Pandemic (H1N1) 2009 - update

13 December 2009, worldwide more than 208 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 10582 deaths.
WHO is actively monitoring the progress of the pandemic through frequent consultations with the WHO Regional Offices and member states and through monitoring of multiple sources of data.


In the temperate zone* of the northern hemisphere, transmission of pandemic influenza virus remains active and geographically widespread, however disease activity has peaked or passed its peak in many places, particularly North America. Influenza activity continues to increase in later affected areas of south-eastern and central Europe, and in central and south Asia.



In United States and Canada, active influenza transmission persists but overall levels of ILI** have declined substantially to near seasonal baselines. In the US, proportional mortality due to pneumonia and influenza (P&I mortality) has remained consistently elevated above the epidemic threshold for the past 10 weeks; however, weekly numbers of lab-confirmed hospitalizations and deaths continue to decline over the past month.
The preliminary analysis of data from Northern Hemisphere countries that have now passed through an entire season of winter transmission indicate that the mortality rate, as expressed in fatal cases per million people, is in the same range as that which was observed in the Southern Hemisphere winter. This would indicate that the overall severity of the pandemic has not changed although the proportion of the population infected has been much higher in the temperate countries of the Northern Hemisphere during their winter season compared to the circulation observed in their summer season.
In Europe, geographically widespread and active transmission of pandemic influenza virus continued to be observed across the continent. At least 10 countries, mostly in western and northern Europe, reported declining respiratory disease activity. During the last reporting period, ILI/ARI activity continued to increase or reach a plateau in a limited number of countries: the Czech Republic, Estonia,, Hungary, Montenegro and Switzerland (a range of 28-71% of sentinel respiratory samples were positive for influenza in these countries). A high intensity of respiratory disease activity was reported in parts of northern and south-eastern Europe and in parts of the Russian Federation. 99% of subtyped influenza A viruses in Europe were pandemic H1N1 2009. Detections of RSV in Europe continued to increase over the past five weeks, partially accounting for elevated ILI activity among young children in some countries.