New Delhi: Central Drugs Standard Control Organization (CDSCO) on Saturday constituted a three-member team to investigate a recent case of tainted polio vaccine.

Traces of polio type-2 virus, a strain that was known to have been eradicated from India, were found in some batches of oral polio vaccine (OPV) manufactured by Ghaziabad-based Bio-Med Pvt. Ltd, posing a serious threat of polio resurfacing in India.

“The three-member team will start its investigation on Wednesday to identify the possible cause of contamination," said a senior health ministry official, requesting anonymity.

The company on its website positions its polio vaccine as one of its ‘power brands’ and claims to practise rigorous “pharmacovigilance activities", which are related to the detection, assessment, understanding and prevention of adverse events or any other vaccine-related problems to ensure safety.

Officials, however, said that the company’s conduct raises suspicion. “Bio-Med is the major contributor of polio vaccine. They may want to keep it alive. India eliminated the type 2 strain in 2016. Hence, type-2 containing poliovirus vaccine (ToPV) was phased out in April 2016. The company was supposed to have destroyed the batches of trivalent ToPV vaccine, which may not have been done in the present case. There are a lot of reasons that could have led to the contamination and it needs a thorough investigation. Three members will investigate and find out the root cause of contamination," said the official.

The company was supplying polio vaccines only for the government-run immunization programme and about 50,000 vials (one vial has 20 doses) of contaminated vaccine may have possibly been used in Uttar Pradesh, Maharashtra and Telangana, another official said. Directions have been given for the withdrawal of the vaccine manufactured by Bio-Med and recalled batches have been sent for testing to the Central Drug Laboratory (CDL), Kasauli. “The unused vials have been stocked in the warehouses and 13 batches of samples have so far been tested at CDL," said the second official.

The ministry has approached other companies such as Bharat Biotech and Panacea Biotec to ensure that there is no shortage of vaccine.

India achieved a major success in its battle against polio after years of effort and was finally declared polio free in 2014. The last case was reported on 13 January 2011, when Rukhsar from Howrah was infected with type-1 polio virus. However, the possibility of the polio virus resurfacing always loomed over the country. “The present case cannot be taken lightly and holds the possibility of this threat re-entering India. What needs to be probed is the health ministry’s own system of checks and balances. All samples are sent for testing to the government laboratory in Kasauli. Why was the strain not detected in testing?" asked a public health expert, requesting anonymity.

The contamination came to light about 15 days when the World Health Organization found signs of the virus in stool samples from surveillance reports from Uttar Pradesh. The samples were sent for further testing and confirmed contamination with type-2 virus.

As part of intensive surveillance, sewage samples are collected from 45 sites across eight states and tested for poliovirus in five accredited polio laboratories in the country. This is in addition to stool samples collected from individuals reporting sudden onset of paralysis or other polio like symptoms. Every year nearly 75,000 stool samples are collected and tested in polio laboratories in India.

“This is when the WHO found type-2 polio vaccine virus in some sewage and stool samples during their routine surveillance," the WHO official said.

“This detection indicates the use of a type-2 poliovirus containing vaccine, despite the fact that type-2 containing poliovirus vaccine (trivalent oral polio vaccine) has been phased out globally, and in India, in April 2016, as a part of the polio End Game strategy. As elsewhere, bivalent oral polio vaccine (bOPV) has replaced the trivalent OPV (tOPV) in all polio campaigns and routine immunization in India," said a WHO official.

The managing director of Bio-Med was arrested on Friday after the central drug regulator filed a FIR in the case. “The other directors, who are family members of the managing director, are absconding ever since," said the second ministry official mentioned above.

Calls to Bio-Med’s landline phone outside office hours were not answered.

The decision to switch to bOPV from tOPV was taken following certification of global eradication of type-2 wild poliovirus. Removing type-2 component from polio vaccine was done with the aim of minimizing the risk of vaccine derived poliovirus type-2.

“India continues to conduct mass vaccination campaigns against polio, using bOPV, as advised by the India Expert Advisory Group, to maintain high immunity against polio," said the WHO official.

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