Chicago Tribune from Chicago, Illinois • 169

POLIO Is the Killer Still with Us? I V- Dr. Salk (left) and Dr. Sabin clashed in 1955 hearings about the use of the Salk vaccine. (Continued from Page 9) 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 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." There have been problems, too, in the production of the killed Salk vaccine. An extra filtration step was added in November, 1955, Dr. Cox said, because the amount of formalin used did not inactivate the polio-virus.

We found residual live virus for as long as 42 consecutive days of inactivation." Dr. Cox went on to assert that the second filtration step was picked out of thin air with no experimentation to back it up," and that the extra filtration cut down on the effectiveness of the vaccine. Mass vaccination with the Salk product started in April, 1955, and by April 26, there were reports of paralytic polio among vaccinated children, with deaths occurring in Idaho and California. Then came cases of polio among family members of vaccinated children. Live virus was discovered in the supposedly killed vaccine, altho it had been produced by the Salk procedure.

Dr. Ratner cited numerous instances in which live viruses were found in vaccine which was presumably safe, even in Dr. Salk's own standard vaccines. It should be stressed that safety testing was inadequate when Dr. Salk developed the vaccine and when the vaccine was commercially prepared for the field trials of 1954 and for licensing and use in 1955," said Dr.

Ratner. He added that in current vaccine, potency has been sacrificed for safety and that "at present, epidemiologic methods employed by the United States public health service to assure safety of the vaccine are inadequate." Should the Salk vaccine continue to be used? "There is no known way of preventing polio with a licensed product at the present time except thru the use of the Salk vaccine," answered Dr. Kleinman. "While I am an agnostic about the effectiveness of the Salk vaccine, I still believe it does something in preventing paralysis. So we owe it to the public to recommend its use.

On the other hand, if we are going to act not only as public health physicians but as scientists we must continue our investigations into the truth about the Salk vaccine. On the basis of the facts as I know them, we must look for something better." Other panel members agreed, pointing out that because all of the facts about the Salk vaccine have not been made public, physicians and public health officials find it difficult to resist the great pressures of public opinion built up thru an unprecedented publicity campaign urging the public to be vaccinated. "Since nothing else is available, there seems to be no alternative but to push the use of it," commented Dr. Greenberg. I don't think we should do so in ignorance, nor too complacently, believing that March 5, 1961 as long as we have something partially effective, there is no need to have something better.

By being more cautious, we may make a mistake by accepting a better polio vaccine too slowly." When measured against its killed counterpart, a live virus vaccine (using modified virus which stimulate the production of anti-bodies but do not cause the disease) is always a superior vaccine," asserted Dr. Cox. He said it invariably costs much less. And it gives a higher degree of longer-lasting immunity. Dr.

Cox has developed a live vaccine which was tested on thousands of school children and adults last year in Dade county, and also on thousands of persons in foreign countries. Another live, oral polio vaccine has been developed by Dr. Hilary Koprowski, of Philadelphia's Wistar institute and has been tested on approximately 9 million individuals. Dr. Koprowski has challenged the United States public health service decision last August to grant approval only to the Sabin vaccine.

In a letter in the Jan. 14 Journal of the American Medical association, he said, "Altho it is a step forward that the principle of live virus immunization in poliomyelitis has at last been officially accepted, I am taking strong exception to this exclusive indorsement of one set of strains. In my opinion, such an indorsement should evoke a protest from individuals who believe that fair scientific judgment should be the basis for decisions affecting the physical welfare of man." Amplifying his letter, Dr. Koprowski said, "It is my belief that government decisions, which are not based on proper evaluation of scientific data, are prompted by either poor choice of scientific advisers or by cryptic reasoning and that such ill-advised decisions could lead to development of an unhealthy climate in which scientists will see their contributions trampled upon by administrative agencies." Discussing the development of live, oral vaccines. Dr.

Cox explained, "Polio is unique because many more people get the infection than the disease." The problem in producing a live vaccine is to modify, or tame, the virus so that they will produce a mild infection strong enough to stimulate the formation of antibodies, but not the disease itself. A complicating factor in taming polio virus, is that three separate, tamed strains have to be developed to produce antibodies against the three chief types of polio. A killed vaccine, such as the Salk, does not immunize an individual against an infection of polio virus in the intestines and, altho it can induce antibodies in the blood, this does not prevent the individual from becoming a carrier and spreading polio-virus, explained Dr. Cox. Individuals receiving the live, modified, oral vaccines also eliminate poliovirus from their bodies for several days or several weeks after vaccination, but these are the tame, modified strains.

Family contacts and even other individuals in the neighborhood can also acquire an immunity from these tame virus, altho they have never received the vaccine themselves. However, some experts still fear that one of these strains may revert to its virulent type as it is passed from one individual to another, according to a report by Dr. Roderick Murray's committee, quoted in the Oct. 15, 1960, issue of Modern Medicine." One solution, the committee suggested, might be to give the oral vaccine to entire communities in a brief time. This is a problem which must be solved before the Sabin vaccine is licensed.

Dr. Cox stated that using a live vaccine is the only way to eliminate wild, virulent polio strains in nature. Immunization with live vaccine probably would not protect a person for life, he added, but it would be cheap enough so you could afford it once a year. Dr. Ratner compared Dr.

Cox's vaccination figures with the 1954 field trials of the Salk vaccine. The Cox live poliovirus has now been used by many investigators in over 2.5 million people, the other two live virus vaccines under study have been used in additional millions," he said. Safety has been paramount in the minds of these investigators." On the other hand, Salk vaccine was used in only 400,000 persons in a single field trial which assumed safety and was primarily designed to determine effectiveness. An objective and fearless evaluation of the Salk vaccine is needed, for this is the necessary ingredient of an intelligent decision as to when the live virus vaccine should be licensed," Dr. Ratner continued.

Obviously, if the Salk vaccine is safe and highly effective, the United States public health service can take its time about licensing the live virus vaccine. If, on the other hand, polio and polio epidemics remain with us and children become paralyzed despite three, four, five, and six inoculations of Salk vaccine and vaccinees die, we cannot take our time." What should parents do? Take the advice of their pediatrician or family doctor and not be stampeded by TV commercials or overly-enthusiastic claims for vaccines. It is the individual physician who must decide which vaccine is safe and effective in what circumstances. But physicians must have, honest, impartial, fully scientific information available to make this decision. Currently, most physicians are still giving Salk vaccine shots.

A few doctors do not. Some give them only if patients insist, i Once a live, oral vaccine is fully approved, it will be more effective than the killed Salk vaccine. Because of the doubt about the potency and effectiveness of the Salk vaccine in the past, a full course of the new vaccine will undoubtedly be recommended for everyone, regardless of how many Salk shots each individual has had. I I.