Vaccine Safety Monitoring Systems for 2012-2013 Influenza Season

Questions & Answers

What is CDC doing to ensure the safety of influenza vaccines used in the United States?

Every year, CDC works closely with FDA, health care providers, state and local health departments, and other partners to ensure the highest safety standards for flu vaccines. CDC and FDA both share responsibility for monitoring the safety of vaccines and ensuring systems are in place to promptly detect unexpected health problems following vaccination.

At CDC, the Immunization Safety Office (ISO) leads most of the agency’s vaccine safety research and monitoring activities.

Over the past 50 years, flu vaccines have been shown to be safe.

What do CDC and FDA look for when monitoring the safety of U.S.-licensed vaccines?

The main goals for monitoring the safety of vaccines routinely recommended in the United States are to:

• Quickly identify new or rare adverse events, or health problems following vaccinations
• Monitor changes in patterns for known adverse events, especially increases in frequency or severity of such events.
• Assess safety in special populations (e.g., pregnant women and persons with some chronic health conditions).
• Determine if some persons are at greater risk for experiencing particular adverse events.
• Assess safety of vaccine lots (this activity is conducted by FDA).

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What happens each year during safety monitoring for influenza vaccinations?

The goals for monitoring the safety of influenza vaccines each year are the same as other vaccines. However, there are some additional considerations.

• First, the viruses included in the seasonal flu vaccine (vaccine formulation) change each year in order to update the vaccine with the most common circulating viruses. The 3 viruses included in the vaccine are selected months before the influenza season starts (in the February before the upcoming season).
• There are multiple inactivated influenza vaccines produced by different manufacturers. The live attenuated vaccine is produced by one manufacturer. See Table of Influenza vaccines recommended by the Advisory Committee on Immunization Practices (ACIP) for different age groups — United States, 2012–13 season.”
• In the past, from season to season, there may have been new populations recommended to receive influenza vaccine. Starting in 2010-2011, a universal influenza vaccination recommendation was adopted in the United States.
• There is special attention each year to monitor for possible risk of Guillain-Barré Syndrome (GBS) after influenza vaccine, a concern that arose during the 1976 “swine flu” vaccination program; however, studies of seasonal influenza vaccines in other years have shown either no increased risk or a very small increased risk.

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How will CDC and FDA get information from the public on any health problems people might experience after influenza vaccination?

The Vaccine Adverse Event Reporting System (VAERS) is one of two key systems used to monitor the safety of vaccines, including the influenza vaccines administered during 2012-2013. VAERS is a national program co-managed by CDC and FDA. It serves as an “early warning” system for potential vaccine safety concerns. VAERS receives about 30,000 reports annually of adverse events following immunizations from a variety of sources (such as patients, family members, health care providers, and vaccine manufacturers). Generally, VAERS cannot determine if a vaccine caused an adverse event, but can provide a signal for further investigation.

VAERS will be used during the 2012-2013 flu season to help detect any rare adverse events that need further study.

The Vaccine Safety Datalink (VSD) Project is the main system used to monitor the safety of 2012-2013 influenza vaccines. The VSD Project is managed and coordinated by CDC’s Immunization Safety Office. Ten large managed care organizations participate in this project, which monitors vaccination data on approximately 9 million people (about 3% of the U.S. population). From these data, project researchers are able to conduct formal studies of adverse events, including those potentially associated with new vaccines or changes in immunization schedules.

For the 2012-2013 flu season, the VSD Project will monitor for rare adverse events, as well as febrile seizures following vaccination.

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