Summary of the 2009-2010 influenza season

Details

• Corporate Authors:
  National Center for Immunization and Respiratory Diseases (U.S.)
• Description:
  Flu seasons are unpredictable in a number of ways, including when they begin, how severe they are, how long they last and which viruses will spread. There were more uncertainties than usual going into the 2009-2010 flu season because of the emergence of the 2009 H1N1 influenza virus (previously called “novel H1N1” or “swine flu”) in the spring of 2009. This virus caused the first influenza pandemic (global outbreak of disease caused by a novel influenza virus) in more than 40 years. The United States experienced its first wave of 2009 H1N1 activity in the spring of 2009, followed by a second, larger wave of 2009 H1N1 activity in the fall and winter, during typical “flu season” time for the U.S. For information about 2009 H1N1 flu, visit the CDC 2009 H1N1 Flu website.
  
  The 2009-2010 flu season began very early, with 2009 H1N1 viruses predominating and causing high levels of flu activity much earlier in the year than during most regular flu seasons. Activity peaked in October and then declined quickly to below baseline levels by January. While activity was low and continuing to decline, 2009 H1N1 viruses were still reported in small numbers through the spring and summer of 20101. Additional information about flu activity during the 2009-2010 season can be found in the MMWR article Update: Influenza Activity – United States, 2009-10 Season.
  
  1 Mustaquim, D et al. Update: Influenza Activity – United States, 2009-10 Season. 2010; 59: 901-908.
  
  
• Content Notes:
  What was the 2009-2010 flu season like?
  
  When did the flu season peak?
  
  How severe was the season? -- How is severity characterized? -- How effective is the seasonal flu vaccine? -- What did CDC do to monitor effectiveness of flu vaccines for the 2009-10 season? -- Were last season's vaccines a good match for circulating viruses? -- Why were two vaccines needed last season? -- What did CDC do to monitor antiviral resistance in the United States during the 2009-10 season?.
  
  
• Subjects:
  Disease Outbreaks Influenza, Human Influenza Vaccines
• Document Type:
  Webpage
• Place as Subject:
  United States
• Collection(s):
  Stephen B. Thacker CDC Library
• Main Document Checksum:
  urn:sha256:f98748a9e522cd084a79c22f1b677e38e5e8cacc44181bed1927153aa0fc628d
• Download URL:
  https://stacks.cdc.gov/view/cdc/110211/cdc_110211_DS1.pdf
• File Type:
  [PDF - 71.98 KB ]