A two-year-old child in Meghalaya has been confirmed to have polio, raising concerns as India was declared polio-free by WHO in 2014. WHO is looking into the vaccine-derived infection cases
As the world, including India, grapples with rising Mpox cases, the reports of a two-year-old Meghalayan child testing positive for polio, a highly contagious viral disease that can even result in fatal paralysis, is worrying the authorities. However, the health ministry officials said the case was vaccine-derived and there was no cause for concern.
Even though this case does not put India’s polio-free status in jeopardy, the West Garo Hills region where it was discovered is on high alert to prevent the infection from spreading.
What is vaccine-derived polio infection?
A strain that is related to the virus’s weaker form and is used in the oral polio drops for vaccination is called a vaccine-derived poliovirus. Despite the fact that the vaccine is safe and has helped the majority of nations successfully eradicate the infection, it can, in very rare cases, trigger the disease in children who don’t have a strong immune system.
The vaccine virus can get excreted while triggering an immune response in the body, and undergo genetic changes over time, in the bloodstream.
Dr T Jacob John, former professor of virology at Christian Medical College Vellore stated that, “The oral polio vaccine can lead to vaccine-derived polio strains in two ways. One, the weakened virus can continue circulating from child to child, gaining back its ability to transmit quickly and cause severe infection every time it spreads. Two, the vaccine virus can cause chronic infection in children with weakened immune systems, replicating in their gut for years and slowly gaining its ability to cause severe infection. In the Meghalaya case, it seems like the virus replicated within one child. It is easier to control further spread of such vaccine-derived variants because the other children in the area are likely fully immunised”.
He further added, “One in every 150,000 children given the vaccine in India gets the infection from it.” Therefore, even if all children in the area have been fully immunised, health professionals would still need to re-immune them as a preventative measure.
Has India previously seen cases of polio caused by vaccines?
In 2011, the Howrah district of West Bengal was the location of the nation’s recent wild poliovirus infection. In 2014, the nation was declared polio-free after successfully preventing any wild polio infections. However, cases of polio caused by the vaccine have been reported during this time.
In 2013, a child with immuno-deficiency who was 11 months old and lived in the Beed district of Maharashtra died of vaccine-derived polio. It was also reported in a child from Delhi who was 2.5 years old. In 2022, polio virus derived from vaccines was found in sewage samples in Kolkata. In India, these aren’t the only cases of polio caused by the vaccine.
Unless cases of wild poliovirus infection are identified, India will continue to be a polio-free nation.
Worldwide cases of Polio
There have been 72 confirmed cases of vaccine-derived poliovirus cases in 2024, with 68 type 2 infections and four type 1 infections, according to WHO data. 30 (42%) of the 72 cases in 2024 took place in Nigeria. The vaccine-derived poliovirus has been found in the environment in Equatorial Guinea, Gambia, Liberia, Algeria, Cote d’Ivoire, Egypt, Mozambique, Senegal, Sierra Leone, Sudan, Uganda, and Zimbabwe but no cases have been reported there.
In 2023, there were 527 confirmed cases of vaccine-derived polio, 393 of which were type 2 infections and 134 of type 1. In 2023, 224 (43%) of the 527 vaccine-related cases reported occurred in the Democratic Republic of the Congo.
Government response and concerns over Polio in India
Meghalaya Chief Minister Conrad K Sangma has focused on the gravity of the condition, mentioning that the government is carefully reviewing the case prior to issuing an official statement and planning an action. “We need to be very careful. The government is still determining the specifics of the case, and we will come up with an official statement and plan of action shortly,” Sangma stated.
One of the clusters in which the suspected case was found has a significant number of unvaccinated residents, highlighting the significance of ongoing surveillance and vaccination efforts.