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Monday, March 28, 2011

WHO : Influenza update - 25 March 2011

The latest influenza update from WHO, excerpt :

" Update number 130


Influenza activity in most areas of the northern hemisphere temperate regions appears to have peaked and is declining. Although the level of pneumonia and influenza mortality in the United States of America (USA) is above the epidemic threshold and many states still are reporting on widespread activity, most indicators on influenza activity in North America are indicating decreasing influenza activity. As activity in the Americas declines, influenza A(H1N1)2009 has increased proportionately and now accounts for 38% of all virus detections.

In Europe the peak has been passed in most countries and all countries now report medium or low influenza activity. Cases of Severe Acute Respiratory Infections in Europe are decreasing but still above baseline in some parts of Eastern Europe. Influenza viruses in Europe continue to be primarily influenza A(H1N1)2009, about 70% of all viruses characterized, and influenza type B, making up about 28% of all viruses.

Data from parts of Northern Africa show that there is ongoing community transmission of both influenza A(H1N1l)2009 and influenza type B in Tunisia and Algeria. The large majority of the viruses characterized are closely related to the vaccine strains included in the current seasonal vaccines.

Viruses which have been characterized antigenically continue to be largely related to the lineages found in the current trivalent seasonal vaccine except for a small number of influenza B viruses of the Yamagata lineage."

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