Smallpox Vaccines For Everyone?

By Alice Park

As anxious as the country is over anthrax, the isolated outbreaks are only a lukewarm version of what a true infectious-disease hot zone would look like. Because anthrax is rarely contagious, the exposures to the bacteria have been well contained. But with other agents, that may not be so easy. Smallpox in particular has public health officials concerned. Since 1980, when the World Health Organization declared that the disease had been eradicated, the world's population has not been vaccinated. The U.S. ended routine immunizations in 1971, and even for those who got the shots as children, the vaccine's period of effectiveness has expired.

As a tool of destruction, the smallpox virus is ideal. Simply exposing people to the bug in its natural state, without significantly manipulating or processing it, is sufficient to seed an epidemic. Unlike anthrax, smallpox is highly contagious (just one infected person could cause the virus to radiate from a family to a neighborhood to a city in a matter of months), and smallpox cannot be treated effectively once symptoms begin (30% of those infected will die). The vaccine is 100% effective, but only in protecting against the disease before exposure. Although studies show that inoculation can prevent infection if given up to four days after exposure, by the time the first symptoms appear--fever, headache and rash, which begin at least two weeks after exposure--it is too late.

The world's two remaining samples of smallpox virus are stored at secure facilities in the U.S. and Russia. But there is evidence that Iraq, North Korea and Russia researched ways to grow and deliver smallpox in large quantities and still retain undeclared stores. With that in mind, and with the threat of bioterrorism now more palpable, officials at the Department of Health and Human Services have discussed, for the first time in two decades, the possibility of inoculating the public again. As a precaution, the government has accelerated the delivery of a pre-existing order for 40 million more doses of the vaccine for the national pharmaceutical stockpile to add to the 15.4 million doses already stored at undisclosed locations. Originally due in 2004, the first doses will be delivered by next summer. HHS Secretary Tommy Thompson is also talking to four drug companies about producing 300 million more doses by next year--enough to inoculate every American. In the meantime, Thompson has also authorized researchers to determine whether diluting existing doses by five or 10 times could boost supply quickly without sacrificing the vaccine's potency.

But is it a good idea for the U.S. to begin vaccinating all Americans again? Though it could neutralize one major bioterrorist weapon, there are strong arguments against it. The shots themselves carry risks. Historically, for about two out of every 1 million people inoculated, the vaccine's weak virus strain caused brain infection and death; others developed a mild but still unpleasant poxlike viral infection. More worrisome is the fact that the number of people most vulnerable to these adverse effects--those with compromised immune systems, such as patients in chemotherapy or with AIDS--has increased considerably since the last mass inoculations. Most experts believe that only a confirmed case of smallpox would justify taking these risks again with a nationwide vaccination program.

--By Alice Park