Swine flu science update: 4 January 2010

The developing world is still waiting for swine flu vaccine Copyright: Flickr/Madmoiselle Lavender

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The WHO director-general, Margaret Chan, has said that the swine flu — influenza A(H1N1) — pandemic may not be conquered until 2011.

She said it was "prudent and appropriate" to monitor the evolution of the virus for the next 12 months, Reuters reported last week (29 December).

Cases have peaked in the United Kingdom, Canada and the United States, she said, but are still increasing in countries such as Egypt and India.

Keiji Fukuda, the WHO’s special advisor on swine flu, said last month (19 December) that logistical and regulatory issues caused delays in distributing A(H1N1) vaccines to the developing world [46kB].

The organisation had planned to start sending vaccine in November, with Afghanistan, Azerbaijan and Mongolia first in line, said Fukuda.

Chan added that the decision by AstraZeneca and Sanofi-Aventis to recall some A(H1N1) vaccine because it was not potent enough was not related to vaccine safety.

As vaccine becomes increasingly available, the required number of doses is still being debated. The Lancet published three studies last month (16 December) from China* and Hungary* and the United States*. All three say that one dose is enough for an adult but that children (under nine in the US study and under 12 in the Chinese study) need two. The Hungarian study did not include children.

But an Australian study, to be published in the Journal of the American Medical Association this week (6 January), found that one dose is effective in children older than six months.

The New England Journal of Medicine reported last month (31 December) that young people are more likely to catch A(H1N1) — but are not more likely to spread it.

People under 18 are twice as likely to catch swine flu from members of their household than those aged 19–50 but are no more likely to pass it on.

US scientists have mapped the interaction between human and A(H1N1) cells. Their study, published in Cell (17 December), will guide future studies, they said.

And a small human protein called IFITM might explain why some people shrug off influenza A(H1N1) while others die. US researchers said that the more IFITM a person has, the better.

Stephen Elledge, lead author of the study, also published in Cell (17 December), said the virus replicates 5–10 times more efficiently in the absence of IFITM.

A collaboration between Canadian and Spanish researchers has found that patients with severe A(H1N1) infections have high levels of interleukin-17, a chemical that helps white blood cells fight infection and disease.

The research, published in the journal Critical Care (24 December), could lead to the development of a drug that blocks interleukin-17 to prevent severe cases of A(H1N1).

People with underlying health problems, such as a weak heart or cancer, need prompt, intensive treatment including antibiotic and antiviral drugs when they catch influenza A(H1N1), according to an autopsy study of 21 people who died from the virus.

The Brazilian research was published in the American Journal of Respiratory and Critical Care Medicine this month (1 January).

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