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 Date: March 6, 2002

Contacts: Vanee Vines, Media Relations Officer
Chris Dobbins, Media Relations Assistant
(202) 334-2138; e-mail <news@nas.edu>

ANTHRAX VACCINE IS USEFUL,
BUT SHORTCOMINGS UNDERSCORE NEED FOR REPLACEMENT

WASHINGTON -- The current anthrax vaccine is safe and effective, but certain drawbacks - including reliance on older vaccine technology and a six-dose vaccination schedule over 18 months - underscore the need for a better vaccine, says a new report from the National Academies' Institute of Medicine. The current vaccine can continue to be used, but the U.S. Department of Defense should vigorously support research efforts not only to improve the way it is administered, but also to develop an alternative.

The committee that wrote the report did not identify any unexpected short-term adverse reactions to the anthrax vaccine. Furthermore, the rates at which reactions occurred were similar to rates for other vaccines now in use for adults. Scientific data are limited on adverse health effects that might surface months or years following anthrax inoculations, but the evidence available to date does not confirm any long-term health risks among people who have received the vaccine. Because no vaccine is 100 percent safe, however, DOD should create systems to enhance long-term monitoring of health conditions that might be associated with any vaccine given to military personnel.

"The anthrax vaccine should protect against even the inhalational form of the infection, but the lengthy vaccination schedule and the way the shots are physically administered make it far from optimal; it also is manufactured using older technologies that can be improved upon," said committee chair Brian L. Strom, professor of biostatistics and epidemiology, medicine, and pharmacology; and director, Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania School of Medicine, Philadelphia. "The most prudent course of action is to develop a new vaccine - given the nation's war against terrorism and the domestic attacks where anthrax was used as a deadly weapon. In the meantime, the current vaccine is sufficiently safe and effective to be useful."

The committee pointed out that natural mutations or bioengineered alterations in the anthrax bacteria would not likely produce vaccine-resistant strains. The vaccine acts directly on a toxin from the bacteria, and that toxin must remain unaltered for the bacteria to retain its lethal nature.

ANTHRAX BECOMES A NATIONAL CONCERN

Anthrax primarily is a disease of wild and domestic animals. Historically, humans have contracted it through contact with infected animals or animal products, such as hides contaminated with anthrax spores. Infection occurs when these spores enter the body through inhalation, contact with skin, or ingestion of contaminated meat. However, inhalational anthrax infection had been rare in the United States until the 2001 bioterrorist incidents. Among the people who came in contact with anthrax spores last year, 18 developed confirmed skin or lung infections, leading to five deaths.

Only one anthrax vaccine, referred to as "anthrax vaccine adsorbed" or AVA, is licensed for human use in the United States. At this point, its sole manufacturer is BioPort Corp. in Lansing, Mich. The U.S. Food and Drug Administration approved the vaccine in 1970, largely to protect veterinarians, workers who process animal hair, and scientists working with anthrax. In response to heightened concerns about biological warfare threats during and after the Persian Gulf War, DOD announced in 1997 a plan to vaccinate all U.S. service members to protect them against possible exposure to anthrax bioweapons.

Roughly 2 million doses of the vaccine have been administered, mostly to U.S. military personnel. But some service members have raised concerns about the vaccine's safety and efficacy, and more than 400 military personnel have refused the shots, worried that vaccination could be connected to complaints of chronic fatigue, memory loss, and other health problems. These concerns prompted Congress to request a National Academies study of the vaccine's adverse reactions; long-term health implications; gender differences in reactions; and effectiveness against inhalation exposure.

The report also addresses shortcomings of the manufacturing process and identifies gaps in existing research. It does not examine the military's policy to vaccinate all service members, or consider other populations that could be vaccinated.

A LOOK AT ANTHRAX VACCINE SAFETY

On the whole, the types of reactions associated with the current vaccine and the rates at which they have been observed are comparable to those seen with other vaccines administered to adults, such as the tetanus shot, the report says. Reactions such as skin redness and swelling at the site of the injection are common. Systemic responses - malaise and muscle pain, for example - occur much less often. Reactions may result in time lost from work or brief periods of limited activity, but they do not lead to serious or permanent health impairments. However, women have been more likely than men to experience and report some effects, including swelling and itching at the injection site.

Side effects of the anthrax vaccine, coupled with the required long series of doses, are among the realities that underscore the need for a new and improved alternative, the committee emphasized. Some of the bodily reactions likely stem from the vaccine being injected under the skin rather than into a muscle - which is the typical injection procedure for most vaccines. The anthrax vaccine is given in six shots over 18 months, and an annual booster dose is required. DOD should expedite its research on the anthrax bacteria and disease, and on ways to improve on the current vaccine. A new and improved vaccine should not cause any severe reactions. And among other characteristics, it should require only two or three injections; provide immunity within 30 days that lasts for at least a year; and remain potent for a long period of time so that it can be stockpiled to ensure ample supplies when needed.

The committee evaluated population studies as well as case reports about the safety of the anthrax vaccine. It also heard testimony from those who believe that they or their family members have been harmed by the vaccine. The studies available did not examine vaccination effects in children or the elderly. Although a study is now under way regarding pregnancy outcomes following use of the anthrax vaccine, only limited information exists in this area. The military prohibits giving the vaccine to a woman who knows she is pregnant.

BioPort recently received FDA approval to distribute newly produced anthrax vaccine for the military. Until then, vaccine lots manufactured in the company's renovated facility and filled at another site had not been released pending government approval of plant renovations and satisfactory documentation of the production process. As with all vaccines, government authorities should continue to monitor the company's new batches of anthrax vaccine, the report says.

BROADER RESEARCH EFFORTS NEEDED

More studies using animals are essential for further investigation of the current vaccine's effectiveness and to evaluate any new anthrax vaccines, the committee said. Human studies would not be feasible or responsible.

DOD also should support additional research with laboratory animals on the effectiveness of combining the current anthrax vaccine with antibiotics following inhalation exposure to anthrax spores. These studies should focus on establishing an appropriate time frame for supplemental antibiotic treatment. Limited scientific data now suggest that the vaccine in combination with a 30-day treatment of antibiotics could provide post-exposure protection against inhalational anthrax.

In addition, the report urges the agency to shift its efforts and resources away from specialized programs that review individual reports about adverse events following anthrax inoculations. Instead, the emphasis should be on a broader program for regular analysis of data from the Defense Medical Surveillance System to monitor potential health effects of any vaccine - including the one for anthrax - administered to military personnel. Because these data may point to possible areas of concern and frequently are useful for follow-up analyses of information from civilian reporting systems, DOD also should explore ways to make this information available to civilian researchers.

The study was sponsored by the U.S. Department of Defense. The Institute of Medicine is a private, nonprofit institution that provides health policy advice under a congressional charter granted to the National Academy of Sciences. A committee roster follows.


Read the full text of The Anthrax Vaccine: Is It Safe? Does It Work? for free on the web. Printed copies are available for purchase from the National Academy Press Web site or by calling (202) 334-3313 or 1-800-624-6242. Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).


INSTITUTE OF MEDICINE
Medical Follow-Up Agency

COMMITTEE TO ASSESS THE SAFETY AND EFFICACY OF THE ANTHRAX VACCINE


BRIAN L. STROM, M.D., M.P.H.1 (CHAIR)
Professor of Biostatistics and Epidemiology, Medicine, and Pharmacology;
Director, Center for Clinical Epidemiology and Biostatistics; and
Chair of the Graduate Group in Epidemiology and Biostatistics
School of Medicine
University of Pennsylvania
Philadelphia

WILLIAM E. BARLOW, PH.D.
Senior Scientific Investigator
Center for Health Studies
Group Health Cooperative, and
Research Professor of Biostatistics
University of Washington
Seattle

DAN G. BLAZER II, M.D., M.P.H., PH.D. 1
J.P. Gibbons Professor of Psychiatry and Behavioral Sciences, and Professor of Community and Family Medicine
School of Medicine
Duke University
Durham, N.C.

LINDA D. COWAN, PH.D.
George Lynn Cross Research Professor
Department of Biostatistics and Epidemiology
University of Oklahoma Health Sciences Center
Oklahoma City

KATHRYN M. EDWARDS, M.D.
Professor of Pediatrics and Associate Director
Division of Pediatric Infectious Diseases
School of Medicine
Vanderbilt University
Nashville, Tenn.

DENISE L. FAUSTMAN, M.D., PH.D
Associate Professor of Medicine
Harvard Medical School, and
Director of Immunobiology
Massachusetts General Hospital
Charlestown

EMIL C. GOTSCHLICH, M.D. 1,2
Vice President for Medical Sciences, R. Gwin Follis-Chevron Professor, and Chair of the Laboratory of Bacterial Pathogenesis and Immunology
Rockefeller University
New York City

DENNIS KASPER, M.D. 1
Executive Dean for Academic Programs, William Ellery Channing Professor of Medicine, and Professor of Microbiology and Molecular Genetics
Harvard Medical School, and
Director, Channing Laboratory and Senior Physician
Brigham and Women's Hospital
Boston

DON P. METZGAR, PH.D.
Scientific Consultant
Straudsberg, Pa.

HUGH H. TILSON, M.D., DR.P.H.
Clinical Professor of Epidemiology and Health Policy, and Senior Adviser to the Dean
School of Public Health
University of North Carolina
Chapel Hill

STAFF

LOIS JOELLENBECK, DR.P.H.
Study Director