ZURICH/BEIJING Novartis AG said on Thursday a single dose of its swine flu vaccine might protect against the virus, raising hopes that potentially tight supplies could go further when mass immunization starts this month.
Novartis said a single dose of the Celtura H1N1 vaccine, boosted with an immune-stimulating compound called an adjuvant, produced desired effects in 80 out of 100 volunteers.
The new H1N1 strain of flu, declared a pandemic on June 11, could eventually infect 2 billion people, according to World Health Organization (WHO) estimates.
Because it is a new strain, infectious disease experts have said people will need two doses to get full immunity against the virus. They are rushing vaccine programs as the weather cools in the Northern Hemisphere and the traditional flu season starts.
Chinese health authorities have given a green light to Sinovac, which says its vaccine needs only one shot to be effective.
"This is good news as one dose of Celtura may be sufficient to protect adults against the swine flu. This potentially boosts that availability of flu vaccines for the upcoming flu season when a large outbreak of swing flu is expected," said Karl-Heinz Koch, an analyst at Swiss brokerage Helvea.
But health officials are cautious.
"While we do not yet have full details, these appear to be encouraging results. Any vaccine which can be administered in one dose only will substantially increase the number of overall doses available to the world's people," said WHO spokesman Gregory Hartl.
Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, noted that the Novartis vaccine uses the MF59 adjuvant, while the United States will only use vaccines without an adjuvant.
Cell-based vaccines like Novartis's are quicker and easier to manufacture than traditional flu vaccines grown in chicken eggs. However, supplies are limited for now and currently make up about 30 percent of the Swiss group's capacity.
Novartis said a pilot trial of Celtura run by Britain's Leicester University with 100 volunteers showed a potentially protective immune response in 80 percent of patients after one dose and more than 90 percent after two doses. Other studies with 6,000 adults and children are continuing.
Sinovac, the first company to complete clinical trials, received approval from Chinese health authorities to mass produce a vaccine for the new strain of H1N1 and raised its annual sales forecast.
Some experts remain skeptical, as Sinovac has not published data to back up its claims.
"We look forward to seeing the data from China and elsewhere about vaccine efficacy," Frieden told reporters.
Sinovac shares rose some 16 percent to $9.90 by 1351 GMT, while Novartis slipped 0.8 percent to 48.62 Swiss francs, in line with the DJ Stoxx European healthcare sector.
Other pharmaceutical companies like Sanofi Aventis, GlaxoSmithKline and AstraZeneca's MedImmune unit are also racing to develop H1N1 vaccine as governments scramble to secure supplies.
Clinical trials to see what kind of dose will be needed are under way in the United States, Australia and Europe.
Australia's CSL is already producing H1N1 vaccine and is making 1.0 million to 1.5 million doses per week until it fills all orders.
There is also high demand for antiviral drugs Relenza, from Glaxo, and Tamiflu, made by Switzerland's Roche, which treat flu rather than immunizing against it.
Sales to governments will provide a revenue and profit windfall for many drugmakers this year and in 2010.
"At the beginning of this year, we forecast our sales would rise by 20 percent," Sinovac Chief Executive Yin Weidong said on Thursday. "Looking at things now, H1N1 has given us an opportunity, so the rise should be more than 20 percent."
H1N1 vaccines would be given separately from regular seasonal flu shots.
(Reporting by Sam Cage and Lucy Hornby; Additional reporting by Emma Thomasson in Zurich, Stephanie Nebehay in Geneva and Ben Hirschler in London and Michael Perry in Sydney; Editing by Maggie Fox, Toni Reinhold)