Polio Virus

Context

• The West Bengal government announced the introduction of an additional dose of injectable polio vaccine as part of the Universal Immunisation Programme (UIP) for children.

About

• The additional dose of Inactivated Poliovirus (IPV) at nine months will protect against any polio, like Vaccine Associated Paralytic Polio or Vaccine Derived Polioviruses.
• As of October 2022, the WHO said only Afghanistan and Pakistan remain with the indigenous transmission of wild poliovirus type 1 (WPV1) worldwide. 
• Wild poliovirus cases have decreased by over 99% since 1988, from an estimated 350 000 cases in more than 125 endemic countries to 6 reported cases in 2021.
• WHO on 24th February 2012 removed India from the list of “endemic countries with active poliovirus transmission”

• Recently genetic variants of vaccine poliovirus type 2 were detected in wastewater in Jerusalem, London, and New York in early 2022.

What is Polio Virus?

• Poliomyelitis, also known as polio, is an infection caused by a virus (poliovirus). It is a serious, highly contagious disease that can affect a person’s nervous system.
• There are three types of wild poliovirus:
  • WPV 1: still exists but efforts are going on to eradicate it.
  • WPV 2: eradicated.
  • WPV 3: eradicated.
• Polio typically affects children aged 5 years or younger. It can result in muscle weakness, permanent disability, and even death.
• One in 200 infections leads to irreversible paralysis. Among those paralysed, 5–10% die when their breathing muscles become immobilized.
• There is no cure for polio, but there are safe, effective vaccines that, given multiple times, protect a child for life.
• As an unintended consequence, type 2 vaccine virus variants (circulating vaccine-derived polioviruses) that mimic wild viruses’ contagiousness and neurovirulence, have been emerging and spreading.

Efforts to Eradicate

• In 1988, the World Health Assembly adopted a resolution for the worldwide eradication of polio, marking the launch of the Global Polio Eradication Initiative (GPEI).

• In 1986 India was provided with a $2.6 million grant for a pilot polio vaccination campaign under the Polio eradication campaign, Polio Plus.
• India committed to the resolution passed by the World Health Assembly for global polio eradication in 1988.
• National Immunization nDay (NID) commonly known as the Pulse Polio Immunization programme was launched in India in 1995 and is conducted twice in the early part of each year.
• Additionally, multiple rounds (at least two) of sub-national immunization day (SNID) have been conducted over the years in high-risk states.
• South-East Asia Region of WHO including India has been certified polio-free by “The Regional Certification Commission (RCC)” on 27th March 2014. 

What is the need for an extra dose?

• The additional dose is being given besides the existing oral and injectible polio doses that have been part of the UIP.
• The oral polio vaccine, which is made from a live virus, has the possibility of leaving the virus in the environment, which can then infect someone.
• The injectable polio vaccine, which is made from an inactivated virus, does not leave this possibility. Besides, the absorption of the injectable vaccine is better.
• The third dose will give enhanced protection against the disease and will be given when the child turns nine months.

Way Forward

• As long as a single child remains infected, children in all countries are at risk of contracting polio. Failure to eradicate polio from these last remaining strongholds could result in a global resurgence of the disease.
• The Polio Eradication Strategy 2022–2026 lays out the roadmap to securing a lasting and sustained world, free of all polioviruses, and transition and post-certification efforts are ongoing to assure that the infrastructure built up to eradicate polio will continue to benefit broader public health efforts, long after the disease is gone. 

Source: The Hindu