The United States looks set to widen the group of health workers and other 'first responders' who will be inoculated against smallpox, as a precaution against a possible bioterror attack.
Public-health officials argue that inoculating the larger group could serve as a much-needed clinical trial of a modern, laboratory-produced smallpox vaccine, as well as strengthening the United States' ability to contain a smallpox outbreak.
A committee that advises US health officials on immunization policies may issue new guidelines on smallpox vaccination this week. The Advisory Committee on Immunization Practices (ACIP) was due to meet in Atlanta, Georgia, on 19–20 June and, according to several experts, was likely to recommend a more extensive vaccination programme. But the experts differ on which 'first responder' groups should be vaccinated, with candidates including hospital staff, police officers and emergency-response teams.
The ACIP's present recommendation is that only a small group of health workers who have to handle viruses related to smallpox be vaccinated. But many observers say that the committee is set to change its advice after consultation with scientists, including a public discussion organized on 15 June in Washington by the Institute of Medicine.
“It appears to me from town-hall-type meetings, as well as the tone of the discussion at the Institute of Medicine meeting, that we are headed towards something more than is currently stated in the ACIP recommendations,” says Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which administers most civilian research in the United States related to diseases such as smallpox.
Fauci and others close to the immunization committee predict that it will continue to recommend against vaccinating the general public before a smallpox outbreak occurs, but that it is likely to suggest that vaccinations begin of tens of thousands of first responders who would have to investigate and contain a smallpox epidemic.
But experts differ on how widely the inoculation net should be thrown. “We have already vaccinated the groups that would go in and confirm a diagnosis, so it's a logical policy to extend that to people who are actually going to administer the vaccine if there is an outbreak,” says Jonathan Tucker, director of the Chemical and Biological Weapons Nonproliferation Program at the Washington DC office of the Monterey Institute of International Studies.
The vaccine used to eradicate smallpox in the 1960s and 1970s was grown in cows, and the United States has about 77 million doses of this vaccine on hand. But 209 million doses are being prepared of a fresh vaccine that was grown in cell culture and has not been tested in large clinical trials.
“If you did it right, the trial would be large enough to learn what we need to know about the safety of the vaccine,” says Anthony Robbins, chair of family medicine and community health at the Tufts University School of Medicine in Boston.
But not all public-health officials support this approach. Some argue that the risk of a smallpox attack does not justify exposing first responders to vaccine side-effects — vaccination causes serious side-effects in about 1 in 10,000 people. Others say that, given the hundreds of thousands of workers employed in health and emergency services in the United States, it is too hard to determine who should qualify for early vaccination.
“There is absolutely no end to the people who could justifiably be called first responders,” says Alfred Sommer, dean of the Bloomberg School of Public Health at Johns Hopkins University in Baltimore, Maryland.
Donald Henderson, also at Johns Hopkins, a former adviser to the health secretary and leader of the global campaign that eradicated smallpox, says that the government is trying to develop a safer vaccine that could be used alone or in combination with the current vaccine. The three main candidates, he says, are the LC16m8 strain, which was given to 50,000 Japanese children in the mid-1970s; the modified vaccinia Ankara strain, which was developed in Germany in the 1960s; and a genetically engineered strain of the vaccinia virus.
After hearing the committee's advice, government officials will determine who gets the smallpox vaccine. Some politicians have already called for it to be made available to anyone who wants it. Scientists who fear the public-health consequences of such an approach will press the ACIP to issue very specific recommendations on who should receive the vaccine.