Can U.S. stretch smallpox vaccine stockpile?
October 14, 2001 Posted: 10:44 AM EDT (1444 GMT)
BETHESDA, Maryland -- Researchers are beginning a large new study to see
if they can dilute the nation's small stockpile of smallpox vaccine to make it
stretch farther in case of a bioterrorist attack.
Fresh batches of vaccine are on order, but experts hope that adding more liquid to
the existing supply will be a temporary solution at least until those begin to arrive
next summer. The need for protection against the disease, which has been
eradicated in its natural form, has become more pressing since the September 11
terrorist attacks. There is no treatment for smallpox, and routine vaccinations
ceased in the United States in 1972 because it was no longer considered a threat.
Most people vaccinated before then have lost their resistance to the virus. Some
experts fear that smallpox manufactured by the Soviet Union in the 1980s for
biowarfare may have been obtained by rogue nations and could be used in
bioterrorist attacks.
The government has 15.4 million doses of smallpox vaccine stockpiled at secret
warehouses around the country. Researchers at four institutions will test whether
the vaccine can be diluted to one-fifth and one-tenth of their standard dosage and
still prevent infection.
"It's a very quick way to markedly expand the amount of vaccine that we already
have, which on face value in the undiluted form would not be a lot. It's prudent to
be prepared," said Dr. Anthony S. Fauci, head of the National Institute of Allergy
and Infectious Disease, which is funding the experiment.
If the approach works, Fauci said the diluted vaccine could be ready by the end of
this year.
However, diluting the vaccine is not meant to be an alternative to the new doses in
production, said Dr. Sharon Frey, the lead researcher on the smallpox study at St.
Louis University. "This is a stopgap measure to make more doses available until that
new vaccine is developed."
Over a 2 1/2-month period beginning next month, researchers at St. Louis, the
University of Maryland, the University of Rochester and Baylor College of Medicine
will study 684 adults under the age of 32 who have never been vaccinated for
smallpox. They will see if the diluted vaccines trigger production of protective
antibodies and create a telltale scab.
In a pilot study last year on 20 people, researchers used vaccines diluted by 10
times and by 100 times. The one-tenth doses produced a significant number of
positive results, while the doses that were 100 times weaker had little effect.
Anything that would increase the country's limited stockpile is an improvement,
said Dr. Neal Halsey, who studies vaccines at the Johns Hopkins University.
"I am sure there is nowhere near enough smallpox vaccine to provide it to everyone
in the country and even those who would be exposed in a large incident," he said.
Smallpox is a viral disease that causes high fevers, rashes and sores that cover the
whole body. The disease is fatal in about a third of all cases.
While inhaled anthrax is much more lethal, killing roughly 90 percent of all patients,
it isn't contagious. Smallpox released in a bioterror attack, however, could spread
rapidly throughout a population and infect thousands because it is passed through
the air. cnn.com |
