Discussing the “very misleading way” in which the Salk vaccine data has been handled, was Bernard G. Greenberg, Ph. D., head of the department of bio-statistics of the University of North Carolina, school of public health, and former chairman of the committee on evaluation and standards of the American Public Health association.

“There has been a rise during the last two years in the incidence rates of paralytic poliomyelitis in the United States,” stressed Dr. Greenberg. “The rate in 1958 was about 50 per cent higher than that for 1957, and in 1959 about 80 per cent higher than that in 1958. If 1959 is compared with the low year of 1957, the increase is about 170 per cent.

“As a result of this trend in paralytic poliomyelitis, various officials in the public health service, official health agencies, and one large voluntary health organization have been utilizing the press, radio, and television and other media to sound an alarm bell in an heroic effort to persuade more Americans to take advantage of the vaccination procedures available to them,” said Dr. Greenberg.

“Altho such a program might be desirable until live virus vaccines are available to us on more than an experimental basis, the misinformation and unjustified conclusions about the cause of this rise in incidence give concern to those interested in a sound program based on logic and fact rather than personal opinion and prejudice.

“One of the most obvious pieces of misinformation being delivered to the American public is that the 50 per cent rise in paralytic poliomyelitis in 1958 and the real accelerated increase in 1959 have been caused by persons failing to be vaccinated. This represents a certain amount of double talk and an unwillingness to face facts and to evaluate the true effectiveness of the Salk vaccine,” said Dr. Greenberg.

The number of persons over 2 years of age in 1960 who have not been vaccinated cannot be more and must be considerably less than the number who had no vaccination in 1957, Dr. Greenberg pointed out. Then how can it be claimed that it is the large number of unvaccinated persons who are causing the increase in polio, when there were a larger number of unvaccinated individuals in 1957 when the vaccine was given credit for reducing rates of the disease.

“A scientific examination of the data and the manner in which the data was manipulated will reveal that the true effectiveness of the present Salk vaccine is unknown and greatly overrated,” Dr. Greenberg stressed.

Why was there such a tremendous reduction in reported rates of paralytic polio in 1955, 1956, and 1957? Much of this highly publicized decrease was a statistical illusion, said Dr. Greenberg.

Prior to 1954, any physician who reported a case of paralytic poliomyelitis was doing his patient a favor because funds were available to help pay his medical expenses. At that time, most health departments used a definition of paralytic poliomyelitis which specified ” partial or complete paralysis of one or more muscle groups, detected on two examinations at least 24 hours apart.” Laboratory confirmation and the presence of residual paralysis were not required.

In 1955, these criteria were changed. Now, unless there is paralysis lasting at least 60 days after the onset of the disease, it is not diagnosed as paralytic polio.

During this period, too, “Coxsackie virus infections and aseptic meningitis have been distinguished from paralytic poliomyelitis,” explained Dr. Greenberg. “Prior to 1954, large numbers of these cases undoubtedly were mislabeled as paralytic polio.”

Thus, because the definition of the disease was changed and two similar diseases virtually ruled out, the number of cases of polio reported was sure to decrease in the 1955-57 period, vaccine or not. Then, too, physicians are reluctant today to diagnose paralytic poliomyelitis in a vaccinated child without thoro laboratory tests, thus eliminating most of the false positive cases commonly reported in the pre-1954 period.

“As a result of these changes in both diagnosis, and diagnostic methods, the rates of paralytic poliomyelitis plummeted from the early 1950s to a low in 1957,” said Dr. Greenberg. The recent increase in the disease, despite improved diagnostic methods, he believes, is due to a long term, increasing trend in the occurrence of polio.

“Without doubt, the increasing trend has been reduced to some extent by the Salk vaccine,” explained Dr. Greenberg. ” Nevertheless, the Salk vaccine has ‘ limited effectiveness in its ability further to reduce this trend. . . . Any future substantial reduction in this trend will require a more potent vaccine, not simply vaccinating more people.

“Today it may be a serious mistake to be ultra-conservative in accepting the various new live vaccines under the impression that there is no hurry because an almost equivalent immunizer exists in the Salk vaccine. A delay in accepting and promoting better vaccines will be a costly one. There must be immediate pressure applied to determine whether or not the new vaccines are more effective, so that we do not cling, for sentimental or personal reasons, to an older vaccine whose true effectiveness is today unknown.”

The most accurate way we have of determining the effectiveness of vaccine (except by direct exposure to the disease) is to measure the levels of neutralizing antibodies in the blood, explained Herald R. Cox, Sc. D., director of virus research at Lederle Laboratories and president elect of the Society of American Bacteriologists. We do not know, he said, the exact level of antibodies necessary to protect against paralytic polio.

Herman Kleinman, M. D., an epidemiologist from the Minnesota department of health, pointed out that in antibody studies on children who have received three or more doses of Salk vaccine, he has found more than half do not have antibodies to two of the three types of polio strains used in the Salk vaccine. Twenty per cent lack antibodies to a third type.

“This is a very disturbing fact,” said Dr. Kleinman. “If polio antibodies mean anything in respect to protection, then I am forced to conclude that much of the Salk vaccine we have been using is useless.”

Dr. Kleinman also commented on the “changing concept of polio” and said physicians were reluctant to diagnose the disease without overwhelming evidence. He called the insistence on a 60 day duration of paralysis in defining paralytic polio ” silly.”

Dr. Cox, who has worked in the virus field since 1929 and was the first person to prove that a killed vaccine could be made, commented on some of the problems of producing a potent, killed-virus vaccine.

“We are now learning, not only in the United States, but in Israel, England, and Denmark, that the killed product does a fairly good job of producing antibodies against Type II poliovirus,” said Dr. Cox. “But Type II represents only about 3 per cent of paralytic cases thruout the world. The killed vaccine does a poor job against Type I, however, which, causes 85 per cent of paralytic cases, and against Type III, which causes about 12 per cent.

“In other words, the killed vaccine is doing its best job against the least important type. It took time to find this out. It was proven in Israel in 1958, when it had its big Type I epidemic. They did not see any difference in protection between the vaccinated and the unvaccinated. Last year in Massachusetts during a Type III outbreak, there were more paralytic cases in the triple vaccinates than in the unvaccinated.”