Despite Lacking Latest Virus, Flu Vaccine Is Thought to Work
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November 18, 2003
(Comment: You know what thought did? Thinking and believing is not the same as
nowing. - CW)
By LAWRENCE K. ALTMAN
The influenza vaccine now being given was not developed to protect against a
strain of the virus that has surfaced in this country this fall, but the
government is optimistic that this year's vaccine will stave off outbreaks,
a top federal health official said yesterday.
The reason is that animal studies suggest that the strains of virus included
in the vaccine are close enough to the new one that the vaccine will still
protect, said the official, Dr. Julie L. Gerberding, the director of the
Centers for Disease Control and Prevention in Atlanta.
Still, she warned, the United States could face a severe epidemic this year,
given that the flu season began unusually early and has hit Texas and
Colorado particularly hard.
"It's a little too early to say whether or not this portends the worst flu
season we have had in a long time," Dr. Gerberding said in a telephone news
conference. Her agency is responsible for tracking and controlling influenza
and other infectious diseases.
She said she was "sounding the alarm" to urge more people to get flu shots
to "nip this problem in the bud." The center does not know how many people
have received flu shots this season. "People have the impression we are
doing better this year than last year, but we do not have the data to back
that up at this point in time," she said.
The flu vaccine includes three strains of influenza virus, but was not
designed to protect against a new one that has appeared in a number of
countries over the last year. It is known as the Fujian strain, a variant of
the Panama strain that is included in the current vaccine. Both are
categorized as H3N2 strains that have been linked to higher rates of serious
illness requiring admission to a hospital and to death, Dr. Gerberding said.
Each year, influenza causes 114,000 hospital admissions and 36,000 deaths.
The influenza virus mutates frequently. Health officials change the strains
of virus put in the flu vaccine each year as they try to keep up with
mutations. But matching strains in the vaccine with those circulating among
humans during a flu season is a notoriously unpredictable exercise.
The World Health Organization committee that makes the recommendations for
the flu vaccine knew about the Fujian strain in February, said Dr. Klaus
St�hr, an influenza expert at the organization. But Dr. St�hr said in a
recent interview that the committee decided not to include the Fujian strain
because scientists could not make it pure enough in time for a human
vaccine.
The flu vaccine is prepared in eggs. Decisions about the components of the
vaccine have to be made months in advance in part because manufacturers and
farmers need to know how many eggs to prepare in anticipation of demand.
Influenza typically occurs during the winter in each hemisphere, and the
vaccines are prepared at different times. The vaccine being prepared for use
in the Southern Hemisphere will include the Fujian strain, Dr. St�hr said.
"There may be less than optimal protection against H3N2" in the Northern
Hemisphere, "but no vaccine failure has been reported" there, he said. "So
there is no reason to discourage people from getting vaccinated."
Dr. Gerberding said it was common for the circulating influenza to gradually
change genetically - known as "drift" - as it spreads to infect more people.
Tests at the center found that 84 percent of the 55 strains of influenza
virus isolated this fall are the Fujian strain, Dr. Gerberding said. But she
emphasized that protection could still occur even without a perfect match.
Dr. Gerberding said that an earlier than usual onset of the flu had occurred
in some European countries but that "this is not a pandemic."
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