Polio Eradication in Pakistan, January 2017–September 2018

This page summarizes a report in CDC's MMWR by CDC, the World Health Organization (WHO), UNICEF and Pakistani health authorities, covering January 2017 to September 2018.

Of the three wild poliovirus (WPV) types, only type 1 (WPV1) has turned up in polio cases or environmental samples anywhere in the world since 2012. Pakistan was one of just three countries, with Afghanistan and Nigeria, where WPV1 transmission had never been interrupted.

Cases were falling

The 12 children with WPV1 from January 2017 to September 2018 were aged 4 to 38 months. By parental recall, none of the 2018 cases were "zero-dose" children: all had received oral poliovirus vaccine (OPV) in campaigns, from 3 to more than 7 doses, and one had also had three OPV doses and one inactivated poliovirus vaccine (IPV) dose through routine services.

But the virus was still circulating

Sewage sampling at 59 sites backs up surveillance of acute flaccid paralysis (AFP). At the 39 sites sampled monthly through 2016–2018, the share of samples positive for WPV1 did not substantially change even as cases fell:

Most came from the core reservoirs: Karachi, the Quetta block (Pishin, Killa Abdullah and Quetta districts) and Peshawar. That points to children missed by vaccination and to weak program performance.

AFP surveillance itself was strong. In 2017 every province beat the targets of two nonpolio AFP cases per 100,000 children under 15 and 80% of cases with adequate specimens. For January 2017–September 2018, the national nonpolio AFP rate was 12.9 (11.5–24.1 across provinces), and 89% of cases had adequate stool specimens.

Vaccination

Routine coverage. WHO and UNICEF estimated that 75% of infants received three OPV doses (OPV3) by age 1 in 2017, the same as in 2016. Provinces varied widely: administrative OPV3 coverage was highest in Azad Jammu and Kashmir (95%) and Islamabad (91%), and lowest in Balochistan (35%) and the Khyber Pakhtunkhwa Tribal Districts (50%).

Campaigns. From January 2017 to September 2018 Pakistan ran nine nationwide and eight subnational campaigns with bivalent OPV (types 1 and 3), plus 35 small campaigns in response to WPV1 findings. Two rounds combining IPV with bivalent OPV targeted 3,081,900 children in 2017 and 1,287,835 in 2018 in Balochistan, the Khyber Pakhtunkhwa Tribal Districts and Karachi. Monitoring surveys showed high overall quality, but some Union Councils (subdistricts) repeatedly underperformed.

Community health workers. By August 2018, 18,153 locally recruited community health workers were vaccinating children in their own communities in 16 districts of the Khyber Pakhtunkhwa Tribal Districts, Balochistan and Sindh. Of them, 85% were women, who can enter homes in these culturally and religiously conservative areas more easily than men.

Transit points. 1,106 permanent transit points along major migration routes, at transport hubs in every province and at official border crossings with Afghanistan vaccinate children on the move.

Obstacles

• Refusals. Parents' refusals of OPV had grown, driven by fast-spreading misconceptions about vaccine safety and effectiveness, and by marginalized urban communities demanding other basic services, such as clean water and maternal and adult health care. The program answered with a strong communication campaign through traditional and social media, work with community opinion leaders, and better messages for frontline vaccinators; eradication partners were working with development agencies on basic services.
• Movement across the border. Afghanistan had reported 13 WPV1 cases in 2018 as of September 18, in two cross-border corridors: a Northern Corridor that includes the Khyber Pakhtunkhwa Tribal Districts and a Southern Corridor that includes Balochistan. Genetic sequencing linked viruses on both sides. The two countries had synchronized campaigns and held regular meetings through their Emergency Operation Centers for several years, but coordination on vaccinating migrants needed further work. Some transit teams also failed to cover travel in every direction.

What it will take

Frequent, high-quality campaigns have been linked to the fall in cases. Ending WPV1 transmission will require keeping them up, improving routine immunization, and fixing vaccination in the underperforming Union Councils of each reservoir.

Sources

• Hsu C, Mahamud A, Safdar M, et al. "Progress Toward Poliomyelitis Eradication — Pakistan, January 2017–September 2018." MMWR 67(44). https://www.cdc.gov/mmwr/volumes/67/wr/mm6744a5.htm
• The report's figures are not reproduced, because the report was prepared jointly with WHO, UNICEF and Pakistani institutions.