2011-2012 Seasonal Influenza (Flu) Vaccine Safety
What’s in the 2011-2012 seasonal flu vaccine and why?
Each year, the seasonal influenza vaccine contains three influenza viruses — one influenza A (H3N2) virus, one influenza A (H1N1) virus, and one influenza B virus. The 2009 H1N1 influenza virus strain is included in the 2011-2012 seasonal flu vaccine because scientists continue to see this virus strain circulate in the U.S.
Are the 2011-2012 seasonal flu vaccines safe?
This season’s flu vaccine is expected to have a similar safety profile as past seasonal flu vaccines. Over the years, hundreds of millions of Americans have received seasonal flu vaccines. The most common side effects found from the 2010-2011 flu vaccines were soreness, redness, tenderness or swelling where the flu shot was given and nasal congestion after the flu vaccine nasal spray.
The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are closely monitoring for any signs that the vaccine is causing unexpected adverse events and are working with state and local health officials and other public health partners to investigate any unusual events.
How will the safety of this seasonal flu vaccine be monitored?
CDC and FDA closely monitor the safety of seasonal influenza and other vaccines licensed for use in the United States, in cooperation with state and local health departments, healthcare providers, and other partners.
The purpose of vaccine safety monitoring is to quickly identify any clinically significant adverse events following immunization. Adverse events, including apparent side effects, following immunization may be coincidental to (meaning occurring around the same time but not related to vaccination) or caused by vaccination.
CDC and its partners use multiple systems to monitor the safety of this season’s flu vaccines. Two of the primary systems that are being used to monitor the safety of these vaccines are: the Vaccine Adverse Event Reporting System (VAERS), which is jointly operated with FDA, and the Vaccine Safety Datalink (VSD) Project.
Vaccine Adverse Event Report System (VAERS)
VAERS is a national program managed by both CDC and FDA to monitor the safety of all vaccines licensed in the United States. Anyone can file a VAERS report. VAERS relies on information included in these reports to monitor for clinically serious adverse events or health problems that follow vaccination. Healthcare providers are encouraged to voluntarily report possible adverse events of concern after vaccination, even if they are not certain that the vaccine caused the event. Generally, VAERS cannot determine if an adverse event was caused by a vaccine but can help determine if further investigations are needed. FDA and CDC use VAERS data to help identify potential clinically serious vaccine adverse events or health outcomes. If concerns are identified in VAERS, usually further investigation is needed. One important system used to further evaluate concerns identified in VAERS is the Vaccine Safety Datalink (VSD) Project. More information about VAERS is available.
Vaccine Safety Datalink (VSD) Project
The VSD Project is a vaccine safety system used to both identify and confirm adverse outcomes after immunization. This project is a collaboration between CDC and 8 large managed care organizations, in which comprehensive medical information is collected on approximately 9 million people. The VSD project monitors their data weekly for certain adverse events that could be associated with newly licensed vaccines. VSD conducts studies of vaccine safety adverse events and health outcomes that may arise with any vaccine.
Additionally, CDC works with numerous partners, including other federal agencies, state and local health departments, professional organizations, and academic institutions, to actively follow individuals after vaccination to monitor for any potential adverse events.
Are there any side effects to the seasonal flu vaccine?
A complete list of possible side effects from both the flu shot and the nasal spray (LAIV or Flu Mist) vaccines are below:
The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:
- Soreness, redness, or swelling where the shot was given
- Fever (low grade)
If these problems occur, they begin soon after the shot and usually last 1 to 2 days. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions. A federal program has been created to help pay for the medical care and other specific expenses of certain persons who have a serious reaction to this vaccine. For more information about this program, call 1-888-275-4772 or visit the program's website at Countermeasures Injury Compensation Program.
The nasal spray (also called LAIV): The viruses in the nasal-spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. (In clinical studies, transmission of vaccine viruses to close contacts has occurred only rarely.)
In children, side effects from LAIV can include:
- Runny nose
- Muscle aches
In adults, side effects from LAIV can include:
- Runny nose
- Sore throat
Mild problems that may be experienced include soreness, redness, or swelling where the shot was given, fainting (mainly adolescents), headache, muscle aches, fever, and nausea. If these problems occur, they usually begin soon after the shot and last 1-2 days. Life-threatening allergic reactions to vaccines are very rare. If they do occur, it is usually within a few minutes to a few hours after the shot is given. This season’s flu vaccine is made the same way as past seasonal flu vaccines. Millions of seasonal flu vaccines have been given safely. Millions of people have also safely received the 2009 H1N1 vaccine. CDC expects that any side effects following vaccination with the 2010-2011 flu vaccine would be rare. Any side effects that may occur are expected to be similar to those experienced following past seasonal influenza vaccine.
Are there symptoms that should cause concern after getting a flu vaccination?
Signs of a serious allergic reaction can include difficulty breathing, hoarseness or wheezing, swelling around the eyes or lips, hives, paleness, weakness, a fast heart beat or dizziness. In addition, after vaccination you should look for any unusual condition, such as a high fever or behavior changes. If any unusual condition occurs following vaccination, seek medical attention right away. Tell your doctor what happened, the date and time it happened, and when the vaccination was given. Ask your doctor, nurse, or health department to report a possible reaction by filing a Vaccine Adverse Event Reporting System (VAERS) form. Or you can file this report yourself through the VAERS website. You may call 1-800-822-7967 to receive a copy of the VAERS form. VAERS does not provide medical advice.
Are there some people who should not receive this vaccine?
People who have a severe (life-threatening) allergy to chicken eggs or to any other substance in the vaccine should not be vaccinated.
Centers for Disease Control and Prevention
Influenza (Flu) Vaccine