The vaccination drive was set to commence on December 18 (Monday). It was also postponed in November last month.

At least six polio cases, including four in KP and two in Punjab, have so far been reported this year, according to the Pakistan Polio Eradication Programme.

The development comes after recent terrorist attacks in the two districts. Three policemen were killed when a group of terrorists attacked a building in the Police Lines area in Tank on Friday.

According to the Inter-Services Public Relations, all five terrorists were killed during the operation to clear the area.

The area is two kilometers away from Dera Ismail Khan where at least 25 army soldiers were martyred in separate incidents earlier this week.

Experts have often described police as a “soft target” for terrorists, saying that such attacks affect the first line of defence in the country.

Poliovirus was found in six environmental samples collected from five districts of the country earlier this month.

The virus was isolated from two sewage samples from Quetta and one each from Karachi Malir, Peshawar, Hub and Tank districts, collected between November 13 and 20.

“In 84 out of the 90 positive sewage samples this year, we have detected the imported cluster, which highlights the constant risk of poliovirus spread through cross-border transmission,” said Federal Minister for Health Dr Nadeem Jan on December 11. “As long as the virus remains in circulation, no child anywhere is safe from it.”