Both sanofi-aventis and Novartis have begun testing their swine flu vaccines in human clinical trials.
Novartis’ vaccine is being tested in a year-long trial of 6,000 people of all ages in Britain, Germany and the United States, though the vaccine is expected to be on the market before the trial finishes.
Sanofi-aventis has begun its studies in 2,000 people in the US.
Australian drug manufacturer CSL became the first vaccine-maker to start testing its vaccine in humans in Australia last month.
The vaccines being tested in Europe use an adjuvant, an ingredient used to boost the body’s immune response. In the US, however, Novartis is only testing vaccines without adjuvants, spokesperson Eric Althoff said.
WHO recommends that countries use vaccines with adjuvants to stretch the global supply of swine flu vaccine. However, there are no licensed flu vaccines with adjuvants in the United States.
Once Novartis has preliminary data from the trial, they plan to submit them to drug regulators including the European Medicines Agency, many of which have a fast-track process for approving swine flu vaccine.
The EMEA has previously said that swine flu vaccines based on a pre-approved bird flu vaccine could be licensed within five days, even without extensive testing in humans.
Althoff said the company expected to start shipping vaccine in the last quarter of 2009, and will continue the deliveries next year.