The World Health Organization (WHO) reports environmental samples and cases of wild poliovirus (WPV) and vaccine-derived poliovirus (VDPV).

Recent findings on Polio

• Polio Detected in Europe: Routine wastewater surveillance has detected the presence of poliovirus in five European countries, Finland, Germany, Poland, Spain, and the United Kingdom, since September 2024.
• Confirmed Polio Case in Gaza: A 10-month-old child in Gaza was confirmed to have polio, highlighting the ongoing local risks associated with the disease.
• Africa: Cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) have been reported in Cameroon, Côte d’Ivoire, Chad, and Nigeria.
• Asia: Pakistan has reported cases of wild poliovirus type 1 (WPV1) and circulating VDPV2.
• Ongoing Vigilance and Immunization Efforts: The World Health Organization (WHO) underscores the importance of robust disease surveillance and widespread vaccination campaigns.
  • Despite national immunization coverage rates of 85–95%, subnational gaps in immunity remain, requiring focused and targeted interventions.

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About Poliomyelitis (Polio)

• Poliomyelitis is a highly infectious viral disease primarily affecting children under five years of age.
• Transmission: It spreads mainly through person-to-person contact via the faecal-oral route or, less commonly, through contaminated water or food.
  • Recent research suggests respiratory transmission plays a significant role.
  • Shedding of poliovirus in the throat supports the theory of respiratory transmission, akin to other contagious childhood diseases like measles and pertussis.
• Impact: The virus multiplies in the intestine and can invade the nervous system, causing paralysis.
• Wild Poliovirus Strain Status Worldwide
  • Type 1: Remains endemic in Pakistan and Afghanistan as of 2022.
  • Type 2: Declared eradicated in 1999.
  • Type 3: Declared eradicated in 2020.
• India achieved a polio-free status in 2014 by WHO , with the last reported wild poliovirus case in 2011.

Vaccine-Derived Polio

• Vaccine Composition: The Oral Polio Vaccine (OPV) contains a weakened form of the poliovirus, which induces an immune response.
• Circulating Vaccine-Derived Poliovirus (cVDPV): In under-immunized populations, the excreted vaccine virus can circulate, undergo genetic changes, and revert to a form capable of causing paralysis.
• Prevention: To stop the transmission of cVDPV, WHO recommends conducting multiple rounds of high-quality immunization campaigns.

Characteristics of Polio Vaccines

Efforts to Eradicate Polio

Global Initiatives

• The Global Polio Eradication Initiative (GPEI) aims to eradicate all wild, vaccine-related, and Sabin polioviruses to ensure no child suffers from paralytic poliomyelitis again.
• The GPEI’s four pillars include routine immunization, supplementary immunization, surveillance, and targeted mop-up campaigns.

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India’s Approach

• Annual Polio Campaigns: National Immunization Days (NID) and Sub-National Immunization Days (SNID) are conducted annually to maintain high immunity levels and ensure no child is left unvaccinated.
• Surveillance and Border Vaccination: Vaccination efforts continue at international borders to reduce the risk of polio re-importation from endemic regions.
• Inactivated Polio Vaccine (IPV): Introduced in 2015, IPV offers additional protection against polio, particularly against type 2 poliovirus.
• Mission Indradhanush: Launched in 2014, this initiative aims to achieve 90% immunization coverage, focusing on hard-to-reach areas with low vaccination rates.
• Additional Dose of Polio Vaccine:  An additional dose of polio vaccine is now being administered alongside the oral and injectable polio doses that are part of the Universal Immunization Programme (UIP).This third dose, introduced to provide enhanced protection against polio, will be given when a child turns nine months old.

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