31.   Nilsson and his wife are still weighing the risks of the polio vaccine.

32.   One victim was a worker in a laboratory where polio vaccine was being developed, he said.

33.   Oral polio vaccine continues to be recommended as the most effective prevention in parts of the world where polio remains endemic.

34.   Parents of two children infected with the disease as a result of oral polio vaccine were among those who made comments at a public hearing on Wednesday.

35.   Salk never lost faith in killed virus polio vaccine and continued to champion its cause all his life.

36.   Shortly after people began using the polio vaccine, a drug manufacturer mistakenly left live virus in a batch, causing several cases of polio.

37.   She said she believes his approach could prolong life in the next century the way polio vaccines did in this one.

38.   Shortly after people began using the polio vaccine, a manufacturing mistake left live virus in a batch, causing several cases of polio.

39.   Still, even if it reaches the market, Remune will be just one drug in an arsenal and will not have a similar effect to the polio vaccine.

40.   The federal agency in Atlanta prepared samples that included old polio vaccine that it had kept stored and other material that were used as controls for scientific purposes.