HEALTH & SCIENCE

Risk-benefit ratio steers public health action

Weighing the factors in whether to recommend the anthrax vaccine highlights the challenges facing the public health community.

By Stephanie Stapleton, AMNews staff. Jan. 14, 2002. Additional information

Washington -- Last month, when Health and Human Services Secretary Tommy Thompson issued a set of additional treatment options for people exposed to anthrax, his action underscored how the public health system is struggling to meet the challenge of protecting citizens against a range of biological threats.

The new treatment options Thompson outlined were generated by the unusual set of circumstances with which public health and medical experts now must contend. The approach demonstrates how interventions are being developed based on an evolving body of experience and knowledge.

Meanwhile, the issues involved are complex. They touch on how public health agencies plan emergency responses, provide vaccines and other treatments, and hold the public's trust. A central variable is how experts communicate to the public the risks at stake -- from exposure and illness as well as from vaccines and treatments. At the heart of the debate, then, is a discussion that touches on questions that play into immunization in general, and now, specific vaccinations against threats such as anthrax and smallpox.

"The whole subject of protection has clearly been in the public arena," said Michael J. Scotti, MD, AMA senior vice president for professional standards and a retired general from the Army Medical Corps.

On Dec. 18, 2001, Thompson outlined two supplemental preventive treatments for people -- mainly postal workers -- exposed to anthrax spores. Since October 2001, when two anthrax-contaminated letters were identified, about 10,000 people have been on preventive 60-day antibiotics regimens.

According to HHS, those who were prescribed this antibiotic course and who conclude this course of treatment, or who stopped taking the medicine early, should remain watchful of their health and be in close communication with a physician.

To date, no new cases have been reported from among these exposures. But some animal studies have detected live spores in the lungs up to 100 days after exposure, even though the animals did not develop disease. This finding raises the possibility that the spores remaining in the lungs might still, after 60 days, cause anthrax.

Therefore, HHS will make available 40 additional days of antibiotic therapy to those who choose it. HHS also will offer the anthrax vaccine on an experimental basis. Health officials are suggesting that about 3,000 people -- those who have had significant exposure to anthrax -- strongly consider taking advantage of these options, said Centers for Disease Control and Prevention spokeswoman Kathy Harben.

The vaccine will be given under an investigational new drug application in recognition of the limited knowledge about both the development and treatment of inhalation anthrax. "We're learning as we go along," she said. "The CDC did not want to mandate that people take the vaccine."

In this postexposure, experimental use, a person's full informed consent would be required and the vaccine would be given in three doses over four weeks to provide immunity to infection over a longer time. The step comes with some degree of controversy.

The vaccine is not new. It has long been given to people at occupational risk of exposure -- certain types of veterinarians, livestock handlers, laboratory workers exposed to anthrax bacteria and selected military personnel.

But many experts consider antibiotic therapy to be sufficient. There is also concern about the vaccine's side effects -- the subject of multiple Capitol Hill hearings on the military's vaccination effort. In addition, the vaccine maker, BioPort, has faced manufacturing difficulties and Food and Drug Administration scrutiny.

Still, the anthrax vaccine decision is an example of how caculating risks and benefits guides public health response. "The risk side of the equation has changed dramatically," said AMA Trustee Ronald Davis, MD. "We've seen bioterrorism in this country."

But at press time, few postal workers had opted for extra protection. Their reasons include the fact that the CDC did not directly recommend it.

"We understand that there is frustration, but a stronger recommendation couldn't be made," said the CDC's Harben. "We wish we would have had more information. There was not enough for a strong recommendation. But there was enough of a sense of benefit that it would not have been appropriate not to make the vaccine available. The CDC is very comfortable with the way the counseling is going."

In New York, about 400 postal workers were counseled on risks and options on the first day of vaccine availability. Of this group, eight opted for the extra 40-day course of antibiotics. No one chose the vaccine. In Washington, 72 people were counseled, 65 chose to take more antibiotics, and seven of these also opted for the vaccine.

Understanding risks, benefits

But the discussion about the smallpox vaccine is different. There is a significant body of data regarding both the illness and the vaccine. For now, the general public seems to have an understanding that, while smallpox has been eradicated, the vaccine used has risks, said Bruce Gellin, MD, MPH, an assistant professor in Vanderbilt University's Dept. of Preventive Medicine and deputy director of the National Network of Immunization Information. This reality is pitted against concerns that the disease could be used in a terrorist assault.

The vaccine, not routinely administered since 1972, "does have risks -- a risk of death," noted the AMA's Dr. Davis. Statistics put that risk at about one in a million doses. "We have to balance that cost against the potential risk of not vaccinating," he added.

This calculation includes the ability to contain smallpox using CDC's strategy -- the ring vaccination approach, which involves vaccinating the contacts of any reported case. And vaccination within four days of a first exposure offers some protection against infection and significant protection against a fatal illness, according to an NNII fact sheet.

Still, the AMA House of Delegates asked the AMA Board of Trustees during the Interim Meeting last month to study the complexities involved.

Meanwhile, some experts are now speculating as to whether the focus on anthrax and smallpox vaccines could have a positive impact on other prevention issues.

The bioterrorist threat could "bring some reality to the nation's discussion about immunization," said William Roper, MD, MPH, dean of the School of Public Health at the University of North Carolina at Chapel Hill.

Anecdotal evidence suggests that there was more interest than usual in the flu shot this year, triggered by publicity from then-New York City Mayor Rudy Giuliani. In some ways the flu vaccine offered a mechanism to minimize fears about anthrax. The idea was that by lessening the chance of the flu, people would exhibit fewer flu-like symptoms and, in turn, would not be as unnecessarily scared of anthrax.

"People were trying to do something where they could be in control," speculated Dr. Gellin. But whether that behavior spills over to next year's behavior is yet to be seen.

One of the most interesting findings so far comes from a recent survey by the Harvard School of Public Health, he said. According to the survey, "three-fourths of the public has a great deal or quite a lot of trust in their own doctor, which speaks to the importance of educating physicians about bioterrorist threats."

"What is important, then, is what the doctors actually know about these things," Dr. Gellin said.

Public Health: Renewed Attention is a six-part series exploring the role of the public health system in the context of our nation's heightened state of alert. The next article will focus on public health system changes that might come with more resources.

Anthrax: supplemental treatments

Current recommendation: 60 days of antibiotics, accompanied by careful monitoring.

Option 1: 40 additional days of antibiotics to protect against the theoretical possibility that spores might cause infection up to 100 days after exposure. Accompanied by monitoring by physician.

Option 2: 40 additional days of antibiotics, plus three doses of anthrax vaccine administered over four weeks. Because this is not an FDA-approved use of the vaccine, it would require the full informed consent of the individual and a follow-up study measuring the effect of postexposure vaccine.

Source: Dept. of Health and Human Services, Dec. 18, 2001.

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HHS on anthrax (http://www.hhs.gov/hottopics/healing/biological.html)

CDC on anthrax (http://www.bt.cdc.gov/Agent/Anthrax/Anthrax.asp)

CDC on smallpox (http://www.cdc.gov/nip/smallpox/)

AMA on disaster preparedness and medical response (http://www.ama-assn.org/go/disasterpreparedness)

National Network for Immunization (http://www.immunizationinfo.org/)

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Copyright 2002 American Medical Association. All rights reserved.

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Box: Anthrax: supplemental treatments

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