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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

November 13, 2009, 4:30 PM ET

Map of International Activity Estimates
(Including 2009 H1N1 Flu)

This picture depicts a map of the world that shows the co-circulation of 2009 H1N1 flu and seasonal influenza viruses. The United States, Canada, Europe, Kenya, Japan and China are depicted. There is a pie chart for each that shows the percentage of laboratory confirmed influenza cases that have tested positive for either 2009 H1N1 flu or other influenza subtypes. The majority of laboratory confirmed influenza cases reported in the United States, Canada, Europe, Japan and China have been 2009 H1N1 flu.

This report provides an update to the international situation as of November 13, 2009. The World Health Organization (WHO) continues to report laboratory-confirmed 2009 H1N1 flu cases and deaths on its Web page. These laboratory-confirmed cases represent a substantial underestimation of total cases in the world, as many countries focus surveillance and laboratory testing only on people with severe illness. The 2009 H1N1 influenza virus continues to be the dominant influenza virus in circulation in the world. Since April 19, 2009, more than 65% of all influenza positive specimens reported to WHO have been 2009 H1N1. In temperate regions of the Southern Hemisphere, little disease activity due to 2009 H1N1 has been reported. In tropical regions of the Americas and Asia, influenza activity due to 2009 H1N1 remains variable. In temperate regions of the Northern Hemisphere, influenza-like illness (ILI) activity due to 2009 H1N1 continues to increase across many countries in Europe and Asia, as well as many areas of the United States, Mexico and Canada.

Selected Highlights

  • The 2009 H1N1 influenza virus is the predominant influenza virus in circulation in most countries worldwide.
  • The epidemiology of disease caused by 2009 H1N1 influenza in the Southern Hemisphere is very similar to that described in the United States in the spring of 2009.
  • There have been no significant changes detected in the 2009 H1N1 influenza viruses isolated from persons in the Southern Hemisphere as compared to viruses isolated from persons in the Northern Hemisphere.
  • According to WHO, the majority of 2009 H1N1 influenza isolates tested worldwide remain sensitive to oseltamivir, an antiviral medicine used to treat influenza disease. 52 2009 H1N1 isolates tested worldwide have been found to be resistant to oseltamivir – 15 of these isolates were detected in the United States.
  • On September 17, 2009, several countries including the United States announced plans to donate 2009 H1N1 vaccine or funds to support vaccination campaigns in less developed countries.

International Resources for 2009 H1N1 Information

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.

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