Madison Clarke
The US has not stopped manufacturing the polio vaccine, but it did stop using the oral poliovirus vaccine (OPV) in 2000. OPV contains a live, weakened poliovirus, and in extremely rare cases, it can mutate into a form capable of causing disease. The Advisory Committee for Immunization Practices recommended that children in the US be immunized with the inactivated poliovirus vaccine (IPV), which contains a dead virus that cannot reproduce and cause disease. This change in policy was due to the epidemiology of the disease and the economics of vaccine production.
| Characteristics | Values |
|---|---|
| Reason for stopping OPV vaccine | In rare cases, the weakened virus in the OPV vaccine has mutated into a form capable of causing disease |
| Year of discontinuation of OPV vaccine | 2000 |
| Current polio vaccine in the US | Inactivated poliovirus vaccine (IPV) |
| Number of doses of IPV vaccine | 4 doses |
| Age of administration of IPV vaccine | 2 months, 4 months, 6 to 18 months, and 4 to 6 years |
| Percentage of immunity after 2 doses of IPV vaccine | Around 90% |
| Percentage of immunity after 3 doses of IPV vaccine | At least 99% |
| Groups recommended for IPV vaccine by CDC | People travelling to high-risk countries, lab workers exposed to poliovirus samples, and healthcare workers treating potential polio patients |
| Year of first polio vaccine availability in the US | 1955 |
| Year of first successful demonstration of a polio vaccine | 1950 |
| Developer of first successful polio vaccine | Hilary Koprowski |
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What You'll Learn
The Cutter Incident
On April 12, 1955, the success of the polio vaccine trial was announced, and Cutter Laboratories and other companies began distributing the vaccine. However, within two weeks, the surgeon general received reports that seven children had become paralyzed following inoculation, with most having received the vaccine from Cutter Laboratories. The surgeon general suspended all vaccinations.
Subsequent investigations revealed that Cutter's vaccine had been ineffective in inactivating the live virus, resulting in more than 200,000 people being infected with the live polio virus. This included 100,000 contacts of immunized children, with 70,000 developing muscle weakness, 164 suffering severe paralysis, and 10 dying. The exposures led to a further 113 people being paralyzed and five deaths, causing a brief halt to the entire US vaccination program and affecting public trust in vaccines.
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The development of the IPV vaccine
The development of the polio vaccine is a long and complex story involving many researchers and scientists. The first formal presentation of a polio vaccine came in November 1935 when Kolmer presented the results of 446 children and adults vaccinated with his attenuated vaccine. However, he did not provide instructions on how to administer the vaccine or report side effects, and over 10 cases of paralytic polio were reported following vaccination.
In 1950, Hilary Koprowski successfully demonstrated a live attenuated polio vaccine that people drank. However, it was not approved for use in the United States. In 1955, Jonas Salk announced the success of the inactivated polio vaccine (IPV), which consisted of inactivated poliovirus strains of all three poliovirus types. This vaccine was given by intramuscular or intradermal injection and needed to be administered by a trained health worker. IPV induces excellent protective immune responses in most people, with over 90% of individuals developing protective antibodies to all three serotypes of poliovirus after two doses.
Another attenuated live oral polio vaccine (OPV) was developed by Albert Sabin and came into commercial use in 1961. OPV was easier to administer than IPV and provided longer-lasting immunity. It was also cheaper and could be used to interrupt the transmission of the virus, making it a powerful tool for stopping polio outbreaks. However, OPV carried a small risk of vaccine-derived polio, and in the 1990s, many developed countries replaced OPV with IPV.
The development of the polio vaccine involved numerous researchers and scientists, including Brodie, whose work laid the foundation for the Salk vaccine, and Sabin and Koprowski, who conducted their testing outside the United States due to the commitment to the Salk vaccine in America. The emergence of circulating vaccine-derived poliovirus (cVDPV) has led to the development of novel oral polio vaccines, such as nOPV2, which aim to make the vaccine safer and stop further outbreaks.
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The OPV vaccine is no longer used in the US
The oral poliovirus vaccine (OPV) is no longer used in the US. The OPV uses a live, weakened form of the poliovirus, which is highly effective at protecting against the disease. The weakened virus is created by growing it in monkey kidney cells, which alters the virus so that it does not infect human cells as efficiently. When the vaccine is ingested, the virus replicates in the intestines, causing antibodies to be made there. This prevents the infection from progressing to the bloodstream, where it can cause paralysis.
However, in rare cases, the weakened virus in the OPV vaccine can mutate into a form capable of causing disease. This mutation can cause vaccine-associated paralytic polio (VAPP), which can continue to spread. These types of polioviruses are called "vaccine-derived poliovirus" (VDPV). Due to this risk, US health authorities switched to using only the inactivated poliovirus vaccine (IPV) in 2000.
The IPV vaccine, which is the only one used in the US, provides around 90% immunity against all three types of poliovirus after two doses and at least 99% immunity after three doses. IPV is given as a series of four shots at 2 months, 4 months, 6 to 18 months, and again at 4 to 6 years of age. The dead virus in the IPV vaccine cannot reproduce, so it cannot revert to natural polio or cause paralysis. While IPV does not provide the same level of immunity in the intestines as OPV, it does prevent the virus from spreading to the bloodstream, brain, or spinal cord.
The decision to switch from OPV to IPV in the US was also influenced by the epidemiology of the disease and the economics of vaccine production. While OPV was used almost exclusively in the US for 35 years, the switch to IPV was made to ensure the safety and effectiveness of the polio vaccine.
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The success of vaccination in eradicating polio
The first successful polio vaccine was created by US physician Jonas Salk in the early 1950s. Salk's inactivated polio vaccine (IPV), announced and licensed on April 12, 1955, was a groundbreaking achievement. This was followed by Albert Sabin's oral polio vaccine (OPV), which came into commercial use in 1961 and was licensed in most industrialized countries by 1962. OPV has been instrumental in interrupting the transmission chain of the poliovirus, making it a powerful tool to stop outbreaks.
The ease of administering OPV orally made it ideal for mass vaccination campaigns. Czechoslovakia became the first country to scientifically demonstrate the nationwide eradication of poliomyelitis in 1960, shortly after adopting OPV. Cuba's nationwide immunization programs with OPV in 1962 further highlighted the vaccine's effectiveness. These successes suggested that polioviruses could be eradicated globally.
The Pan American Health Organization (PAHO), under Ciro de Quadros' leadership, launched an initiative to eradicate polio from the Americas in 1985. This effort, complemented by Rotary International's work, resulted in the Americas being declared polio-free by 1994. By 2000, the Western Pacific had also eliminated polio.
While great strides have been made, challenges remain. As of 2025, Afghanistan and Pakistan are the only countries where wild poliovirus is still endemic. Ongoing conflicts and low immunization rates in these regions pose significant obstacles to achieving global polio eradication. Additionally, maintaining the potency of vaccines in extremely hot or remote areas has been challenging.
To overcome these hurdles, global collaboration and innovative solutions are essential. The development of novel oral polio vaccines, such as nOPV2, aims to enhance vaccine safety and prevent further outbreaks of circulating vaccine-derived poliovirus (cVDPV). The success of vaccination in eradicating polio has been significant, and ongoing efforts are crucial to ensuring that no child suffers from this devastating disease.
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The role of litigation in vaccine development
The development of vaccines has been critical in the fight against infectious diseases, with the polio vaccine being a notable example. The first successful demonstration of a polio vaccine was in 1950 by Hilary Koprowski, using a live attenuated virus. However, the emergence of circulating vaccine-derived poliovirus (cVDPV) has led to the development of novel oral polio vaccines to improve safety and prevent further outbreaks.
The history of polio vaccine development in the United States is marked by incidents like the Cutter Incident in 1955, where a defective polio vaccine caused thousands of cases of polio and led to the first mass vaccination program's abandonment. This incident resulted in litigation and highlighted the need for effective federal regulation of vaccines. Subsequently, the National Vaccine Injury Compensation Program was introduced in 1986 to protect manufacturers from litigation and ensure the continued production of vaccines.
Litigation plays a significant role in vaccine development, influencing both the legal and public health landscapes. On the one hand, it provides recourse for those adversely affected by vaccines and ensures the maintenance of industrial and professional standards. The National Childhood Vaccine Injury Act of 1986 aimed to balance vaccine development and public health considerations with the need for legal protections and compensation for those impacted by vaccine-related injuries.
However, the threat of litigation can also deter innovation and the introduction of new vaccines. The contemporary climate of risk aversion and predatory litigation has made vaccine manufacturers vulnerable to lawsuits, potentially hindering progress in vaccine development and public health. This challenge has been observed in the case of Robert F. Kennedy Jr., who organized mass litigation against Merck over its Gardasil vaccine, leveraging his position as U.S. Health and Human Services Secretary to influence public opinion and build a case against the pharmaceutical industry.
To strike a balance, some propose removing the option of suing vaccine manufacturers and limiting compensation to official programs. This approach aims to protect vaccine development and public health while still providing recourse for those adversely affected by vaccines. Overall, litigation plays a complex role in vaccine development, influencing public health policies, industrial standards, and the pace of innovation in the field.
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Frequently asked questions
No, the US has not stopped manufacturing the polio vaccine. However, the oral poliovirus vaccine (OPV) was discontinued in 2000 due to rare cases of the weakened virus in the vaccine mutating into a harmful form. The US now exclusively uses the inactivated poliovirus vaccine (IPV), which is given as a series of shots and provides 90% immunity against all three types of poliovirus after two doses and at least 99% immunity after three doses.
The OPV vaccine contains a live, weakened form of the poliovirus, which can replicate in the intestines of vaccinated individuals and cause them to shed the virus. While this approach can provide contact immunity to others, it also carries a small risk of the weakened virus reverting to its original wildtype form, causing vaccine-associated paralytic polio (VAPP).
Polio has been eradicated across most of the world, including the United States, due to widespread vaccination efforts. However, sporadic cases can still occur, and the disease is endemic in some parts of the world, such as Afghanistan and Pakistan. While there is no federal law mandating the polio vaccine, all 50 states and the District of Columbia have state laws requiring children to be vaccinated.
