Do vaccines have side effects? What reactions are considered serious?
As is the case with any medication, vaccines can have side effects. However, the majority of vaccine side effects are very mild, such as soreness or redness where the vaccine was given, or a low-grade fever. These side effects usually go away within a few days. Serious side effects following vaccination are very rare occurring 1 in a million doses, and would happen within a few minutes to a few hours after the vaccination.
In general, parents should pay extra attention to their children’s overall health for a few days after vaccination (and your own health if you have been vaccinated). If you notice something that concerns you, call your healthcare provider.
Watch this video from CDC to see what to expect when your child gets vaccinated.
When deciding whether or not to vaccinate your family members, remember that the diseases from which your family is being protected can be very dangerous or even deadly. Even though many of these diseases are rare in the United States, they still occur around the world and unvaccinated people who travel to other countries can bring these diseases to the U.S., placing unvaccinated people at risk. One example of this was the large, multi-state measles outbreak that started in Disneyland in California. The outbreak began from a person who became infected with measles when traveling overseas, and then, while still infectious, visited Disneyland. The majority of people – 188 people in 24 states and DC – who ended up sick with measles were unvaccinated.
It is very important to weigh the science-based risks versus benefits of vaccines. For instance, while a sore arm, or a fever and fussiness in your child after being vaccinated is never easy, it means that the vaccine is working by creating an immune response (protection) that may last a lifetime.
The CDC’s Vaccine Information Statements (VIS), which are created for every vaccine recommended in the United States, explain both the benefits and risks of the vaccines.
What do I do if my child has a serious reaction to a vaccine?
If you are concerned that your child has had a serious reaction to a vaccine, call your healthcare provider or 911 immediately. Most people who get vaccinated have no serious after effects. However, vaccines, like any medicines, can cause side effects. Most of these side effects are very mild like a low fever. If your child experiences a reaction at the vaccine injection site, use a cool, wet cloth to reduce redness, soreness, and swelling. Speak to your healthcare provider about fever/pain reducing medicines.
In very rare cases, a vaccine can cause a serious problem, such as a severe allergic reaction. Its important to note that some health problems that follow vaccinations are not necessarily caused by the vaccines, but if you notice something that concerns you, call your child’s healthcare provider.
The CDC’s Vaccine Information Statements (VIS), which are created for every vaccine recommended in the United States, explain both the benefits and risks of the vaccines and how to report any serious side effects.
If your child received a recommended vaccine and you believe he or she was injured as a result, you can file a report in the Vaccine Adverse Event Reporting System and you may file a legal claim with the National Vaccine Injury Compensation Program (VICP). The VICP may provide financial compensation to individuals who file a petition and are found to have been injured by a covered vaccine.
What if an adult or pregnant woman has a serious reaction to a vaccine?
If you are concerned about a serious reaction to a vaccine, call your healthcare provider or 911 immediately.
The CDC’s Vaccine Information Statements (VIS),which are created for every vaccine recommended in the United States, explain both the benefits and risks of the vaccines and how to report serious side effects.
The CDC’s Advisory Committee for Immunization Practices (ACIP) recommends vaccines for people of all ages, and they are tested before and after being licensed by the FDA for use in the United States. Serious side effects from vaccines are very rare, but if you are concerned about any health problems after vaccination, you should contact your healthcare provider right away. Any person who received a recommended vaccine and believes he or she was injured as a result, can file a report in the Vaccine Adverse Event Reporting System.
Any adult who received a vaccine that is also routinely recommended for children (i.e. flu, pertussis) and believes he or she was injured as a result, can file a petition with the National Vaccine Injury Compensation Program (VICP). There are no age restrictions.
The CDC’s ACIP, the American College of Obstetricians and Gynecologists (ACOG) and the American College of Nurse-Midwives recommend flu and whooping cough (Tdap) vaccines for all pregnant women. These vaccines have been studied and have been shown to be safe for pregnant women and their babies. However, in case of a rare serious reaction to the vaccine, a pregnant woman can file a claim for herself or her baby within the National Vaccine Injury Compensation Program (VICP).
Who monitors the safety of vaccines in the United States?
Before being approved for use in the people of all ages, vaccines are required to go through a lot of testing. Clinical trials are performed before the vaccine is made available to confirm the vaccine’s safety and efficacy (the ability to produce the intended result)– both as an individual vaccine and when it is given with other vaccines according to the recommended vaccine schedule.
Even after a vaccine receives FDA-approval and is recommended for use by the CDC, post-licensure studies are done on an ongoing basis to continually monitor the vaccine’s safety, and to detect and respond to any rare adverse events. The CDC and FDA monitor and evaluate the safety of vaccines through the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD), the Clinical Immunization Safety Assessment Project (CISA) and the Post-Licensure Rapid Immunization Safety Monitoring System (PRISM).
VAERS is a passive reporting system. That means it relies on individuals to report vaccine reactions. Anyone can report a reaction or injury, including healthcare providers, patients and patients’ representatives, such as caregivers or attorneys. The system is co-managed by the FDA and the CDC. However, it is important to note that VAERS data alone can’t be used to answer the question, “Does a certain vaccine cause a certain side effect?” This is because adverse events reported to VAERS may or may not be caused by vaccines. There are reports in VAERS of common conditions that occur just by chance after vaccination. Further investigation may find no medical link between vaccination and these conditions. Instead, the purpose of VAERS is to see if unexpected or unusual patterns emerge, which may indicate a vaccine safety issue that needs to be researched further.
Established in 1990, VSD is a collaboration between the CDC’s Immunization Safety Office and eight health care organizations across the country. It conducts studies based on questions or concerns raised from the medical literature and reports to VAERS. In addition, when new vaccines are recommended or if changes are made in how a vaccine is recommended, VSD will monitor the safety of these vaccines.
CISA, which was created in 2001, is a national network of vaccine safety experts from the CDC’s Immunization Safety Office, seven medical research centers and other partners. CISA addresses vaccine safety issues, conducts high quality clinical research and assesses complex clinical adverse events following vaccination. CISA also helps to connect clinicians with experts who can help consult on vaccine safety questions related to individual patients.
PRISM is a partnership between the FDA’s Center for Biologics Evaluation and Research and health insurance companies. It actively monitors and analyzes data from a representative subset of the general population. PRISM links data from health plans with data from state and city immunization information systems (IIS). PRISM has access to information for over 190 million people allowing it to identify and analyze rare health outcomes that would otherwise be difficult to assess.
Can the flu shot give me the flu?
No. The way that flu shots are made they cannot cause the flu. Flu shots are made from either flu viruses that have been ‘inactivated’ (killed) OR a single gene from a flu virus (instead of the full virus) so they can create an immune response without causing a flu infection.
While some people may get mild side effects from the flu shot like a sore arm, a headache, muscle aches or a low fever, those side effects usually begin soon after the shot and only last 1 -2 days.
Learn more about the current flu season.
Why do some people not feel well or feel like they have flu symptoms after getting the flu vaccine?
The most common side effects from flu shots are soreness, redness, tenderness or swelling where the shot was given. Some people also report having a low fever, headache and muscle aches. If these reactions occur, they usually begin soon after getting the shot and last 1-2 days.
Besides side effects, there are several reasons why someone might get flu symptoms, even after they have been vaccinated against flu.
- Some people can become ill from other respiratory viruses besides flu such as rhinoviruses, which are associated with the common cold, cause symptoms similar to flu, and also spread and cause illness during the flu season. The flu vaccine only protects you from the flu, not other illnesses.
- It is possible to be exposed to influenza viruses, which cause the flu, shortly before getting vaccinated or during the two-week period after vaccination that it takes the body to develop immune protection. This may result in a person becoming ill with flu before protection from the vaccine takes effect.
- Some people may experience flu like symptoms even after getting vaccinated because they were exposed to a flu virus that is very different from the viruses the vaccine is designed to protect against. The ability of a flu vaccine to protect a person depends largely on the “match” between the viruses selected to make the flu vaccine that season and those spreading and causing illness. There are many different flu viruses that spread and cause illness among people.
- The flu vaccine can vary in how well it works season to season, and sometimes people who get vaccinated may still get sick. However, the flu vaccine still offers important benefits. It will:
- Reduce the severity of your illness if you got vaccinated, but still get sick from flu.
- Reduce the risk of children dying from flu.
- Reduce the risk of flu-associated hospitalization for children and adults.
- Help protect people around you, including those who are more vulnerable to serious flu illness due to age and/or certain chronic health conditions.
- Help protect people with certain chronic conditions from serious health complications.
- Help protect women during and after pregnancy.