Swine flu science update 5 November

The WHO says that at least 16 of the world's poorest countries will receive batches of the A(H1N1) swine flu vaccine within the next few weeks.

Marie-Paule Kieny, the WHO's director of vaccine research, told a press briefing last week (30 October) that 156 million vaccine doses have been secured, largely through donations, and these will be distributed to 95 developing nations.

In line with recommendations from SAGE (Strategic Advisory Group of Experts on Immunization), health care workers will be vaccinated first.

Populations will need reassurance that the vaccine is safe, now that mass immunisation campaigns are underway, notes an article in The Lancet* last week(31 October).

The authors warn there is a tendency for the public to link new vaccines to unrelated but highly visible conditions — such as spontaneous abortion, Guillain-Barré syndrome or even death — when immunisation campaigns are not accompanied by reliable safety data.

However, at the same time, public health officials need to be on the lookout for serious adverse events resulting from new vaccines, the article says.

Ponies were used to deduce just how the influenza virus outwits the flu vaccine to cause illness in a study published in Science last week (30 October). Researchers studied vaccinated and non-vaccinated ponies infected with equine influenza and showed how changes in the amino acids of a virus' hemagglutinin protein (one of the main ways the virus evades the immune system) influence disease spread.

They say that following the molecular evolution of the influenza virus could inform the development of more effective vaccination strategies. They also point out that even an imperfect vaccine could be beneficial — if enough of a population is vaccinated.

In a similar study reported by The Associated Press last week (29 October), scientists found that regular immunisations against flu result in mice becoming infected by a 'stickier' version of the virus. Stickiness reflects mutations to the virus in response to 'antibody pressure' from the host's immune system — but a sticky flu strain does not spread as easily.

A controversial theory proposing that small children who fall ill with seasonal influenza will develop better immunity to A(H1N1) was published online in The Lancet Infectious Diseases* (30 October). Scientists from the Erasmus Medical Centre in the Netherlands debated the issue with colleagues from Finland's Turku University Hospital.

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