21.   Last week, with the U.S. and Russia reversing earlier decisions to destroy the smallpox virus, the World Health Organization granted the virus yet another stay.

22.   Modern science has found that the smallpox virus, known as variola, is a monster in size, possessing one of the largest genetic blueprints of any virus.

23.   No country has divulged outdoor tests of the smallpox virus, which causes high fevers and usually kills one in three unvaccinated people.

24.   North Korea and other countries are believed to have clandestine supplies of smallpox virus as well.

25.   One factor is that health care workers would likely have a greater risk of exposure to smallpox virus than the average person.

26.   Of these, experts agree, the smallpox virus is in a class by itself.

27.   One of the deadliest, now that people are no longer vaccinated against it, is the smallpox virus, which causes devastating epidemics in unprotected populations.

28.   One was a pioneer of genetic engineering who had decoded the smallpox virus and other microbes and used the meeting to push his own scientific agenda, participants said.

29.   Or release smallpox virus into the BART system.

30.   One purpose of the study was to test the effectiveness of various drugs against the smallpox virus in test tubes.