The US Food and Drug Administration has approved four vaccines against the H1N1 influenza virus will be distributed after the initial lots become available, which is expected within the next four weeks.
The vaccines given the green light are made by CSL of Australia, AstraZeneca’s MedImmune unit, Novartis and Sanofi Pasteur. All four treatments are manufactured “using the same processes, which have a long record of producing safe seasonal influenza vaccines”, the agency noted.

Based on preliminary data from adults participating in multiple clinical studies, the four H1N1 vaccines “induce a robust immune response in most healthy adults eight to 10 days after a single dose”, said the FDA. Studies are under way which will provide additional information about the optimal dose in children, though Sanofi noted that its swine flu vaccine is the only one licensed in the USA for those aged six months of age or older.

US Health Secretary Kathleen Sebelius noted that the government has purchased 195 million doses of swine flu vaccine and will make it available free of charge starting next month, A fifth vaccine, from GlaxoSmithKline, is also expected to be approved shortly, she added.