H1N1 Frequently asked questions

Provided by CDC

The first doses of vaccines that protect against 2009 H1N1 influenza (flu) are now available, and more doses will be shipped in the upcoming weeks. As you are preparing to protect yourself and your family from the 2009 H1N1 flu, you may have questions about the safety of the 2009 H1N1 flu vaccines. Here are the Frequently Asked Questions about the Safety of the 2009 H1N1 Flu Vaccines.

1. Are the 2009 H1N1 influenza vaccines safe?

The 2009 H1N1 vaccines have undergone all the safety testing and quality checks that are usually done for other vaccines. We expect the 2009 H1N1 influenza vaccine to have a similar safety profile as seasonal flu vaccines, which have a very good safety track record. Over the years, hundreds of millions of Americans have received seasonal flu vaccines. The most common side effects following flu vaccinations are mild, such as soreness, redness, tenderness or swelling where the shot was given.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) will be closely monitoring for any signs that the 2009 H1N1 vaccine is causing unexpected adverse events, and we will work with state and local health officials to investigate any unusual events.

2. How will the 2009 H1N1 influenza vaccines be monitored for safety?

CDC and FDA closely monitor the safety of all vaccines licensed for use in the United States in cooperation with state and local health departments, healthcare providers, manufacturers, and other partners.

The purpose of vaccine safety monitoring is to quickly identify significant adverse events following immunization that may be worrisome enough to consider changing vaccine recommendations. Adverse events, or health problems, 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 are using multiple systems to monitor the safety of 2009 H1N1 influenza vaccine. Two of the primary systems are the Vaccine Adverse Event Reporting System (VAERS), which is jointly operated with FDA, and the Vaccine Safety Datalink (VSD) Project.

CDC also is collaborating with partners through the Emerging Infections Program to enhance monitoring of Guillain-Barré syndrome (GBS) during the 2009-10 flu season. For more information on this initiative, see the frequently asked questions