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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.

2009 H1N1 Flu: International Situation Update

This report provides an update to the international flu situation using data collected through June 13, 2010, and reported by the World Health Organization (WHO) on June 18.

WHO continues to report laboratory-confirmed 2009 H1N1 flu deaths on its Web page. These fatal cases are an under-representation of the actual numbers as many deaths are never tested or recognized as flu related.
2009 H1N1 infections continue to be reported in parts of Central America, the Caribbean, South Asia and several countries Southeast Asia. In the temperate Southern Hemisphere, Chile and Uruguay are reporting a small number of 2009 H1N1 cases. Flu activity is increasing in Colombia, and low levels of flu activity have been reported in Costa Rica and Cuba.

Influenza type B is currently co-circulating with 2009 H1N1 in India and Bangladesh. Influenza A (H3N2) and influenza type B viruses have been reported in South Africa, and influenza A (H3N2) viruses continue to be reported in East Africa. Sporadic seasonal and 2009 H1N1 influenza viruses have been detected in Australia.

Selected Highlights

  • According to WHO, the majority of 2009 H1N1 virus isolates tested worldwide remains sensitive to oseltamivir, an antiviral medicine used to treat flu. Among 2009 H1N1 isolates tested worldwide, 298 have been found to be resistant to oseltamivir – as of May 28, 2010, 67 of these isolates were detected in the United States. Approximately 1% of U.S. 2009 H1N1 viruses tested by CDC since September 1, 2009, have been resistant to oseltamivir.
  • Influenza B continues to predominate in several countries, including China (Hong Kong SAR) (70.9% of all influenza detections), the Russian Federation (96.1%) and Ukraine (100%). H3N2 activity is also increasing in certain areas of East Africa and has been detected in China and the Russian Federation.
  • On February 18, 2010, WHO published recommendations for the following viruses to be used for influenza vaccines in the 2010-2011 influenza season of the Northern Hemisphere:
    • an A/California/7/2009 (H1N1)-like virus;
    • an A/Perth/16/2009 (H3N2)-like virus*;
    • a B/Brisbane/60/2008-like virus.

* A/Wisconsin/15/2009 is an A/Perth/16/2009 (H3N2)-like virus and is a 2010 Southern Hemisphere vaccine virus.

Health Organizations

World Health Organization (WHO) Regional Offices

Travel and 2009 H1N1 Flu

Human cases of 2009 H1N1 flu virus infection have been identified in the United States and several countries around the world. For information on 2009 H1N1 flu and travel, see the CDC H1N1 Flu and Travel website.

Reports and Publications

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