What happens when a country with a sizeable population below 15 years of age ,basking in glory of having eliminated the malady of Poilomyelitis since March 2014 ,gets a jolt after its surveillance mechanism detects the globally eradicated Poliovirus 2 strain in a batch of vaccines manufactured by a Ghaziabad company ,which is one of the four domestic suppliers of Poliovaccine to India ? In September 2015, the WHO had declared type-2 polio to be fully eradicated. On WHO’s advice, India phased out the type-2 virus from its oral vaccines in April 2016 to ensure that the threat of vaccine-derived polio was mitigated.
Kudos to the sensitive Polio surveillance system in India which detected the timely contamination. We need to be aware that there is an inbuilt strict environmental surveillance mechanism for Polio where sewage samples are collected form 45 sites across 8 Indian states for testing, along with samples from Children under 15 years reporting with symptoms of Acute Flaccid paralysis .In September sewage samples from Allahabad tested positive for Type 2 virus ,the eradicated strain and which is not included in the current bivalent OPV ,sending tremors across the Public health sector.Experts suggest this as more of an adulteration than contamination as the trivalent vaccine used earlier had Type 2 component .
Public response to the scare :
• Message goes viral on social media ,calling for parents to refrain from administering OPV to their kids.
• This public health scare has the potential to affect thousands of children necessitating immediate damage control measures .

Experts Pacify the public:

Public health experts ,Ministry officials ,Epidemiologists joined hands to pacify the public .To quote Dr.NK Arora, chairman of the National Certification Committee for Polio Eradication, “Our children are protected by injectable polio vaccine too. The type-2 virus is the weakest of the three and this is not a health risk for our children, neither does it derail India’s polio programme,”

What is WHO’s take on the incident ?
WHO played down the risk to Indian children from the adulterated Polio vaccine . According to Shamila Sharma, WHO SEARO spokesperson ,risk to children was “minimal” due to the high routine polio immunization coverage in India. The WHO funds and supports India’s polio-control program.
Here’s what Polio researcher Dr.T.Jacob John has to say : “The strains reintroduced were of the vaccine virus which is less virulent (compared to the wild virus). Its mutation would have required multiple exposures,” “The risk is low, but it should have remained zero.”
In reality If the virus does turn virulent, the risk would be greater for kids who have received only the oral vaccines from which the type-2 strain was removed in 2016.Children who have received three doses of trivalent oral vaccination (given before April 2016) are protected. After 2016, children who received IPV are protected.

So who are at risk ?

The risk will be for kids who had only bivalent oral vaccination (given after April 2016) or no polio vaccine at all, as there is no herd immunity (the resistance of an entire population to a disease) to protect them anymore, because IPV protects only individuals).So this applies to children of parents who vehemently take part in the antivaccination campaigns and who simply neglect their kids health needs .IPV often happens to be in short supply in India leaving many children in the country unvaccinated and putting them at risk of contracting vaccine-derived polio as happened since mid-2016. IPV penetration being lower among marginalised communities,children in slums, conflict areas, orphan children, and children of migrant workers are more at risk.