Federal health officials are trying to prepare for just such an attack. They have requested $509 million to add an additional 300 million doses of smallpox vaccine to the United States' current stock of 15.4 million doses by sometime next year. The effort, says Health and Human Services Secretary Tommy Thompson, is intended to protect Americans from the virus.
Smallpox is a highly contagious virus that kills one in three of the infected. The virus is spread from person to person through droplets from the nose or mouth, direct contact, or contaminated clothing or bedding. Some Americans have been vaccinated against smallpox but are unlikely to be protected from the deadly virus since immunity from the vaccine lasts only 10 years. Although the disease was declared eradicated worldwide in 1977, some virus remains in laboratories.
Some fear that if terrorists got their hands on this supply, they could start a smallpox epidemic with just a single infected person a "smallpox martyr."
Since there is no primary treatment for the virus, experts say if an outbreak were to occur, quarantine and vaccination would be the primary strategies for forestalling it. First to be vaccinated would be emergency workers and those who may have been in contact with infected patients. Vaccination should be done as early as possible, and as late as four days after exposure.
Despite the logistical challenges, a smallpox outbreak could be manageable, says Dr. Sean Palfrey, a public health professor at Boston Medical Center.
"In the event of an emergency, the CDC [Centers for Disease Control and Prevention] would make its stock of doses available to the area of outbreak within two hours. They would probably vaccinate anyone with face-to-face contact within four days," says Palfrey. "The current stock is more than needed even if it's a significant outbreak."
Because the vaccine supplies are limited, vaccination efforts would likely focus on high-risk people. "Health officials would get it to anybody they could," says Palfrey, adding that immune-compromised individuals such as those with asthma, cancer, AIDS and even skin conditions like eczema would get first priority.
"In a global sense, all individuals are just as likely to contract the disease," says Palfrey. "The difference is that a person with a weak immune system would have, say, a 60 percent chance of dying from it while a healthy person might have a 25 percent chance."
A Question of Quarantine
The prospect of quarantine, however, could pose considerable legal and medical problems in a country that hasn't known the practice since the 1800s, and even has some medical professionals concerned.
"Quarantining Americans could potentially infringe on civil rights," says Dr. Michael Allswede, an associate professor of emergency medicine at the University of Pittsburgh.
Symptoms of smallpox infection usually begin two weeks after exposure to the virus, with fever, headache, backache, and the characteristic skin rash.
The telltale "smallpox" a disfiguring, scabby rash spreads to the chest, back and legs a little more than a week later. Death occurs in the second week of illness in approximately 30 percent of patients.
Considering the Risks
With such a grim profile, many experts wonder if mass vaccination is the most logical option.
Vaccination was last given in this country as a public health measure in 1972. Risks such as encephalitis may occur in up to three of every 1 million people vaccinated. In addition, up to 250 of every million people vaccinated can develop a potentially fatal smallpox-like rash caused by the vaccine itself.
In the absence of a confirmed smallpox case, the risks of the vaccine are said to outweigh the benefits. But has the equation changed?
"If smallpox is a credible threat, we should be immunizing," says Dr. Anne Gershon, the director of pediatric infectious disease at Columbia University in New York. "But if we didn't have to use the vaccine, we'd be better off."