Glaxo touts bird flu vaccine
Glaxo touts bird flu vaccine
Manufacturers race to develop effective virus inoculation
- Bernadette Tansey, Chronicle Staff Writer
Thursday, July 27, 2006
GlaxoSmithKline said Wednesday that its experimental bird flu vaccine delivered the best results shown so far among the manufacturers who are racing to develop an effective inoculation against the deadly avian virus.
Glaxo said an additive it included in the vaccine boosted its power, allowing the use of significantly lower doses while also producing a higher rate of response than the vaccine candidates of competitors whose data have already been reported.
The lower the dose needed, the more shots a factory can produce. And the world's drug manufacturing plants might need to churn out vaccine quickly, because an avian flu pandemic could rapidly sweep the world population.
The effectiveness of bird flu vaccines is evaluated by measuring by the level of antibodies produced by inoculated human subjects. Scientists predict that a sufficient level of antibodies will activate the immune system to attack the virus if the immunized person is exposed to it. But trial subjects are not exposed to the H5N1 virus, because that would be too dangerous.
The H5N1 strain is primarily a disease of birds that doesn't infect humans easily. But of the 232 cases reported by the World Health Organization, 134 have died. Most are believed to have had close contact with infected birds. The fear among public health officials is that the virus will mutate into a pandemic form transmitted easily from person to person.
Stockpiles of experimental H5N1 vaccines are on order by the United States and other governments. But it's not clear whether any vaccine manufactured in advance, based on H5N1 strains in circulation, will protect against a mutated variety that may eventually cause a pandemic. Glaxo is conducting studies to determine whether its vaccine will deliver cross-protection against different viral strains.
The government has been fostering the study of additives, also called adjuvants, as a strategy for stretching limited supplies of vaccine, said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.
"I'm totally delighted that GlaxoSmithKline has had this advance,'' said Fauci. "It's not the solution to the problem, but you can certainly say it's good news.''
Results had been disappointing for another manufacturer, Sanofi-Aventis. In March, the French company reported that its bird flu vaccine induced a significant immune response in only 50 percent of trial subjects when two doses of 90 micrograms each were injected. With the addition of an adjuvant called alum, the results improved. But not enough, Fauci said. Two doses of 30 micrograms each were required to spur immune responses in 67 percent of subjects.
With Glaxo's proprietary adjuvant, 80 percent of subjects responded when given two shots of 3.8 micrograms each. J.P. Garnier, GlaxoSmithKline's chief executive officer, said no other manufacturer has produced such a strong response at such a low dose of vaccine created from H5N1, the bird flu strain considered a leading contender to cause a pandemic.
"These excellent clinical trial results represent a significant breakthrough in the development of our pandemic flu vaccine,'' said Garnier. Glaxo will seek regulatory approval for the vaccine in the coming months, he said.
Fauci said he predicts similar results will be achieved by Novartis with an H5N1 vaccine developed by a Bay Area company it recently acquired, Chiron Corp. The Novartis vaccine includes an adjuvant similar to Glaxo's, he said.
Sanofi, in a prepared statement, said it will continue to study formulations that include alum, because it is "the world's most widely used and proven adjuvant currently licensed for vaccines. We believe following this initial clinical path with a time-tested adjuvant is a fast way to attain a licensable vaccine with the safest profile possible. Future initiatives will look at alternative adjuvants.''
Glaxo did not give details about the composition of its proprietary adjuvant. The company would consider licensing it to other manufacturers in the event of a bird flu pandemic, said spokeswoman Patti Seif.
Along with its bird flu vaccine news, Glaxo reported a 14 percent increase in second-quarter profit Wednesday. Glaxo shares dropped 87 cents, or 1.53 percent, to close at $56.04.
E-mail Bernadette Tansey at firstname.lastname@example.org.
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