The Salk vaccine against paralytic polio may be even more effective than the statistics have shown. Since wide-scale vaccination began in 1955, there have been hundreds of reported cases of paralysis among people who had had one or two shots (only a handful among those who had had three). But in last week's A.M.A. Journal, a University of Pittsburgh team headed by Dr. William McD. Hammon
(TIME, Nov. 3, 1952) reported evidence that casts doubt on these figures.
Difficulty is that the poliomyelitis virus belongs to a family of at least three enteroviruses (so called because they can multiply in the gut) that...