By Peter Gorner
Tribune science reporter
March
28, 2004
Some scientists are questioning a U.S. government
plan to spend as much as $1.4 billion on an unlicensed, experimental
anthrax vaccine to be stockpiled in case bioterrorists attack
American cities.
Although the vaccine has been tested in
animals, testing in humans is in its early phases and the vaccine has
not yet demonstrated its effectiveness, making the purchasing plan
premature, according to critics.
But the Bush administration,
as a follow-up to its promise to have enough smallpox vaccine on hand
for every American, said it hopes that within two years the country
will have sufficient quantities of the new anthrax vaccine to
inoculate 25 million people.
That, along with the storage of
antibiotics that already have proved their effectiveness against
anthrax spores, could serve as countermeasures against a feared
biological agent.
"As the lead federal agency for public
health and medical response, we are moving forward to ensure our
nation is protected against anthrax," said Tommy G. Thompson,
secretary of the Department of Health and Human Services.
But
an anthrax expert, Dr. Meryl Nass, of Bar Harbor, Maine, cautioned
that the public "should not be misled that this vaccine is an
improvement to the currently licensed vaccine.
"This one
is definitely more pure, but unfortunately its purity has not been
shown to improve safety or effectiveness," said Nass, a former
government consultant who led the campaign against the existing
vaccine after getting reports from military personnel of mystifying
and serious side effects.
After a terrorist attack, the U.S.
plan calls for the entire population of a city to be inoculated with
the new vaccine, while also taking antibiotics until immunity
develops.
After that, with regular booster shots, people
theoretically would be immune to anthrax, even if spores lingered for
years, as they have been shown to do.
Nass said that most
"shocking" is the government's contention that the new
vaccine would enable cities contaminated with anthrax to be
habitable.
`Most bogus thing'
"Where's the science
behind that? It's the biggest, most bogus thing of all," she
said.
The only currently licensed anthrax vaccine in the U.S.
is a mixture of proteins produced by a weakened form of Bacillus
anthracis, the bacterium that causes the deadly disease in animals
and people.
Developed for animal-hide workers in the 1950s and
used primarily by the military, the vaccine requires six injections
over 18 months and has been associated with severe side effects.
The
licensed anthrax vaccine became the subject of bad publicity and
litigation because of the Pentagon's insistence on mandatory
vaccination of troops. The vaccine's reputation never
recovered.
During the anthrax-letters panic of 2001, nearly
all of the postal workers at risk refused the vaccine when it was
offered.
Nonetheless, some skeptics are questioning what they
perceive as the rush by the government to buy several million doses
of the new vaccine, called rPA102, before clinical trials are
completed and its safety and effectiveness evaluated.
Also
being questioned is the choice of the main manufacturer, VaxGen Inc.
of Brisbane, Calif., a company whose AIDS vaccine failed inclinical
trials in 2003.
"Once again, VaxGen has managed to
leverage few scientific data to capture a significant amount of
federal dollars," said Dr. Steven Wolinsky, an AIDS researcher
and chief of the division of infectious diseases at the Feinberg
Medical School at Northwestern University.
"Most of us in
the scientific community agree there is meager scientific evidence to
support this effort. As a clinician, I would not offer the vaccine to
people exposed to anthrax spores without providing them with
concomitant drug treatment."
More promising anthrax
vaccines are in the pipeline, but they may fail to attract commercial
developers because the government already has made up its mind, some
experts contend.
They also warn of another potential anthrax
vaccine boondoggle that would make the legal, medical and ethical
disputes over the existing vaccine, BioThrax, pale by
comparison.
Bidding will close April 16 on a contract for 75
million doses of the rPA102 vaccine that is expected to be awarded to
VaxGen and Avecia Ltd, a privately held company based in Manchester,
England.
According to the Department of Health and Human
Services, "the new vaccine has already shown to be stronger and
more effective than the vaccine being used today. It will require
fewer doses per individual to provide immunity against the effects of
anthrax inhalation."
The firms already have
contracts--VaxGen for $80.3 million and Avecia for $71.3 million--to
each produce 3 million doses and conduct human trials to test the
vaccine.
The new vaccine is a purified protein designed to
stimulate the body to produce antibodies to neutralize the most
dangerous part of anthrax--called protective antigen, or PA.
"The
way anthrax works is that one part attaches to your cell and the
other part [the protective antigen] gets flipped on the inside to
have the toxic effect," said Dr. Craig E. Smith, representing
the Bioterrorism Work Group of the Infectious Diseases Society of
America.
"This vaccine stimulates antibodies that destroy
the attachment component so the toxic part can't get into where it
needs to do its dirty work. It just gets washed out of your system
without any problem," Smith said.
"If a bomb blew up
and the cloud spread anthrax through the city, we could follow the
cloud and vaccinate the 2 million people downstream who may take
weeks to months to manifest the disease."
Smith called
the new vaccine "a no-brainer. A win-win situation."
VaxGen
recently reported that the first phase of human testing--with 100
volunteers age 18 to 49--showed that antibody responses to higher
doses of rPA102 conferred protection within the same range as the
existing vaccine.
Dr. Harry L. Keyserling, professor of
pediatrics at Emory University School of Medicine, conducted the
clinical trial with colleagues from St. Louis University and Baylor
and Johns Hopkins Universities.
Local reactions, mainly arm
pain, were more common with the old vaccine, but short-lived systemic
reactions, mostly headache and fatigue, were more than twice as
common (39 percent versus 18 percent) with the new vaccine.
"Side
effects were mild, nothing that would interfere with everyday
activity. Further studies will continue to monitor reactions and
adverse effects," said VaxGen spokeswoman Kesinee Yip.
But
systemic reactions worry some specialists because long-term effects
of the vaccine are virtually unstudied and initial systemic
reactions--reactions away from the injection site--could put people
at high risk of chronic illness later.
Linked to
problems
Published case reports have linked anthrax vaccine to
a host of problems including chronic fatiguing illnesses, chronic
pain syndromes and endocrine and autoimmune disorders.
Another
top government official insisted the new vaccine purchase plan is not
precipitous and "was all done in a very measured, careful
way.
"There were multiple contracts doing the research to
show that it was safe and stimulated the immune system against
anthrax. Now comes the production capabilities to put it in place,"
said Dr. Anthony S. Fauci, director of the National Institute of
Allergy and Infectious Diseases.
"We now have enough
smallpox vaccine to handle anything. But with anthrax vaccine, we had
a gap," Fauci said.
"We didn't have enough vaccine
if, indeed, we had an attack on a city. Nor did we have enough to
vaccinate first responders and others who might be doing the cleanups
after an attack of anthrax."
As with the current vaccine,
the new vaccine was developed by bioweapons specialists at the U.S.
Army Medical Research Institute of Infectious Diseases at Ft.
Detrick, Md. They successfully tested the vaccine for years in
primates, officials said.
"Almost two years ago, we
started a strategic plan for developing countermeasures to high-risk
agents--smallpox, anthrax, tularemia, plague, botulism toxins and the
hemmorhagic fevers. This purchase is part of that," Fauci
said.
Others challenge that assertion, however.
"The
primary ingredient, PA [protective antigen] has significant toxicity.
Since no immediate need exists, and testing has not been completed,
why rush to order a huge stockpile of such a vaccine?" asked
Nass."VaxGen is only at the Phase 1 stage, pre-efficacy testing.
Why buy a huge amount of a product before the manufacturer has showed
it will work?
"Many things are dropped much later as a
result of Phase 3 testing--like VaxGen's AIDS vaccine. Nothing should
be purchased in bulk at this very early stage of testing," Nass
said.