H1N1 Slow growing flu vaccine; Critically Delayed Production

Vaccine producers have hit a snag making vaccine against the swine flu pandemic. According to a report by the World Health Organisation, the fastest-growing of all the vaccine strains tested so far grows only half as fast as ordinary vaccine viruses.

Vaccine companies must fill pandemic vaccine contracts with countries such as Britain, Australia, France and the US before they can start making vaccine for the rest of the world – notably developing countries. Marie-Paul Kieny, the WHO's head of vaccines, told a meeting in Geneva last week (pdf format) that if the pandemic vaccine virus grew as fast as ordinary strains, these contracts could be filled by November 2009.

That date applies only if the vaccine works at half the dose of ordinary vaccines, with one shot enough to induce the required immune reaction. If the usual dose and two shots are needed, the contracts cannot be filled until April 2010.

But the slow-growing virus means these dates could be pushed back to January 2010 and June 2010 respectively. If the current pandemic behaves like the last H1N1 pandemic in 1918, the next, possibly worse waves of infection could be long over by then.