Unintentional Manipulation

of Polio Statistics in the 1950s

Dr. Bernard Greenberg was chairman of the Committee on Evaluation and Standards of the American Public Health Association during the 1950s. He testified at a panel discussion that was used as evidence for the congressional hearings on the polio vaccine in 1962.

During these hearings, Dr. Greenberg discussed the problems associated with polio statistics and disputed claims for the vaccine's effectiveness.

A biostatistics expert, Dr. Greenberg attributed the dramatic decline in polio cases to a change in reporting practices by physicians. The reason fewer cases of polio began to be identified, he testified, had nothing to do with the polio vaccine.

An excerpt from Dr. Greenberg's testimony:

"Prior to 1954, any physician who reported paralytic poliomyelitis was doing his patient a service by way of subsidizing the cost of hospitalization and was being community-minded in reporting a communicable disease.

"The criterion of diagnosis at that time in most health departments followed the World Health Organization definition:

'Spinal paralytic poliomyelitis: signs and symptoms of nonparalytic poliomyelitis with the addition of partial or complete paralysis of one or more muscle groups, detected on two examinations at least 24 hours apart.'

"Note that 'two examinations at least 24 hours apart' was all that was required [for an official diagnosis of polio]. Laboratory confirmation and presence of residual paralysis was not required.

"In 1955 the criteria were changed to conform more closely to the definition used in the 1954 field trials: residual paralysis was determined 10 to 20 days after onset of illness and again 50 to 70 days after onset. . . .

"This change in definition meant that, in 1955, we started reporting a new disease, namely, 'paralytic poliomyelitis with a longer-lasting paralysis.' Furthermore, diagnostic procedures have continued to be refined. Coxsackie virus infections and aseptic meningitis have been distinguished from paralytic poliomyelitis. Prior to 1954 large numbers of these cases undoubtedly were mislabeled as paralytic poliomyelitis.

"Thus, simply by changes in diagnostic criteria, the number of paralytic cases was predetermined to decrease in 1955-1957 -- whether or not any vaccine was used."

Quoted material from "Intensive Immunization Programs, Hearings before the Committee on Interstate & Foreign Commerce, House of Representatives, 87th Congress, 2nd Session on H.R. 10541," Washington, DC: U.S. Government Printing Office, 1962; p. 96-97