Vaccines Approved for H1N1 Influenza Virus
The U.S. Food and Drug Administration (FDA) has approved four vaccines for use against the 2009 H1N1 influenza virus.
The vaccines—made by CSL Limited, MedImmune LLC, Novartis Vaccines and Diagnostics Limited, and sanofi pasteur Inc.—will be distributed nationally after the initial lots become available. This is expected to occur within the next four weeks.
Commissioner of Food and Drugs Margaret A. Hamburg, M.D., says the approval is good news for the nation's response to the 2009 H1N1 influenza virus. "The vaccine will help protect individuals from serious illness and death from influenza," she says.
Vaccines against three seasonal virus strains are already available and should be used. However, they do not protect against the 2009 H1N1 virus.
What have studies of the H1N1 vaccines shown?
Based on preliminary data, the approved vaccines induce a robust immune response in most healthy adults eight to 10 days after a single dose, as occurs with the seasonal influenza vaccine.
Clinical studies under way will provide more information about the optimal dose in children. Recommendations for dosing will be updated if indicated by findings from those studies. The findings are expected in the near future.
What are the warnings and potential side effects?
In the ongoing clinical studies, the 2009 H1N1 vaccines have been well tolerated. However, consumers need to be aware of the following:
• People with severe or life-threatening allergies to chicken eggs, or to any other substance in the vaccine, should not be vaccinated.
• Potential side effects of the H1N1 vaccines are expected to be similar to those of seasonal flu vaccines. For the injected vaccine, the most common side effect is soreness at the injection site. Other side effects may include mild fever, body aches, and fatigue for a few days after the inoculation. For the nasal spray vaccine, the most common side effects include runny nose or nasal congestion for all ages, sore throats in adults, and—in children 2 to 6 years old—fever. (Also see seasonal flu information in the "For More Information" section below.)
• As with any medical product, unexpected or rare serious adverse events may occur.
FDA is working closely with other agencies to enhance adverse-event monitoring, information sharing, and analysis during and after the 2009 H1N1 vaccination program. In the U.S. Department of Health and Human Services, these agencies include the Centers for Disease Control and Prevention (CDC).