The Creation and Production of the Polio Vaccines

In the 1950s, scientists like Doctors Jonas Salk and Albert Sabin had isolated the poliovirus strains to make vaccines.[1] Dr. Salk’s strains would be inactivated with formaldehyde and injected into children. Dr. Sabin’s strains would be attenuated or weakened by transferring or passaging[2] the live viruses through different host cells and then fed to children orally.

Because his goal was to create a live attenuated vaccine, Dr. Sabin had to isolate the poliovirus strains and then passage the strains through a myriad of host cells in order to attain the right virulence—strong enough to illicit an immune response, but weak enough so as to not cause polio in the recipient. Sabin’s oral polio vaccine (OPV) is a trivalent vaccine and was, therefore, comprised of three types – Type I, II, and III. For example, Type I has the following lineage: In 1941, Drs. Francis and Mack isolated the Mahoney poliovirus “from the pooled feces of three healthy children in Cleveland.” [3] Dr. Salk then subjected the strain to passages through fourteen living monkeys and two cultures of monkey testicular cultures.[4] In 1954, the strain (now called Monk14 T2) was given to Drs. Li and Schaeffer who subjected the virus to nine more passages through monkey testicular cultures.[5] Next, the strain (now called Monk14 T11) underwent fifteen more passages in monkey testicular cultures, eighteen passages in monkey kidney cells, two passages through the skin of living rhesus monkeys, and additional passages through African Green monkey skin and monkey kidney cell cultures.[6] This strain was now called MS10 T43 or LS-c. In 1956, Dr. Sabin took this virus and passaged it through seven cultures of African Green Monkey kidney cells.[7]That same year, the pharmaceutical company, Merck, Sharp & Dohme, passed the strain (now called LS-c, 2ab/KP₂) through a rhesus monkey kidney cell culture.[8] The resulting material was called Sabin Original Merck (SOM) and was provided to Lederle in 1960 as the seed material to manufacture its polio vaccine. Types II and III were created in a similar fashion.[9]

Once their strains were isolated, pharmaceutical companies needed a method to propagate the viruses in order to produce the vast quantities of vaccine needed for nation-wide immunization campaigns. This required a substrate upon which the poliovirus could be efficiently grown and harvested. Kidney cells from rhesus monkeys were chosen because they were found to be an effective growth medium.[10] A small quantity of poliovirus could be added to the minced kidneys surgically removed from these monkeys and within a few days, large quantities of poliovirus could then be harvested from these same monkey cells.

There was a problem, however, with using these monkey kidney cells to both create the original vaccine strains and grow the vaccine in large quantities. Monkeys contain simian viruses.[11] When the poliovirus was passaged through the monkeys or grown on the monkey kidney cells for production, extraneous viruses became part of the final poliovirus vaccine.[12] As early as 1953, Dr. Herald R. Cox, a scientist working at Lederle Laboratories, one of the polio vaccine manufacturers, published an article in a peer reviewed scientific journal in which he stated, “[P]oliomyelitis virus has so far been cultivated only in the tissues of certain susceptible species—namely, monkey or human tissues. Here again we would always be confronted with the potential danger of picking up other contaminating viruses or other microbic agents infectious for man.”[13] In fact, in 1958, a scientific journal reported that “the rate of isolation of new simian viruses (from monkey kidney cells) has continued unabated.”[14] Additionally, in 1960, the pharmaceutical company Merck & Co. wrote to the U.S. Surgeon General:

Our scientific staff have emphasized to us that there are a number of serious scientific and technical problems that must be solved before we could engage in large-scale production of live poliovirus vaccine. Most important among these is the problem of extraneous contaminating simian viruses that may be extremely difficult to eliminate and which may be difficult if not impossible to detect at the present stage of the technology.[15]

The Discovery of Simian Virus 40 (SV40)

Between 1959 and 1960, Bernice Eddy, Ph.D., of the National Institute of Health (NIH) examined minced rhesus monkey kidney cells under a microscope.[16] These were the cells of the same species of monkeys used to create and produce the oral polio vaccine. Dr. Eddy discovered that the cells would die without any apparent cause. She then took suspensions of the cellular material from these kidney cell cultures and injected them into hamsters. Cancers grew in the hamsters.[17] Shortly thereafter, scientists at the pharmaceutical company Merck & Co. discovered what would later be determined to be the same virus identified by Eddy.[18] This virus was named Simian Virus 40 or SV40 because it was the 40th simian virus found in monkey kidney cells.

In 1960, Doctors Benjamin Sweet and Maurice Hilleman, the Merck scientists who named the virus SV40, published their findings:

Viruses are commonly carried by monkeys and may appear as contaminants in cell cultures of their tissues, especially the kidney . . . . The discovery of this new virus, the vacuolating agent, represents the detection for the first time of a hitherto “non-detectable” simian virus of monkey renal cultures and raises the important question of the existence of other such viruses . . . . As shown in this report, all 3 types of Sabin’s live poliovirus vaccine, now fed to millions of persons of all ages, were contaminated with vacuolating virus.[19]

The vacuolating virus was another name for SV40.

In 1962, Dr. Bernice Eddy published her findings in the journal produced by the Federation of American Societies for Experimental Biology. She wrote:

There is now an impressive list of oncogenic (cancer causing) viruses—the rabbit papilloma, polyoma, Rous sarcoma, the leukemia viruses . . . . It has been known for a number of years that monkeys harbor latent viruses . . . . The (SV40) virus was injected at once into 13 newborn hamsters and 10 newborn mice. Subcutaneous neoplasms indistinguishable from those induced by the rhesus monkey kidney extracts developed in 11 of the 13 hamsters between 156 and 380 days . . . .[20]

Subsequent studies performed in the early 1960s demonstrated that SV40 caused braintumors in animals[21] and that SV40 could transform or turn cancerous normal human tissuein vitro.[22] A disturbing experiment performed during this era also suggested that SV40 could cause human cancers in man in vivo.[23] In 1964, Fred Jensen and his colleagues took tissue from patients who were terminally ill with cancer.[24] They exposed the tissue to SV40 and then after it was transformed, they implanted the tissue back into the patient.[25]These implants grew into tumors in their human hosts.[26] This suggested the possibility that SV40 could cause cancers in man.

New Regulations are Implemented

By 1960, the Salk injectable polio vaccine (IPV) had been administered to about 98 million American children and adults, and Sabin’s OPV had been administered to about 10,000 Americans and millions in the USSR where the clinical trials had been conducted.[27] It was estimated that 10% to 30% of the vaccines contained live SV40.[28] The federal agency in charge of vaccine licensing and safety at the time was the Division of Biologics Standards (DBS) of the National Institute of Health (NIH).[29] Incredibly, this agency did not order a recall of any of the SV40-contaminated vaccines.[30] The tainted vaccines continued to be administered until 1963 when they were all used and replaced by allegedly SV40-free vaccines as required by the new federal regulations promulgated in 1961.[31]

On March 25, 1961, the federal regulations that controlled the production of oral poliovirus vaccine were amended.[32] These new regulations did not require the vaccine manufacturers to discard their SV40-contaminated poliovirus seeds which were the source for all subsequent polio vaccines.[33] Instead, the rules required that “[e]ach seed virus used in manufacture shall be demonstrated to be free of extraneous microbial agents.”[34]The new regulations also required that each pair of monkey kidneys removed from a monkey for vaccine production “shall be examined microscopically for evidence of cell degeneration.”[35] Furthermore, fluid from the monkey kidney cells had to be combined with other tissue cultures in order to detect if there was any contaminating virus.[36] The regulations required that “[t]he cultures shall be observed for at least 14 days.”[37]

In essence these regulations required an SV40 test that was comprised of taking the monkey kidney cells upon which the vaccine would be grown and: 1) Looking at them through a microscope to see if they demonstrated SV40; 2) Taking fluids from them; 3) Introducing those fluids into other cell cultures; 4) Waiting 14 days; and 5) Seeing whether the other cell cultures were changed as a result of the presence of SV40. These tests werenot designed to detect the contaminating viruses themselves. One cannot see SV40 or any virus with a standard light microscope or the naked eye. Instead, the government’s SV40 test relied on the observation of the presumed effect of an SV40 infection on certain tissue cells to demonstrate the presence of the virus.

On November 8, 1961, after the new regulations were in force, an internal Lederle Laboratories memo stated that three lots of OPV that had been released for clinical trials were probably contaminated with SV40.[38] The memo states, “The decision by Dr. Murray to allow SV40 to be present at the PCB-2 level was the basis for our allowing these lots to pass.”[39] The PCB-2 level comprised one set of fluids taken from the monkey kidney cells and introduced into other cell cultures to detect SV40.[40] It was used to perform the 14-day observation tests for the presence of SV40 and had indicated that these particular polio harvests were SV40 contaminated.[41] “Dr. Murray” referred to above is Dr. Roderick Murray who was the director of the Division of Biologics Standards (DBS) of the National Institute of Health (NIH) from 1955 to 1972.[42] It is unknown why, according to this internal memorandum, the DBS would allow polio vaccines to be released when the very tests designed to find SV40 produced positive results of SV40 infection.

A. The Scientific Rationale for the New Regulations

In 1962, an article received for publication on September 29, 1961, appeared in the Journal of Immunology; entitled, Studies on Simian Virus 40, it was written by scientists from the DBS of the NIH.[43] This article presented the rationale for the new SV40 safety regulations that would remain in place, ostensibly unchanged, for the next four decades.[44] The article’s lead author was Harry M. Meyer, Jr.[45] Dr. Meyer would succeed Dr. Murray as the director of the DBS and would hold this post from 1972 to 1987.[46]

This article discussed some of the challenges with SV40 and polio vaccine production including the fact that the time required for SV40 to show itself in tissue culture tests was “directly related” to the amount of SV40 present.[47] In other words, the testing required by the federal regulations for SV40 detection was dependent on the amount of SV40 present.

The authors also pointed out that it could take up to thirty-five days for SV40 detection when the virus was removed from the blood of an infected monkey.[48] Interestingly, however, the authors also stated that it took only eleven days for low doses of SV40[49] to be detected when it was removed from monkey kidney cells.[50] This was reportedly based on a single experiment. The eleven-day result was significant because the regulations only required fourteen days of observation.[51] If low doses of SV40 could be detected in eleven days then the fourteen-day observation period would be sufficient. A close reading of this article, however, reveals that this crucial study was at best incomplete.

B. A Critique of the Scientific Basis of the New Regulations

The authors of the Journal of Immunology article stated that 10 to 100 TCID₅₀ or “Tissue Culture Infective Dose” of SV40 was detected in eleven days.[52] TCID₅₀ is defined as that dilution of virus required to infect 50% of a given batch of inoculated cell cultures.[53]Therefore, a titer of 10 to 100 TCID₅₀ represents a substantial amount of SV40 because one-half of the cells are infected. In other words, if it took a certain sized dose to infect 50% of the cells in eleven days, it would probably take a substantially smaller dose to infect 1% of the cells in the same period. This smaller dose would then take longer to infect 50% of the cell cultures. Therefore, this article left out the important fact that very low doses of SV40 would most likely not be detected in eleven days.

Second, the government scientists used pure SV40 as a surrogate for SV40-contaminated monkey kidney cells.[54] There is no study that demonstrates the validity of this. During vaccine production, polio seed virus is inoculated into monkey kidney cells in order to grow the vaccine. Samples of these cells are set aside and fluids are drawn off and injected into other cell cultures to test for the presence of SV40. Since these fluids are drawn from monkey kidney cells, they contain a variety of viruses, cellular components, growth medium, and other debris. The sensitivity of the SV40 test for detection of SV40 from this amalgam was the important public health question. The Division of Biologics Standards, however, did not perform this test, or if they did, they did not report their findings. Instead, they used pure SV40 without any other ingredients to determine that eleven days was sufficient.

This flaw in the methodology was demonstrated when the authors discussed the fact that after three weeks of observation, SV40 did not appear from the kidneys of four monkeys that were known to carry SV40 antibodies in their blood. The government scientists stated, “[T]he failure to demonstrate virus in the renal tissue of an appreciable number of rhesus monkeys that had been infected some time earlier was of interest.”[55] This is an admission that even after three weeks of observation (one week longer than the federally mandated two-week observation period) the SV40 from the kidneys of SV40 contaminated monkeys (not pure SV40) did not reveal itself in culture. Unfortunately, the government scientists did not act on this important observation other than to note that it “was of interest.”

Third, the eleven-day finding was apparently based on a single experiment.[56] There is no mention of it being repeated to ensure the accuracy of the results as required by the scientific method.

By 1965, it was well established in the scientific literature that there were several problems with the SV40 tests mandated by the Code of Federal Regulations. First, the fourteen-day SV40 tests were not long enough to detect the virus.[57] In fact, numerous experiments by leading virologists (all non-governmental scientists) found that it took from two to five weeks for the detection of low doses of SV40.[58] Second, there were more sophisticated microbiological tools available that could detect SV40 with greater accuracy.[59] These tests were all widely used and accepted virological techniques. Third, there were several more sophisticated measures available to eliminate SV40 from cultures used to make the poliovirus vaccine.[60] Nonetheless, despite the mounting scientific evidence that the SV40 tests were crude and unreliable, the regulations were not changed and oral polio vaccine manufacturers did not voluntarily adopt any technical improvements to ensure that SV40 was detected and eliminated from their products.

The Flawed Epidemiology

After SV40 was originally detected in the Salk and Sabin vaccines that had been administered to millions of children around the world, the scientific community held its breath and wondered if these children would be stricken with cancer.[61] Indeed, the pediatric cancer rate continued to climb through the 1960’s, 70’s, 80’s and 90’s.[62] But, the few epidemiological studies that looked for a direct link between SV40 and human cancer provided inconsistent conclusions. Some reports found that there was an increased risk of cancer from SV40 exposure[63] and others found that there was no risk.[64] Each of these studies suffered from major flaws including the fact that no one knew who actually received the SV40-contaminated vaccines and who did not, so it was impossible to compare an SV40-exposed group with a non-exposed group.[65]

SV40—A Human Carcinogen

By 1999, numerous pathologists, microbiologists, and virologists throughout the world had detected SV40 in a variety of human cancers such as brain tumors[66] including medulloblastomas,[67] bone cancers,[68] and mesotheliomas[69] a fatal lung cancer. These were the very same cancers that were created when SV40 was introduced into animals.[70]The advent of Polymerase Chain Reaction (PCR) technology that could identify the genetic code of specific strands of DNA demonstrated with precision that it was this monkey virus that was being detected in human cancers and no other.[71] Moreover, the rates of these particular cancers had steadily increased over the last few decades.[72] The question that had been left unanswered for almost four decades now faced scientists again—was SV40 responsible for causing or contributing to human cancers?

Over the last forty years since its discovery, SV40 had become one of the most widely studied and best understood viruses in microbiology.[73] It was routinely used to create human cancers in the laboratory in order to test cancer therapies.[74] In addition, it is now known how this virus caused cancer on a molecular level. After careful study documented in peer reviewed publications, leaders in SV40 research announced that SV40 was a class 2A human carcinogen.[75]

The Government’s Response

Nonetheless, the various United States government agencies such as the Centers for Disease Control (CDC) and National Cancer Institute (NCI) disputed these conclusions. According to the CDC, “SV40 virus has been found in certain types of cancer in humans, but it has not been determined that SV40 causes these cancers.”[76] According to the National Intsitutes of Health (NIH), “the NCI is continuing to evaluate the possible link between SV40 infection and human cancers.”[77] A question has been raised whether this continuing evaluation is being performed with complete scientific integrity. One article written by an attorney and published in a peer reviewed scientific journal describes how the NCI deliberately compromised a study that would have demonstrated the association between SV40 and mesothelioma.[78]

While the United States government continues to evaluate whether or not SV40 represents a public health threat and whether SV40 is a human carcinogen, several scientists at the NCI concluded that SV40 contributed to the formation of mesotheliomas.[79] In fact, the federal government has licensed technology to target SV40 in the treatment of human mesotheliomas.[80]

SV40 and the Public Health

Despite the government’s foot dragging, in the last several years, scientists from around the world have made startling and disturbing discoveries. They have found SV40 antibodies in a significant percentage of people including children who were too young to receive the SV40 contaminated vaccines of the early 1960’s.[81] They have also discovered that cancers with SV40 are less likely to be responsive to chemotherapy and radiation because SV40 interferes with the genes necessary for cancer cells to die when they are exposed to chemo or radiation therapy.[82]

The Institute of Medicine Report

In July 2002, the National Academy of Science Institute of Medicine (IOM) Immunization Safety Committee convened a study into SV40 and cancer which culminated in a report published in October 2002. According to the IOM report “SV40 Contamination of Polio Vaccine and Cancer”:

The committee concludes that the biological evidence is strong that SV40 is a transforming [i.e., cancer-causing] virus, . . . that the biological evidence is of moderate strength that SV40 exposure could lead to cancer in humans under natural conditions, [and] that the biological evidence is of moderate strength that SV40 exposure from the polio vaccine is related to SV40 infection in humans.[83]