Emergencies preparedness, response

Pandemic (H1N1) 2009 - update 71

Weekly update (Virological surveillance data)

The Global Influenza Surveillance Network (GISN) continues to monitor the global circulation of influenza viruses, in particular those infecting or with the potential of infecting humans, including seasonal influenza.

Since the beginning of the pandemic in 19 April 2009 to October 10th, a total of 80 countries have reported to FluNet. The total number of specimens reported as positive for influenza viruses by NIC laboratories was 151,070. Of these, 93,450 (61.9%) were pandemic H1N1, 6821 (4.5%) were seasonal A (H1), 19,800 (13.1%) were A (H3), 26,461 (17.5%) were A (Not subtyped) and 4538 (3%) were influenza B.

For this reporting week (4 October to 10 October 2009); a total of 27 countries reported to FluNet. The total number of specimens reported as positive for influenza viruses by NIC laboratories was 6934. Of these, 4526 (65.3%) were pandemic H1N1, 43 (0.6%) were seasonal A (H1), 249 (3.6%) were A (H3), 1985 (28.6%) were A (Not subtyped), 131 (1.9%) were influenza B.

Systematic surveillance conducted by the Global Influenza Surveillance Network (GISN) including WHO Collaborating Centres (WHOCCs) for reference and research on influenza, continues to detect sporadic incidents of H1N1 pandemic viruses that demonstrate resistance to the antiviral oseltamivir. To date, 39 resistant pandemic H1N1 influenza viruses have been detected and characterized worldwide. All of these viruses show the same H275Y mutation that confers resistance to the antiviral oseltamivir, but not to the antiviral zanamivir. Worldwide, more than 10,000 clinical specimens (samples and isolates) of the pandemic H1N1 virus have been tested and found to be sensitive to oseltamivir.

All pandemic H1N1 2009 influenza viruses analysed to date were antigenically and genetically closely related to the vaccine virus A/California/7/2009.

Virology data update

Download update (.pdf)

For more information