The decision by the Clinton administration not to proceed with the planned destruction of its store of smallpox (page 741) is well taken. A report last month by the US Institute of Medicine did not pronounce on whether the store should be destroyed, as the United States agreed to do in 1996 under a World Health Organization plan. But it lays out a persuasive case for the potential public-health benefits of retaining the live virus, which is frozen in a maximum-containment laboratory at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, accessible to only six highly trained scientists, and at a Russian government laboratory in Siberia.

The lack of effective antiviral medications would not be of so much concern were it not for the growing vulnerability of a population that has not been routinely vaccinated now for a generation. Were the disease to re-emerge — whether accidentally or at the hands of terrorists or a rogue nation — the results could be catastrophic. Careful science under the auspices of the CDC, testing candidate medications against the virus in cell culture and, later, in monkey models, may offer the only serious weapon to respond to an epidemic, if not to prevent it.

In addition, a new, large population of the immunosuppressed now exists, thanks to organ transplantation, cancer chemotherapy and AIDS. These people deserve the potential benefit of a novel vaccine if the disease again became endemic. But development of such a vaccine would require the live virus.

Rightly, public-health advocates bemoan the prospect of any measure that increases the risk of a re-emergence of this scourge. But, given the impossibility of knowing who now possesses the virus, and from where it might appear, it is better to have a number of arrows in the quiver than to destroy the stock and cross our collective fingers.