By Marie McCullough
The federal government has
developed a human vaccine
against the H5N1 bird flu, but
it is only moderately effective,
hard to make, and probably not
protective against emerging
strains of the fearsome virus.
The new vaccine, produced by
Sanofi Pasteur in Swiftwater,
Pa., under a $150 million
government contract, is "a small
step" toward being prepared for
a possible global flu epidemic,
said Anthony S. Fauci, director
of the National Institute of
Allergy and Infectious Diseases,
which funded the vaccine
research.
A study of the vaccine
published in today's New England
Journal of Medicine found that
it stimulated a meaningful
immune response only about half
the time -- and only in healthy
adults given two high doses over
28 days. In contrast, a single
low-dose seasonal flu shot is 75
percent to 90 percent effective.
This low potency, coupled
with the fact the vaccine is
grown
in
chcken
eggs -- the same problematic
technology used to make seasonal
flu vaccine -- means that barely
1 percent of the world's
population could be immunized
even if worldwide production
were ramped up.
"This isn't going to be
the vaccine that's going to
protect us," said Gregory A.
Poland, a Mayo Clinic infectious
disease and vaccine researcher
who wrote an editorial that
accompanies the study.
Despite the vaccine's
limitations, U.S. health
officials are going ahead with
plans to stockpile enough to
immunize about 4 million people,
Fauci said during a news
conference this week.
That would cover
high-priority groups -- notably
health care providers and
vaccine plant workers -- and
provide "a very tenuous stopgap"
if a pandemic hits soon, Fauci
said.
The H5N1 virus has
decimated bird flocks in Central
Asia, Eastern Europe and Africa
over the past year. So far, it
has not mutated into a flu that
can spread easily from person to
person, even though almost a
decade has passed since it first
jumped from chickens and killed
seven people in Hong Kong.
If the virus becomes
contagious among people, experts
say the impact would be
calamitous. Humans have no
natural immunity against H5N1 --
of the 176 confirmed human cases
in seven countries, more than
half have died -- and the
ever-changing virus has shown
resistance to anti-viral drugs.
Scientists are racing to
create vaccines, and at least 30
promising drugs are in the
pipeline, including some that
would make cumbersome egg-based
production obsolete.
But the race involves many
obstacles and controversies, as
the new vaccine shows.
Source: Buffalo News
