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  • Swine flu science update: 4 December 2009

One of the great unknowns about swine flu — how many people have been infected by the virus — will become clear as countries begin testing blood samples.

Only a tiny fraction of cases can be confirmed by laboratory tests, so public-health authorities must infer numbers from people reporting symptoms to their doctors.

But countries including France, the United Kingdom, the United States and Vietnam have started testing blood samples for antibodies to A(H1N1), Nature reported (24 November).

A genetic mutation has been found in A(H1N1) that killed two people in France, AFP reported last week, and the WHO confirmed that two deaths in Norway were caused by mutated versions of the virus.

Similar mutations have been observed in Brazil, China, Japan, Mexico, Ukraine and the United States.
Keiji Fukuda, the WHO's pandemic influenza special advisor, told press that mutations to the virus are common and must be monitored.

"If every mutation out there was reported, it would be like reporting changes in the weather," he said. He added that when mutations are reported, the WHO assesses how they affect the overall clinical picture.

An article in New Scientist has said (25 November) fears that the mutation found in Norway signalled the evolution of A(H1N1) into something more deadly were premature. The mutation — which may allow the virus to infect deeper into the lungs — doesn't make it more likely to cause severe disease, it said. The mutation has been found in mild strains of flu and does not seem to have spread.

Zhong Nanshan, director of China's Guangzhou Institute of Respiratory Diseases, said China must be vigilant in monitoring genetic changes to influenza viruses because the country has both H5N1 bird flu and A(H1N1).
"This could produce a flu virus that is as deadly as the former and as contagious as the latter," he warned.
Reuters reported in the same article that China's health ministry has threatened severe punishment for officials concealing A(H1N1) flu deaths.

Pigs in Norway may have contracted A(H1N1) from people, Eurosurveillance reported (12 November). Norwegian authorities are monitoring affected farms and have restricted the movement of their animals over fears that the pigs could become reservoirs for the virus — providing a vessel in which A(H1N1) could combine with other influenza viruses — and re-infect humans.

Egypt is to make its own A(H1N1) drugs, the country's health ministry has announced. Reuters reported (25 November) that Egypt will license five companies to produce five million doses of generic drugs in 2010.

The Netherlands is selling 19 million doses of the A(H1N1) vaccine it ordered from pharmaceutical companies, ScienceInsider reported (28 November). The Dutch government ordered the vaccine when it thought people would need two doses, but research subsequently showed that one dose is enough.

However, Japanese and Dutch researchers suggested this month (12 November) in Eurosurveillance that a single dose of vaccine should be provided only where there is a shortage of vaccine.

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