, then you should wait to get vaccines until after you have recovered from this sickness.
Where Can I Get More Information?
The information in the handout is about vaccines in general. You also may decide to research important information about each available vaccine. If you have questions, ask a trusted health care professional, such as your doctor, nurse, or pharmacist. You can also call the CDC Information Center at 800-CDC-INFO or 800-232-4636, or go to the Web site, www.cdc.gov/nip.