Recently, The West Bengal government announced that it was introducing an additional dose of injectable polio vaccine as part of the Universal Immunization Programme (UIP) for children.
- An additional dose of inactivated poliovirus (IPV) at nine months will protect against any polio thereafter — Vaccine Associated Paralytic Polio or Vaccine Derived Polioviruses
What is Polio?
- It can invade the central nervous system and as it multiplies, destroy the nerve cells that activate muscles, causing irreversible paralysis in hours.
- Polio typically affects children aged 5 years or younger.
- It can result in muscle weakness, permanent disability, and even death.
- According to the India Polio Learning Exchange (along with UNICEF): Of those paralysed: 5-10% die when their breathing muscles become immobilised.
- Three types of wild poliovirus (WPV): Type 1, Type 2, and Type 3.
- Type 2 Wild Poliovirus: It was declared eradicated in September 2015.
- The last detection was in India, 1999.
- Type 3 Wild Poliovirus: It was declared eradicated in October 2019. It was last detected in November 2012.
- Only type 1 wild poliovirus remains.
- No Cure But Vaccines: There is no cure for polio, but there are safe, effective vaccines which, given multiple times, protect a child for life.
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Polio Vaccines
- Jonas Salk developed the first polio vaccine.
- Inactivated poliovirus vaccine
- IPV protects people against all three types of poliovirus.
- IPV does not contain live virus and cannot cause disease.
- It protects people from polio disease but does not stop transmission of the virus.
Salk made the first successful vaccine for polio.
- Major Block: Earlier, The inability to culture polio in non-nerve cells was a major roadblock to developing a polio vaccine.
- Later, Enders and his team: They developed a method that made poliovirus could now be mass-produced for vaccine research.
- Salk Development: He inactivated the virus by treating it with formaldehyde, and injected it into his test subjects.
- The fragments of the inactivated virus were able to induce immunity in their bodies.
- Systemic immunity : Importantly, since the vaccine was introduced into the muscle, it generated systemic immunity.
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- Oral polio vaccine
- Albert Sabin Developed Another vaccine: It contained live polio strains weakened by growing them serially in macaque cells, making them unfit for human infection.
- It contained live virus particles, it had to rely on its natural mode of infection and was therefore administered orally. This was the oral polio vaccine (OPV).
- Vaccine-derived polioviruses (VDPVs): In rare instances, the vaccine-virus may be able to circulate over time and mutate in communities with insufficient immunity or immunocompromised individuals.
- These mutated OPV strains can cause polio disease. They are called poliovirus variants or vaccine-derived polioviruses (VDPVs).
Eradication target missed
- WHO’s Global Polio Eradication Initiative is thus set to miss its deadline of eradicating polio by the end of 2024.
- Since Africa was declared polio-free in August 2020: The wild poliovirus has been restricted to rural pockets in Afghanistan and Pakistan.
- Reappear: According to a recent report in Science, the virus is beginning to reappear in big cities in these two countries.
- Reason for Reemergence: It is a result of vaccine hesitancy due to misinformation, conflict, poverty, and limited access to these isolated regions.
- It also recorded that so far, 33 countries have outbreaks of variant polioviruses, such as in the U.K., the U.S., Israel and Malawi.
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Polio Status in India
- In 1995: India launched the Pulse Polio Immunization Programme in 1995 brought down polio cases from 50,000-100,000 each year in the 80s to zero in 2012.
- In 2012: the WHO removed India from the list of endemic countries
- In January 2014: India was declared polio-free after three years of zero cases.
- 27th March 2014: South-East Asia Region of WHO including India has been certified polio-free by “The Regional Certification Commission (RCC)”
- India introduced the injectable polio vaccine in the Universal Immunization Programme to reduce chances of Vaccine Derived Polio Virus (VDPV), which continues to happen in the country.
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Global Polio Eradication Initiative (GPEI)
- Public-private partnership to eradicate polio worldwide
- The goal of the GPEI is to complete the eradication and containment of all wild, vaccine-related, and Sabin polioviruses, so no child suffers from paralytic poliomyelitis ever again.
- It has five partners, the WHO, Rotary International, the US Centers for Disease Control and Prevention, UNICEF, Bill & Melinda Gates Foundation and GAVI, the vaccine alliance.
- GPEI’s four pillars include Routine Immunization, Supplementary immunization, Surveillance, and Targeted mop-up campaigns.
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July 3, 2024