Tuesday, March 8, 2011

Flu trends

Google has been tracking flu trends for some time by analyzing people's choice of search terms. This method has been very successful and they can usually pick up trends a few weeks before the CDC data. In 2009 a variety of workers from Google and one from the CDC published a paper in Nature describing their technique: Detecting influenza epidemics using search engine query data.

For epidemiologists, this is an exciting development, because early detection of a disease outbreak can reduce the number of people affected. If a new strain of influenza virus emerges under certain conditions, a pandemic could ensue with the potential to cause millions of deaths (as happened, for example, in 1918). Our up-to-date influenza estimates may enable public health officials and health professionals to better respond to seasonal epidemics and pandemics. 
The graph above shows, for the United States as a whole, that the peak flu season is usually in February and that we are probably past the peak this year. You can also see how unusual last year was, pandemic years are always different. The big peak in October is from 2009-2010. The same pattern was seen in California except that our peak flu season seems a bit less predictable.

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