PESHAWAR: Khyber Pakhtunkhwa has recorded six vaccine derived poliovirus type 2 (VDPV2) cases, prompting the authorities to carry out a risk assessment and get stock of vaccine from the World Health Organisation to scale up immunity of children.

The virus, thought to have been eradicated in 1999 from the world, re-emerged in Pakistan owing to poor routine immunisation, malnourishment and unhygienic environment. Therefore, the World Health Organisation withdrew the vaccine in 2016 from polio eradication programme.

The VDPV2 cases reached to 18 as 12 cases were reported in October. These include 12 from Khyber Pakhtunkhwa, which is grappling with the outbreak of P1 virus that has so far infected 91 children in the province.

“Risk assessment is underway based on which the response proposal will be taken up with Global Advisory Group for release of vaccine from WHO stockpiles,” Dr Rana Safdar, coordinator of National Emergency Operations Centre, told Dawn.

He said that all the cases were counted in 2019. He added that the children having the vaccine derived VDPV2 virus last year belonged to the areas with weak routine immunisation coverage.

Re-emergence of virus attributed to poor immunisation, malnourishment and unhygienic conditions

“All previous cases have been responded. As per guidelines, first response is conducted in two weeks followed by two follow up rounds,” said Dr Rana.

The newly-infected children belong to Khyber, Peshawar, Lakki Marwat, Bajaur, Torghar and Mohmand districts. In October, polio cases were reported from Kohistan, Torghar, Charsadda and Islamabad. Only two of the confirmed cases have one dose of IPV from routine immunisation programme.

Meanwhile, the virus has been found in the sewerage water samples collected from Peshawar, Kohat, Gujranwala, Dera Ismail Khan and Islamabad.

“To mitigate the associated risks after the cases in October, we have undertaken extensive investigations to understand the characteristics of the virus. We have taken steps to protect children in areas where it has been detected,” a senior official told this scribe.

The polio cases, derived from vaccines, generally emerge after circulating in under-immunised communities for at least 12 months, according to WHO. But the type 2 virus was removed from oral vaccines in 2016, so it is not clear how the new vaccine derived cases occurred.

Khyber Pakhtunkhwa, which is in the limelight due to highest P1 cases in the world, is looking towards the federal government and world health agency prior to initiating preventive measures.

“Not only P2 but Pakistan is also affected by wild poliovirus type 1 (WPV1), which is comparatively more virulent strain and is more geographically widespread and therefore represents the greatest risk to the children of Pakistan,” a WHO official said.

Therefore, priority was to continue intensifying efforts to eradicate wild poliovirus type 1 as urgently as possible, while also protecting children against other poliovirus strains, he said.

“Pakistan has struggled to contain polio this year, recording 135 cases of polio type 1 in 2019. The continuous and violent outbreak highlights the importance of strong surveillance systems and need to reach children everywhere with polio vaccines,” he said.

Khyber Pakhtunkhwa is planning to conduct P2 vaccination campaign in 14 districts within a month because there has been mounting concern that number of both P1 and 2 viruses has been spreading to other districts.

The new P2 cases are seen as fresh blow to polio eradication efforts amid the faltering immunisation programme. Pakistan’s polio cases have increased 11-time in 2019 compared to 2018.

Published in Dawn, January 15th, 2020