Drug companies have to race against the clock to make available some swine flu vaccines by mid-September, White House science advisors say.

The President's Council of Advisors on Science and Technology recommended that manufacturers begin packaging bulk vaccines into vials and syringes immediately, so that some of the vaccines could be available in September for those at high-risk.

Calling the H1N1 pandemic 'a serious threat to our nation' the health officials also urged the US Food and Drug Administration (FDA) to quickly decide on new intravenous formulations of flu drugs, including current drugs such as Roche AG's Tamiflu and GlaxoSmithKline's Relenza and also BioCryst Pharmaceuticals' experimental drug Peramivir.

Most experts believe that people will need two doses of the vaccine, delivered at least two weeks apart, to develop full immunity to the new H1N1 flu.

Last week the US Department of Health and Human Services (HHS) said only 45 million doses of the new H1N1 vaccine would be on hand in mid-October, instead of the 120 million previously forecast, with 20 million a week due after that.

HHS plans to eventually vaccinate at least 160 million people by December, with pregnant women, healthcare workers, children and young adults given a higher priority.

FTP/SME/MMN