July 5, 2002

The federal government will soon vaccinate roughly a half-million health care and emergency workers against smallpox as a precaution against a bioterrorist attack, federal officials said. The government is also laying the groundwork to carry out mass vaccinations of the public — a policy abandoned 30 years ago — if there is a large outbreak.

Until last month, officials had said they would soon vaccinate a few thousand health workers and would respond to any smallpox attack with limited vaccinations of the public. Since 1983, only 11,000 Americans who work with the virus and its related diseases have received a vaccination, according to the Centers for Disease Control and Prevention.

The plan to increase the number of "first responders" who receive the vaccination to roughly 500,000 from 15,000 and to prepare for a mass undertaking of vaccinations in effect acknowledges that the government's existing program is insufficient to fight a large outbreak.

The government's new vaccination safeguards come amid continued talk in Washington of war against Iraq, which terrorism experts suspect of maintaining clandestine stocks of the virus, as well as growing criticism of the government's limited plan. Only Russia and the United States have declared stocks of the virus.

A highly contagious disease, smallpox was declared eradicated globally in 1980, eight years after the United States stopped routine vaccinations.

Until its eradication, smallpox killed roughly one in three people who were infected but not vaccinated. Because immunity is believed to diminish with time, most people alive today are considered vulnerable to smallpox. But federal officials have long resisted the resumption of mass smallpox vaccinations, citing the probable risk of serious side effects, even death.

Last month, a federal advisory panel backed a plan for "ring vaccinations," in which health workers would isolate infected patients and vaccinate people in close contact with them, forming a ring of immunization around an outbreak and a barrier to its spread. In theory, such a strategy can work because the vaccine, if given within four days of exposure to the virus, protects people from the disease.

Some experts on infectious disease said the plan's main virtue was that it required little smallpox vaccine.

The government's more aggressive plans are possible because vaccine supplies are rapidly increasing as a result of crash manufacturing and stockpiling efforts begun soon after last fall's terrorist strikes, officials said. Also, studies have found that existing vaccine doses can be diluted without loss of effectiveness.

"Now we can act differently because we have more vaccine," Dr. Donald A. Henderson, senior science adviser to Tommy G. Thompson, the secretary of health and human services, said in an interview. Dr. Henderson, who led the global smallpox eradication effort, added that in a crisis "we can make vaccine available on request throughout the community."

Officials said that about 100 million doses of the smallpox vaccine (160 million if diluted) are in hand and that by late this year or soon thereafter enough will be available for every American, more than 280 million people.

Health and military experts, citing new models of how the contagion can spread and new disclosures about how the weaponized virus can sail on the wind, have recently argued that limited, local vaccinations could produce thousands if not millions of needless infections and deaths. Most critics of the ring vaccination plan advocate mass vaccinations of the United States population — but often before a smallpox attack, not after, as the government is now planning.

In addition to vaccinating more "first responders," the government plans to develop ways to speed vaccine deliveries around the country and help states plan how to carry out mass vaccinations after an attack.

Officials said the vaccinations of hospital workers and smallpox response teams, to begin fairly soon, would help train health professionals in smallpox vaccination and educate the public to the attendant risks.

The White House, Defense Department and other federal agencies are involved in the vaccination planning. "Everyone is aware," an administration official said.

Jerome M. Hauer, acting assistant secretary for emergency preparedness at the Department of Health and Human Services, said the agency hoped to send planning documents on how to best conduct mass vaccinations to cities and states in the next week or two. Mr. Hauer added that logistics changes to that end were under way at the Centers for Disease Control and Prevention in Atlanta, which oversees the production, safekeeping and distribution of the nation's stockpile of smallpox vaccine.

Other details of the plans, such as who would receive peacetime vaccinations, have yet to be approved by Mr. Thompson, officials said.

In interviews last week, health officials said the government had not abandoned its longstanding plan for ring vaccinations of people near a smallpox outbreak, the approach health workers used decades ago to eradicate the highly contagious disease from human populations. But the added steps, officials said, will make it possible to move far more aggressively if a terrorist attack ends up infecting more than 100 people or so.

Critics had said the ring approach, while useful in battling natural outbreaks, would do little or nothing against a moderately skilled enemy intent on mayhem.

"Unless the initial attack is very small and the infectiousness of the agent is quite mild, ring vaccination is not going to do much good," said Edward H. Kaplan, a Yale public health specialist who questioned the method's value at a federal meeting in Washington three weeks ago.

In a report, the Cato Institute, a policy group in Washington, called ring vaccination "woefully inadequate for countering a direct attack."

Critics argued that a number of factors had diminished the method's effectiveness since the disease was eradicated in 1980: populations are now increasingly mobile, levels of immunity are very low and advanced technologies have become commonplace, raising the odds that a smallpox attacker would be at least moderately skilled.