Content on this page was developed during the 2009-2010 H1N1 pandemic and has not been updated.
- The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.
- The English language content on this website is being archived for historic and reference purposes only.
- For current, updated information on seasonal flu, including information about H1N1, see the CDC Seasonal Flu website.
Vaccine Safety
January 4, 2010, 9:30 AM ET
The 2009 H1N1 influenza vaccines are showing similar safety profiles as seasonal flu vaccines, which have very good safety track records. Over the years, hundreds of millions of Americans have received seasonal flu vaccines. Millions of people have also safely received the 2009 H1N1 vaccine. 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) are closely monitoring for any signs that the vaccine is causing unexpected adverse events and are working with state and local health officials to investigate any unusual events.
- General Questions and Answers
- Fact Sheet: Safety of Thimerosal in Vaccines Against 2009 H1N1 Flu
- Questions and Answers on Thimerosal
- Questions and Answers on Guillain-Barré syndrome (GBS)
- Fact Sheet on Guillain-Barre syndrome (GBS)
- Questions and Answers about Adjuvants
Vaccine Monitoring
- How Vaccines are Tested and Monitored
- Vaccine Adverse Event Reporting System (VAERS)
- Summary of 2009 Monovalent H1N1 Influenza Vaccine Data --- VAERS
- VAERS Information for Healthcare Professionals
- Reporting Adverse Events to VAERS
- Template Letter for Healthcare Providers about the Vaccine Adverse Event Reporting System (VAERS)
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