Each year, the seasonal influenza vaccine contains three flu
viruses -- one influenza A (H3N2)
virus, one influenza A (H1N1) virus, and one influenza B virus. The 2009 H1N1
(swine) flu) virus strain is included in the 2010-2011 seasonal flu vaccine
because scientists continue to see this virus strain circulate in the U.S.
This season's 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 last year's H1N1 flu
vaccines were soreness, redness, tenderness or swelling where the flu shot was
given and nasal congestion after the flu vaccine nasal spray.
Feds to monitor vaccine
The Centers for Disease Control and Prevention (CDC) and the
Food and Drug Administration (FDA) are closely monitoring for any signs 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.
The purpose of vaccine safety monitoring is to provide quick
identification of 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 elated 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 is a national program managed by both CDC and FDA to
monitor the safety of all vaccines licensed in the United States. Healthcare
providers are encouraged to report possible adverse events of concern after
vaccination, even if they are not certain that the vaccine caused the event.
VAERS relies on information included in these reports to monitor for clinically
serious adverse events or health problems that follow vaccination.
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.
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 eight large managed care organizations, in which
comprehensive medical information is collected on approximately nine 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.
Vaccine side effects
Both the flu shot and the nasal spray (LAIV or Flu Mist)
vaccines have possible side effects. Among them:
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)
- Aches
- Nausea
If these problems occur, they begin soon after the shot and
usually last a day or two. Almost all people who get flu shots have no serious
problems. However, on rare occasions, they 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.
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
- wheezing
- headache
- vomiting
- muscle aches
- fever
In adults, side effects from LAIV can include:
- runny nose
- headache
- sore throat
- cough
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.
Cause for concern
Signs of a serious allergic reaction can include difficulty
breathing, hoarseness or wheezing, swelling around the eyes or lips, hives,
paleness, weakness, a fast heartbeat 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 or by calling 1-800-822-7967 to receive a copy of the VAERS form.
