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.
Novel H1N1 Flu: International Situation Update
August 7, 2009, 11:00 AM ET
This situation report provides an update to the international situation as of August 4, 2009. World Health Organization (WHO) regions have reported 162,380 laboratory-confirmed cases of novel influenza A (H1N1) and 1,154 deaths. The laboratory-confirmed cases represent an underestimation of total cases in the world as many countries have shifted to strategies of clinical confirmation and prioritization of laboratory testing for only persons with severe illness and/or high risk conditions. The novel influenza A (H1N1) virus is the dominant influenza virus in circulation in the United States, England, South Africa, New Zealand, Australia, Chile, Argentina and Brazil. South Africa has had a notable increase in the proportion of influenza that is novel influenza A (H1N1), and now it represents the majority of influenza in the country. Many seasonal influenza viruses from these countries have not been subtyped. Of those that have been subtyped in Australia, South Africa, and Argentina, the most common seasonal influenza virus is influenza A (H3N2).
- Novel influenza A (H1N1) continues to circulate widely.
- Descriptive epidemiology of cases remains similar across countries.
- Isolates sequenced at WHO and CDC suggest that circulating novel influenza A (H1N1) viruses look similar to A/California/07/2009 (the reference virus selected by WHO as a potential candidate for novel influenza A (H1N1) vaccine).
International Resources for Novel H1N1 Information
- World Health Organization (WHO)
- ECDC (European Centre for Disease Prevention and Control)
- H2P (Humanitarian Pandemic Preparedness)
- Public Health Agency of Canada
World Health Organization (WHO) Regional Offices
- AFRO (WHO Regional Office for Africa)
- AMRO (WHO Regional Office for the Americas) / PAHO (Pan American Health Organization)
- EMRO (WHO Regional Office for the Eastern Mediterranean)
- EURO (WHO Regional Office for Europe)
- SEARO (WHO Regional Office for South-East Asia)
- WPRO (WHO Regional Office for the Western Pacific)
Travel and Novel H1N1 Flu
Human cases of novel H1N1 flu virus infection have been identified in the United States and several countries around the world. For information on novel H1N1 flu and travel, see the CDC H1N1 Flu and Travel website.
Reports and Publications
- ECDC Interim Risk Assessment Influenza A (H1N1) 2009 Pandemic
Issued July 30, 2009 - This document provides an interim risk assessment of novel H1N1 flu in Europe prepared by ECDC.
- World Health Organization Weekly Epidemiological record – Issued July 24, 2009
This document by WHO provides updates on the international novel H1N1 flu situation.
- MMWR – Update: Novel Influenza A (H1N1) Virus Infection – Mexico, March-May, 2009 – Issued June 5, 2009 / Vol. 58 / No. 21.
This Morbidity and Mortality Weekly Report describes the novel influenza A (H1N1) outbreak in Mexico from March-May, 2009.
- MMWR – Update: Novel Influenza A (H1N1) Virus Infections – Worldwide, May 6, 2009 – Issued May 8, 2009 / Vol. 58 / No. 17.
This Morbidity and Mortality Weekly Report describes worldwide novel influenza A (H1N1) infections as of May 6, 2009.
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