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Polio vaccine: the story on HearLore | HearLore
Polio vaccine
In the autumn of 1935, a scientific symposium in Milwaukee descended into chaos as one of the most respected researchers in the field was publicly accused of being a murderer. John A. Kolmer, a physician from Philadelphia, had developed a live polio vaccine that he administered to hundreds of children, only for several of them to develop paralysis and some to die. The accusations were so severe that Kolmer, who had previously tested the vaccine on himself and his own children, simply wished the floor would open up and swallow him. This catastrophic failure halted all vaccine development for nearly two decades, leaving the world vulnerable to epidemics that would kill thousands of children annually. The tragedy was compounded by the fact that Kolmer's colleague, Maurice Brodie, had developed a safer inactivated vaccine using formaldehyde, but the scientific community of the time dismissed it as ineffective because it did not produce the humoral immunity that was the prevailing theory of the day. Brodie, who had worked tirelessly to prove his method, was fired from his position and died of a heart attack at the age of 36, never seeing his life's work vindicated. The era was defined by amateurish methods, such as grinding spinal cords of infected monkeys and soaking them in salt solutions, creating what critics called a veritable witches brew that lacked the oversight and safety protocols required for human trials.
The Breakthrough in Cell Culture
The path to a safe vaccine was blocked until 1948, when a team at Children's Hospital Boston achieved a feat that seemed impossible to their peers. John Enders, Thomas Weller, and Frederick Robbins successfully cultivated the poliovirus in human tissue outside of the body, a discovery that earned them the Nobel Prize in Physiology or Medicine in 1954. Before this breakthrough, researchers were forced to rely on monkey spinal cords, a process that was not only dangerous but also inconsistent. The ability to grow the virus in human cells allowed for the precise study of the virus and the development of vaccines that could be produced in large quantities. This scientific leap paved the way for Jonas Salk, who began his work at the University of Pittsburgh in 1952. Salk's team, including Julius Youngner and Byron Bennett, developed an inactivated polio vaccine that used formaldehyde to kill the virus, rendering it harmless while still stimulating the immune system. The first successful test of Salk's vaccine was announced on the 26th of March 1953, when he reported on CBS radio that a small group of adults and children had been successfully vaccinated. The world was on the brink of a miracle, but the road to mass production was fraught with peril and political intrigue.
Who developed the first live polio vaccine that caused paralysis and deaths in 1935?
John A. Kolmer developed the live polio vaccine that caused paralysis and deaths in the autumn of 1935. This catastrophic failure halted all vaccine development for nearly two decades.
When did John Enders Thomas Weller and Frederick Robbins successfully cultivate the poliovirus in human tissue?
John Enders Thomas Weller and Frederick Robbins successfully cultivated the poliovirus in human tissue outside of the body in 1948. This discovery earned them the Nobel Prize in Physiology or Medicine in 1954.
What happened on the 12th of April 1955 regarding the Salk vaccine and Cutter Laboratories?
The Salk vaccine was announced as safe and effective on the 12th of April 1955. Just a week later reports emerged that the Cutter Laboratories vaccine had not been properly inactivated leading to 260 cases of polio and 11 deaths.
How many Americans received polio vaccine contaminated with SV40 between 1955 and 1963?
Over 98 million Americans received one or more doses of polio vaccine that were contaminated with SV40 between 1955 and 1963. Subsequent large-scale studies found no increased incidence of cancer in persons who had received the contaminated vaccine.
When was the global effort to eradicate polio launched by the World Health Organization and UNICEF?
The World Health Organization UNICEF and the Rotary Foundation launched a global effort to eradicate polio in 1988. This campaign reduced the number of reported polio cases from an estimated 350,000 in 1988 to just 33 in 2018.
When was the novel oral polio vaccine type 2 granted full licensure?
The novel oral polio vaccine type 2 was granted emergency licensing in 2021 and full licensure in December 2023. This genetically modified vaccine has greater genetic stability than the traditional oral vaccine and is less likely to revert to a virulent form.
On the 12th of April 1955, the tenth anniversary of the death of President Franklin D. Roosevelt, the world celebrated the announcement that the Salk vaccine was safe and effective. The Francis Field Trial, the largest medical experiment in history, had involved 1.8 million children and showed that the vaccine was over 90% effective against two of the three poliovirus types. However, just a week later, the Surgeon General received reports of children who had contracted polio shortly after being vaccinated with the Salk vaccine produced by the Cutter Laboratories. Investigations revealed that the Cutter vaccine had not been properly inactivated, allowing live poliovirus to enter more than 100,000 doses. The result was 260 cases of polio and 11 deaths, a tragedy that shattered public confidence in the vaccine. The incident led to the immediate withdrawal of all Cutter vaccines from the market and the establishment of a Technical Committee on Poliomyelitis Vaccine to ensure the safety of future doses. The Cutter incident highlighted the dangers of rushing mass production and the critical importance of quality control in vaccine manufacturing. Despite the setback, the Salk vaccine remained the primary tool for fighting polio, and by 1961, the number of polio cases in the United States had dropped to just 161.
The Oral Revolution and the Soviet Gambit
While the Salk vaccine was being distributed, Albert Sabin was developing a different approach that would eventually change the course of global eradication efforts. Sabin's oral polio vaccine used a live attenuated virus that was administered by mouth, eliminating the need for sterile syringes and needles. This made it ideal for mass vaccination campaigns, especially in developing countries. Sabin's vaccine was first tested in Mexico and the Soviet Union, where it was used to vaccinate ten million children in 1959. The Soviet Union, under the leadership of Mikhail Chumakov, played a crucial role in the development and testing of the Sabin vaccine, providing the large-scale trials that were necessary to prove its safety and efficacy. The Sabin vaccine was licensed for commercial use in 1961 and quickly supplanted the Salk vaccine in many parts of the world. The oral vaccine provided longer-lasting immunity and was easier to administer, making it the preferred choice for global eradication initiatives. However, the live virus in the Sabin vaccine carried a small risk of causing vaccine-associated paralytic poliomyelitis, a side effect that would become a major concern in the decades to follow.
The Shadow of SV40 and Cancer
In 1960, a hidden danger was discovered in the polio vaccines that had been distributed to millions of Americans. The rhesus monkey kidney cells used to prepare the inactivated polio vaccine were found to be infected with the simian virus-40, or SV40. This virus, which was naturally occurring in monkeys, was inadvertently introduced into the vaccine during the manufacturing process. Between 1955 and 1963, over 98 million Americans received one or more doses of polio vaccine that were contaminated with SV40. The discovery of SV40 raised fears that it might cause cancer in humans, as it had been found to cause tumors in rodents. However, subsequent large-scale studies, including one by the National Cancer Institute and another in Sweden, found no increased incidence of cancer in persons who had received the contaminated vaccine. The controversy over SV40 remains unresolved, with some researchers continuing to investigate the potential link between the virus and certain forms of cancer in humans. The SV40 incident serves as a reminder of the complexities and risks involved in vaccine development and the importance of ongoing monitoring and research.
The Global Eradication Campaign
In 1988, the World Health Organization, UNICEF, and the Rotary Foundation launched a global effort to eradicate polio, relying largely on the oral polio vaccine developed by Albert Sabin and Mikhail Chumakov. The campaign has been remarkably successful, reducing the number of reported polio cases from an estimated 350,000 in 1988 to just 33 in 2018. Polio was eliminated in the Americas by 1994, and Europe was declared polio-free in 2002. India, once a major stronghold of the disease, was declared polio-free in 2014. Despite these successes, the eradication effort faces ongoing challenges, including the emergence of circulating vaccine-derived poliovirus, a form of the vaccine virus that has reverted to causing poliomyelitis. In 2017, for the first time, more cases of circulating vaccine-derived poliovirus were recorded than wild poliovirus. The campaign has also faced resistance in some regions, particularly in Pakistan and Afghanistan, where misinformation and conspiracy theories have led to attacks on vaccination teams. The global effort to eradicate polio continues to be a testament to the power of international cooperation and the importance of vaccination in protecting public health.
The Modern Vaccine and Future Challenges
In recent years, the polio eradication effort has faced new challenges that have required the development of novel vaccines. The emergence of circulating vaccine-derived poliovirus type 2, which increased from two cases in 2016 to 1,037 cases in 2020, has led to the development of a novel oral polio vaccine type 2, or nOPV2. This genetically modified vaccine has been granted emergency licensing in 2021 and full licensure in December 2023, with the aim of making the vaccine safer and stopping further outbreaks. The nOPV2 vaccine has greater genetic stability than the traditional oral vaccine and is less likely to revert to a virulent form. The development of genetically stabilized vaccines targeting poliovirus types 1 and 3 is also in progress, with the intention that these will eventually completely replace the Sabin vaccines. The global community continues to face the challenge of maintaining high vaccination coverage and preventing the importation of wild poliovirus into previously polio-free regions. The fight against polio is far from over, but the progress made since the first successful vaccine was developed in 1952 is a testament to the resilience and ingenuity of the scientific community.