July 22 (Bloomberg) -- The swine flu shot that GlaxoSmithKline Plc is developing will be tested on a limited number of people as the U.K. drugmaker weighs the pandemic’s danger against the risks of an unsafe shot.

“The total population studied in clinical trials will be limited due to the need to provide the vaccine to governments as quickly as possible,” the London-based company said in a statement today. “Additional studies will therefore be required and conducted after the vaccine is made available.”

That may be risky, said Hugh Pennington, a retired microbiologist and emeritus professor of bacteriology at the University of Aberdeen, Scotland. By limiting clinical trials, Glaxo raises the danger that the vaccine dose isn’t properly calibrated, and could lead to shots that don’t protect people from the virus or at worse are unsafe, he said.

“I don’t see any reason why you should fast-track it to perhaps raise public concern about the safety of the vaccine,” he said. The shot’s ability to trigger the body’s defenses is crucial and requires tests to determine the best dose and whether an adjuvant is needed to bolster immunity, he said.

Adjuvants are designed to boost a patient’s immune response to make the vaccine more effective. Regulators, health officials and drugmakers should bear in mind “what happened in the U.S. in 1976,” according to Pennington.

Fort Dix

In 1976, 13 soldiers in training at Fort Dix, New Jersey, fell ill from swine flu and one died, prompting concern that a pandemic would erupt. The disease didn’t spread, but a vaccine developed to prevent it was given to 45 million Americans in 10 weeks. The shot was later linked with a paralyzing neurologic condition that affected more than 1,000 people.

Glaxo in the end may decide to do more tests than currently envisioned, Pennington said.

The swine flu that emerged in April in North America has spread as far as New Zealand and Norway. The disease has killed more than 700 people globally and sickened at least 125,000, taking root across the globe faster than any previous flu, to the World Health Organization said this week.

U.K. Health Secretary Andy Burnham said on July 20 a vaccine against the virus, a new strain that’s evolved in pigs, humans and birds, would be ready at the end of August, and the process of administering doses will begin at the beginning of September. The U.K. has ordered flu shots from Glaxo and Baxter International Inc.

“The sense of urgency is obviously driven by governments who put themselves in a position where they have a need for preparedness,” Glaxo Chief Executive Officer Andrew Witty told reporters on a conference call. “The volume of orders is unprecedented.”

Face Masks

Sanofi-Aventis SA, the French drugmaker developing its own swine flu shot, will begin testing the product in early August.

Paris-based Sanofi estimates it will need as much as two and a half months of tests before having a shot that’s “both safe and protective,” according to Albert Garcia, a spokesman for the company’s vaccine unit. The vaccine will probably be ready in November or December, Garcia said yesterday.

Baxter will produce a vaccine by early August, after which it will perform clinical tests, said Chris Bona, a spokesman for the Deerfield, Illinois, company.

France, which has ordered vaccines from Sanofi, Glaxo and Novartis AG, sees no reason at this point to ask vaccine makers to shorten or skip clinical trials, Health Minister Roselyne Bachelot-Narquin said at a news conference.

‘Necessary’ Approval

“We want the vaccine the soonest possible but we don’t want a product that isn’t of quality,” she said. “We want the vaccines to obtain the necessary regulatory approval” and have “all the necessary guarantee before giving the vaccines to the public.” France should begin receiving vaccine in October, she said.

Glaxo, meanwhile, said it’s on track to meet government orders for 195 million doses of vaccine and another 50 million- dose donation to the World Health Organization and the first supplies should be available in September.

Both Glaxo and Sanofi said they will be tailoring their tests to meet regulators’ demands. “We’re following a playbook which is defined by health authorities,” Witty said.

Glaxo also said today it’s developing a face mask coated with antivirals to prevent infection and boosting production of its Relenza drug for patients already suffering from swine flu.

To contact the reporter on this story: Jason Gale in Singapore at j.gale@bloomberg.netTrista Kelley in London at tkelley2@bloomberg.net

Last Updated: July 22, 2009 11:24 EDT