Last Updated

14 Dec 2002

Source: Reuters, June 17, 2002.

US Officials Unfazed by Soviet Smallpox Report

By Todd Zwillich

WASHINGTON (Reuters Health) - Saturday's release of a surprising new report detailing the possible environmental release of weaponized smallpox in the Soviet Union in 1971 has so far done little to make US officials rethink this country's evolving strategy for countering a smallpox attack.

The report raises disturbing questions about the possible existence of a smallpox strain able to float many miles on the air and still infect people, according to experts attending a National Academy of Sciences forum on smallpox vaccination strategies over the weekend.

It also could force officials to consider that the strain responsible for the Soviet outbreak that sickened seven previously vaccinated people and killed three with the rare hemorrhagic form of smallpox could skirt the immunity provided by existing US vaccine stores, they cautioned.

A copy of the report was leaked to The New York Times in advance of Saturday's meeting of the Monterey Institute of International Studies.

The report comes as expert boards at the US Centers for Disease Control and Prevention (CDC) are preparing this week to issue recommendations on how smallpox vaccine stockpiles should be used to minimize the damage of a possible terrorist attack.

Experts could recommend widespread availability of vaccine or more restrictive use confined to health workers or emergency first responders. The recommendation and any policy decision that follows it largely depend on the perceived likelihood of an attack and on the infectivity of the virus terrorists could use.

But top US health officials interviewed by Reuters Health said too little is known about the details of the outbreak to consider altering bioterror response plans. Even if the outbreak's "worst-case scenario" -- the previously unknown existence of an aerosolized and modified smallpox strain -- were realized, little could be done today to counter it, they said.

The Monterey Institute's experts are being "alarmist" about the previously unknown outbreak, said D.A. Henderson, a smallpox expert and the Bush administration's lead advisor for public health preparedness. "I don't think there's anything here," he said.

The report describes an outbreak that started in August 1971 when a 24-year-old woman became ill with smallpox. The woman was one of 12 people aboard an ecological research ship that sailed within 15 km of a bioweapons research facility perched on an island in the Aral Sea.

One other woman working aboard the ship was infected. Both women had been vaccinated against smallpox, as had five others in shore communities who eventually fell ill. Three non-vaccinated infants died, all of rare but highly fatal hemorrhagic smallpox.

Studies from 11,000 smallpox cases in a 1971 Asian outbreak showed that only 140, or 1.3%, were of the hemorrhagic variety.

Records of the three Soviet fatalities worried the Monterey experts. Hemorrhagic smallpox was not only rare compared with other smallpox forms but was especially uncommon in infants, said Alan Zelicoff, senior scientist at the Center for Security and Arms Control at the Department of Energy's Sandia National Laboratories.

The possibility that 30% of the total illnesses in the Soviet outbreak were hemorrhagic cases suggests that Russian researchers may have produced a smallpox strain designed to cause more serious disease, Zelicoff told experts at the meeting.

But most US experts focus on host factors such as a person's age, sex, and level of immunity and not on the possibility of modified viruses when considering US vaccination policy.

"(It's) the explanation you're not allowed to bring up," Zelicoff said.

He urged US planners to consider changing viral factors in their smallpox response scenarios. Plans should include much greater emphasis on finding new drugs to help combat modified strains in case the hundreds of millions of doses of smallpox vaccine the government is currently stockpiling are ineffective.

"We can't be satisfied with making 300 million doses of the vaccine, as good as it is," Zelicoff said. "It's not over when we have all of the doses."

Others said that the newly discovered reports should lead officials to strongly consider mass-vaccinating parts or all of the US population in anticipation of a possible smallpox attack by terrorists.

"It tips the equation almost 180 degrees. We need to plan for a realistic scenario," said Dr. Peter B. Jahrling, principle scientific advisor at the US Army Medical Research Institute of Infectious Disease.

But Henderson said that he doubted that the clinical descriptions and autopsy details in the report suggest that two of the three fatal smallpox cases in the Soviet outbreak were not hemorrhagic. He also said it was unclear how much time had elapsed since other ill persons in the outbreak had been vaccinated, stressing that no vaccine confers lifelong immunity.

And even if evidence suggested the use of a virus that escapes immunity, "there's nothing we can do about it," Henderson said. Without a sample of the virus, which Russian authorities are unlikely to hand over to US researchers, an effective vaccine against it cannot be made, he said.

Dr. Harold Margolis, the CDC's senior advisor for smallpox preparedness, dismissed Zelicoff's interpretations of how infective the smallpox was in the Aral Sea cases as "speculation." He said that while the 24-year-old woman aboard the ship might have been infected by a weaponized smallpox release, that explanation was not conclusive.

"How she actually got it is open to question. To me this doesn't change our knowledge about the disease and how it behaves," Margolis said.

"I don't see this (report) off the top modifying any policies," added Dr. Anthony Fauci, director of the National Institutes of Allergy and Infectious Diseases and an advisor to President Bush on bioterrorism policy.

Still, Henderson said of the smallpox strain responsible for the 31-year-old Soviet outbreak, "we would really like to have it."