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  • Swine flu science update: 10 September 2009


A single dose of a swine flu — influenza A(H1N1) — vaccine is enough to provide immunity, a trial has found.

Reuters reported last week (3 September) on a trial of the MF59 adjuvanted cell culture-based vaccine, made by Novartis, on 100 volunteers in the United Kingdom. The drug was well tolerated and elicited a strong immune response.

Trial leader Iain Stephenson, consultant in infectious diseases at Leicester Royal Infirmary, said two doses of the vaccine gave better results but a single dose was protective.

Xinhua reported last week (4 September) that the Chinese government has ordered its first batch of A(H1N1) vaccine. Pharmaceutical companies Sinovac Biotech and Hualan Biological will produce 3.3 million and four million 15 microgram doses respectively.

Roche says it has found a way to extract the active ingredient from expiring stockpiles of the antiviral Tamiflu. Company spokesperson Catherine Steele told The Associated Press this week (8 September) that reprocessing expiring stockpiles of the drug could save developing countries money. She also said the shelf life of Tamiflu has been extended from five to seven years.

Roche researchers report that drug-resistant A(H1N1) is not widespread and appears to develop largely in individuals who have taken half the recommended dose of Tamiflu.

Doctors may have found a new way of treating people resistant to Tamiflu.* An immunocompromised cancer patient with Tamiflu-resistant A(H1N1) recovered after receiving intravenously an unlicensed, liquid form of the antiviral Relenza.

The drug is usually administered by an inhaler but the patient's lungs had too much fluid for the drug to work this way. A case study was published in The Lancet last week (4 September).

Turkeys in Chile have contracted the A(H1N1) virus, Chilean authorities have announced. Birds have apparently been infected by farm workers at two farms near the port of Valparaiso, BBC Online reported last month (27 August).

The development raises the possibility of A(H1N1) genetic material reassorting with another influenza strain in birds to create a more dangerous virus. But scientists say this would be more of a concern in South-East Asia, where there are high rates of H5N1 in poultry.

Chilean authorities will not cull the birds and have quarantined them while they recover.

Reports last month that an Egyptian man was infected with both A(H1N1) and H5N1 bird flu are false, according to the US Centers for Disease Control and Infection. ScienceInsider reported than the man is most likely infected with A(H1N1) and a seasonal strain.

Researchers at the University of Maryland say they are confident that A(H1N1) is not reassorting with seasonal flu viruses in humans to produce a more dangerous strain.

In an article published in PLoS Currents: Influenza last month (25 August) researchers infected ferrets with A(H1N1) and seasonal H1N1 or H3N2 strains. They found that A(H1N1) had a biological advantage over the seasonal strains but there was no evidence of reassortment.

Researchers from Imperial College London have found more evidence for the ability of A(H1N1) to infect cells deep in the lung. They report in Nature Biotechnology today that A(H1N1) can attach to receptors in lung cells, therefore affecting more of the respiratory tract.

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