Word: viruses
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Dates: during 1950-1959
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...Even when manufacturers used every precaution known, the process of making a potentially deadly virus into a safe vaccine proved unexpectedly tricky. When three separate strains of virus, all officially dead by available tests, were pooled to make the final polyvalent vaccine, the mixture sometimes showed live virus. And some virus defied every effort to kill...
...Salk re-examined his straight-line theory of how the virus is inactivated to make vaccine. According to this, he can start with a virus brew so potent that there are 4,000,000 virus particles in every teaspoonful. But after 1½ days in formaldehyde there should only be 4,000 alive, after three days only four, and after nine days only a single active particle in a ton. If things did not work this way in practice. Dr. Salk argued, it must be because of ''fractional inactivation." This might result from the clumping of virus particles...
Weakening Strain. This sort of thing apparently had not happened in Dr. Salk's own labs. But if it could happen anywhere, it raised a fundamental question: should any strain of virus that is likely to cause paralysis be used in the vaccine? Dr. Salk had long contended that the Mahoney strain which he picked to represent all the Type I strains, was safe because it was killed; critics had damned it in the live state as the most virulent form known, and the likeliest to cause paralysis. Now, Dr. Salk wavered: Mahoney was a good strain because...
...P.H.S.'s top men were not entirely satisfied with formaldehyde as the killing agent: ironically, it may actually favor the clumping of virus particles that makes a vaccine unsafe. And they had little patience with the Mahoney strain (which has caused most of the polio in the Cutter-vaccinated cases).* Denmark, they noted, has inoculated its 400,000 schoolchildren with a Salk-type vaccine, but with the Brunhilde strain substituted for Mahoney, and with no mishap. And since the U.S. authorities were not satisfied with present testing methods, it was clear that major changes in the Salk vaccine were...
...August and September, months that mark the height of the polio season in virtually all the U.S.? This question involves a cruel choice: vaccine given in August may give life-saving protection against polio in September. But any injection at that time may provoke a paralytic reaction from virus already smoldering in the system, which might otherwise have done no harm. As of last week, most Government experts seemed inclined to go ahead anyway, but many a doctor was doubtful. Newark and other New Jersey cities postponed vaccinations...