Posted on 06/30/2002 12:01:38 PM PDT by Paleo Conservative
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Source: Science 296 (5573), May 31, 2002, p. 1594. BIOTERRORISM: In Search of a Kinder, Gentler Vaccine by Martin Enserink James Koopman saw the last 16 cases of smallpox in the Indian district of Azhagar in the early 1970s, but by now they blur together. Crystal clear, however, is the memory of a child, about 1 year old, who suffered from an uncontrollable infection called progressive vaccinia after receiving a smallpox vaccination in 1973. "It completely destroyed her arm, right down to the bone," says Koopman, now a researcher at the University of Michigan, Ann Arbor. To Koopman, that girl is a grim reminder that the traditional smallpox vaccine, a virus called vaccinia that's harvested from the pustules on the skin of infected calves, is very effective -- and also quite dangerous. So current talk of vaccinating thousands or millions makes him rather nervous. But it's not yet clear what the alternatives are. Vaccinia -- known in the United States as a Wyeth product called Dryvax -- works by producing a local infection on the arm, a so-called take, which normally heals in 2 to 3 weeks. But in progressive vaccinia, it grows out of control. Other serious side effects include eczema vaccinatum, a localized or systemic infection in people with a history of eczema, and encephalitis, a brain inflammation. During the smallpox eradication era, about 1250 in every million vaccinees -- many of them children under 2 years of age--suffered one of these side effects, and about one in a million died. Researchers expect that those numbers would be significantly higher today, as millions of people have compromised immune systems as a result of HIV or immunosuppressive drugs. Eczema rates have also shot up, for unknown reasons. A huge new batch of vaccine scheduled for delivery to the government before the end of the year is not expected to be much safer. Produced by a company called Acambis and its subcontractor Baxter, the vaccine is a single, clonal strain of vaccinia, rather than the melange in Dryvax, and it's produced by cleaner techniques. But it was chosen to resemble the old vaccine as closely as possible, says Thomas Monath, chief scientific officer at Acambis, because that's known to work. Animal tests suggest that the new version has a slightly lower risk of causing encephalitis, but other side effects will probably be the same, Monath says. Clinical trials are under way. The National Institutes of Health is pushing both academic and commercial researchers to develop a safer alternative. Such a vaccine could be used in the more than 20% of Americans who either belong to one of various risk groups or are in close contact with those in them -- and perhaps in the long run, the general population. Prime candidates are vaccinia strains that are much more weakened, so that they're powerless to set up an infection but still elicit an immune response. Such highly attenuated vaccinia viruses are already used as backbones for several other vaccines. Aventis Pasteur, for instance, is developing an HIV vaccine based on a highly weakened vaccinia strain called NYVAC; now, it plans to test whether NYVAC by itself might make a smallpox vaccine. But the candidate with the best prospects, experts say -- simply because it has the longest track record -- is a vaccine called modified vaccinia Ankara (MVA). Produced by passaging vaccinia 574 times in chicken embryo fibroblasts, MVA was given to more than 150,000 Germans in the 1970s, most of them at high risk of side effects. The vaccine was used as a primer to establish a baseline immunity, thus preparing the body for the traditional smallpox shot given several months later. MVA was shown to be safe, and it helped people tolerate the real vaccine. One of the two companies developing it, Copenhagen-based Bavarian Nordic, has recently given its version of MVA to small groups of healthy and immunocompromised volunteers; they, too, didn't suffer serious side effects, the company recently reported. But does the combination of MVA and a traditional vaccine work? Unlike Dryvax and other old-style vaccines, it has not proven its mettle in endemic areas, and there was no smallpox around in Germany when it was used. It doesn't produce the telltale take -- and the subsequent scar -- that researchers have always relied on to indicate protection. Because it's unethical to do tests in which human vaccinees are exposed to smallpox, the Food and Drug Administration will have to rely on animal tests, as well as measurements of the immune response it generates in humans. Researchers at the Centers for Disease Control and Prevention and the U.S. Army Medical Research Institute of Infectious Diseases have developed a monkey model of smallpox, which they hope to perfect this year; MVA is one of the first products they plan to test. Because MVA protects against several other members of the orthopoxvirus family, Bavarian Nordic president Peter Wulff is confident that it will pass those remaining tests. He predicts that the combination will eventually replace Dryvax and other traditional vaccines -- not just for high-risk groups but for the general population as well. The objection that it doesn't produce a take, Wulff adds, "is a little beside the point from a scientific viewpoint. What counts is the immune response." But others are not so sure. Donald A. Henderson, former head of the World Health Organization's eradication effort and now a top bioterrorism adviser to the Department of Health and Human Services, for instance, says he'd be leery of relying on anything less than the tried and true to protect the population. "I don't know how you could ever be completely sure of [MVA's] efficacy," Henderson says. The dilemma seems certain to crop up more frequently as scientists shore up the world's defenses against bioterrorist threats. Most of the diseases that would appeal to terrorists are extremely rare in nature, so doing efficacy tests of new drugs and vaccines in humans will usually be impossible -- unless, of course, the worst scenario materializes. |
According to the CDC, the new vaccine produced by Acambis will be produced in a human cell line derived from lung tissue. Reread the article that I posted, it says that the old Drvax vaccine was grown in calves.
There are other groups who are at risk from serious reactions to the current Vaccinia inoculation. Its good that efforts are under way to develop a safer vaccine for those people. However, for the rest of the population, even though the current vaccine is not perfect its still better than contracting weapons grade Smallpox.
I think we should start revaccinating the military immediately. Could this regimnen be tested new recruits?
If Al Qaeda does not have smallpox, existing stocks should be destroyed and no one should be vaccinated.
If there is a real threat, everyone should be immunized immediately with existing vaccine.
I believe it would be better to use the old Vaccinia inoculation on people who have no contraindications. The vaccination method you outline, although it would be safer, would take much longer to confer immunity on the vaccinee. Also it would require twice as much effort to complete and so would not be as easy to use in a mass vaccination campaign.
I think we should start revaccinating the military immediately. Could this regimnen be tested new recruits?
I suppose it could. But personally I would stick with the tried and tested Vaccinia inoculation unless its contraindicated. The military would require prompt protection, this would also be preferable for civilians, the old vaccine gives protection quickest.
The small pox immunization is one of the oldest and most tested vaccines in the history of medicine! It's like asking for the design of Edison's light bulb to be re-engineered.
CDC needs to sit down and get out of the way.
The White House needs to order the release of stockpiles for purchase by pharmacists and physicians!
No gov't agency should be limiting the marketing and sales of a known, medically useful vaccine. CDC and ACIP need to be redirected to only a commenting board. Their power to specific prevent distribution of vaccines needs to be eliminated!
If doctors want to offer the vaccine, if the manufacturer wants to sell it, and if the public wants to BUY it and PAY FOR IT; who the hell is the CDC's ACIP committee to STOP us?
That's what's happening right now. The gov't is specifically blocking the free market.
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