Influenza Vaccine Questions & Answers from the Centers for Disease Control and Prevention (CDC)

• Q&A: Flu Vaccine
• Q&A: Thimerosal-Containing Influenza Vaccine
• Q&A: Nasal Spray Flu Vaccine 
• Q&A: Influenza Vaccine Production, Supply & Distribution in the U.S.
• Misconceptions about Influenza and Influenza Vaccine

2009 - 2010 Influenza Vaccine Strains

Both the inactivated and the live, attenuated influenza vaccine prepared for the 2009-10 season will include:

• an A/Brisbane/59/2007 (H1N1)-like virus;
• an A/Brisbane/10/2007 (H3N2)-like virus;
• a B/Brisbane 60/2008-like virus.

These viruses will be used because they are representative of influenza viruses that are anticipated to circulate in the United States during the 2009-10 influenza season and have favorable growth properties in eggs.

The inactivated influenza vaccine (the "flu shot") is FDA-approved for persons 6 months of age and older, including those with high-risk conditions, whereas the live, attenuated influenza vaccine (the nasal-spray flu vaccine) is FDA-approved for use only among healthy, non-pregnant persons aged 2 to 49 years. All children aged 6 months through 8 years who are receiving flu vaccine for the first time should receive 2 doses of vaccine.  Children 6 months through 8 years who received flu vaccine for the first time during the previous influenza season, and got only one dose, should receive 2 doses this season.  Children who were given influenza vaccine during any other prior flu season should receive only one dose.