Lack of sprayers hampers MedImmune's bumper vaccine

*Company can make 200 million doses

*But only 40 million devices on hand to deliver vaccine

*Nose drops possible

By Maggie Fox, Health and Science Editor

GAITHERSBURG, Maryland, July 23 (Reuters) - Some flu vaccine makers are having trouble making large batches of H1N1 swine flu vaccine, but not MedImmune, the company reported on Thursday.

The Maryland-based biotech, now owned by AstraZeneca (AZN.L), can produce about 200 million doses in bulk, Ben Machielse, head of operations, told Reuters in an interview.

But the nasal spray vaccine maker will only be able to deliver about 40 million doses of its product because it lacks the sprayers to squirt the vaccine into the nose, Machielse said.

He said the company was working with the FDA to approve an alternative means of delivery, by dropping the vaccine into the nose. MedImmune also presented this information to a meeting of a U.S. Food and Drug Administration's vaccine advisory committee.

"We have clinical studies ... where you just apply a drop of vaccine in the nose and that works, too," Machielse said.

Earlier this month, the World Health Organization said some of the companies making a vaccine against H1N1 were having trouble growing the virus.

Influenza vaccines are made in a old-fashioned way, by inoculating fertilized chicken eggs with the virus, letting it grow, and then purifying and inactivating the virus to make a vaccine.

Some strains grow better in eggs than others, and this affects how many doses of vaccine a company can manufacture. But Machielse said MedImmune did not have this problem.

"I am pleased to report that we don't have trouble. We have a strain which is producing very good quantities of virus," he said. "We have it five months after the first report of H1N1. That shows this technology could be very useful to be scaled up."

MedImmune and other flu vaccine makers presented their progress to a meeting on Thursday of the FDA's Vaccines and Related Biological Products Advisory Committee.

NEEDLE FREE TECHNOLOGY

Machielse said his company's needle-free technology was particularly well suited for use in schools. The U.S. Centers for Disease Control and Prevention has said states should consider mass vaccination programs in schools if H1N1 continues to circulate, or worsens, in the autumn.

MedImmune believes its vaccine has other advantages. It is made from a live, but weakened, flu virus, unlike others which are completely killed. This prompts a stronger immune response, studies have shown.

The drawbacks are that the inhaled vaccine is not recommended for use by asthma patients, people with compromised immune systems or the very young.

Australia's CSL Ltd (CSL.AX), Baxter International (BAX.N), GlaxoSmithKline Plc (GSK.L), Novartis AG (NOVN.VX) and Sanofi-Aventis SA (SASY.PA) all make H1N1 vaccines.

The U.S. National Institutes of Health reported on Wednesday it had assigned human trials of CSL's and Sanofi's vaccines to start in August at various academic centers and clinics.

Vaccine experts will test different doses of the H1N1 vaccine to see how large a dose people need to be protected, and also deliver it along with the seasonal flu vaccine to see if that will work .

Most flu experts agree that people are likely to need two separate doses of H1N1 vaccine because those born after 1918 have little or no immunity. There is a very distant relative of H1N1 included in the seasonal flu cocktail and it is not known if giving the two together may cause problems.

Machielse said MedImmune's live vaccine, however, may not need two doses. One dose of its seasonal flu vaccine gives between 65 percent and 85 percent protection to children who have never been immunized before -- children who usually need two doses of other flu vaccines to get full protection.

Swine flu is spreading "briskly" in older children and younger adults in the Southern Hemisphere, the U.S. Centers for Disease Control and Prevention's Dr. Anthony Fiore told the FDA meeting earlier on Thursday.

"In past pandemics, influenza viruses have needed more than six months to spread as widely as the new H1N1 virus has spread in less than six weeks," WHO said in a statement last week.

The virus, which officials estimate has infected millions of people, has defied the heat and humidity of the Northern Hemisphere summer, as well. Usually respiratory viruses such as flu do not circulate well in summer months. (Editing by Doina Chiacu)