21.   The question, of course, is whether it is worthwhile to risk unleashing live viruses that might still be in the frozen tissue of the miners.

22.   The smallpox vaccine involves injecting live virus into an individual and prompting the creation of antibodies to maintain immunity.

23.   This makes it difficult to tell a vaccinated animal from one harboring live virus.

24.   To be avoided are live virus and bacterial vaccines, including those for measles, mumps, rubella and chicken pox.

25.   Two months later, he infected one group with live Ebola virus.

26.   Unlike some other vaccinations, AIDSVax does not contain live virus.

27.   Who wanted to fool around with live infectious viruses when you could pop a few penicillin pills and be as good as new?

28.   Who wanted to fool around with live infectious viruses when you could pop a few penicillin pills?

29.   You are almost certain to find pages that will let you download live viruses.

30.   But because it is made with a live virus, it causes about eight people in the United States each year to become infected with polio.