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Summer 2003 Vol. 3 No. 2

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CDC clinician removes bifurcated needle from saline solution, demonstrating how to safely and efficiently deliver smallpox vaccine, CDC photo by James Gathany

On Guard Against an Old Menace

IOM Advises First-of-Its-Kind Immunization Effort Against Smallpox

Although it was virtually wiped out decades ago, smallpox once again has become one of the most fearsome microbial menaces, thanks to the worry that terrorist groups could have illicit stocks of the virus. In late 2002, the United States announced the start of a unique, nationwide campaign to immunize teams of health care and public health workers against the disease, so they are prepared to respond to a smallpox attack, should one ever occur.

The Institute of Medicine has played a key advisory role since the inception of the campaign when the Centers for Disease Control and Prevention, the agency responsible for coordinating the vaccination program, asked the IOM to provide expert guidance. Although CDC has carried out numerous vaccination efforts over the years, the agency sought an independent, expert review to help ensure that the program proceeded in the best way possible, given the unusual and potentially unknown challenges presented by this particular campaign. The vaccine -- based on a live, weakened cousin of the smallpox virus -- carries greater risk for adverse reactions than other vaccines. Moreover, it was last administered to members of the public more than 30 years ago when children were the principal recipients and contracting the disease naturally was still a possibility.

CDC clinician Gloria Brynam demonstrates proper smallpox vacccine application on clinician Melanie King, CDC photo by James Gathany

From the beginning, the committee formed to address the task stressed that the safety of individuals volunteering to be immunized should be paramount and that the campaign should proceed with the greatest caution and deliberation given the vaccine's known -- and possibly unknown -- risks. Although CDC was given a mandate to inoculate recipients both as rapidly and as safely as possible, the committee advised the agency and its state and local partners to pause after vaccinating a limited first round of health care and public health workers. The break would enable officials to evaluate data, particularly on any adverse events, and make necessary midcourse changes before offering the vaccine to a wider group of medical, public health, and emergency response personnel. If pausing proved unfeasible, the committee urged CDC and its partners to pursue every opportunity to evaluate the program's safety and progress and make needed changes as the program progressed.

The potential for previously unrecognized risks associated with the vaccine became a reality in March, when word came that a few vaccine recipients had experienced cardiac inflammation and a few others had suffered heart attacks, including three individuals who subsequently died. Although it is unclear whether all the cardiac problems are linked to the vaccine, they reinforced the committee's conviction that devoting time to analyze all adverse events is crucial.

As of mid-May, more than 36,600 individuals had been inoculated against smallpox, a number well below the rough estimates initially calculated to be vaccinated nationwide. Although some see the disparity as evidence that the vaccination program is lagging, the committee pointed out that preparedness to deal with a smallpox outbreak is about more than mere numbers. Just as, or even more important, is how well-coordinated and trained the recipients are and whether an appropriate mix of personnel are vaccinated in each region. CDC has called on each state to determine how many people should be immunized based upon local preparedness goals.

As the immunization program proceeds, the IOM committee will continue to assess its progress and offer insights to CDC, helping the agency's officials navigate through additional challenges that may arise.   -- Christine Stencel

Review of the Centers for Disease Control and Prevention's Smallpox Vaccination Program Implementation -- Letter Reports #1, #2, #3, and #4. Committee on Smallpox Vaccination Program Implementation, Board on Health Promotion and Disease Prevention, Institute of Medicine (2003, 52 pp., 42 pp., and 16 pp.).

The committee is chaired by Brian Strom, professor of biostatistics and epidemiology, and of medicine and pharmacology, University of Pennsylvania School of Medicine, Philadelphia. The project is funded by the U.S. Centers for Disease Control and Prevention.

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Copyright 2003 by the National Academy of Sciences