Exploring the path to polio eradication: insights from consecutive seroprevalence surveys among Pakistani children

• Published in: Frontiers in public health Vol. 12; p. 1384410
• Main Authors: Hussain, Imtiaz, Umer, Muhammad, Khan, Ahmad, Sajid, Muhammad, Ahmed, Imran, Begum, Kehkashan, Iqbal, Junaid, Alam, Muhammad M, Safdar, Rana M, Baig, Shahzad, Voorman, Arie, Partridge, Jeffrey, Soofi, Sajid
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 27.03.2024
• Subjects: Child; Cross-Sectional Studies; eradication; Humans; Pakistan; Pakistan - epidemiology; Poliomyelitis - epidemiology; Poliomyelitis - prevention & control; Poliovirus; Poliovirus Vaccine, Inactivated; Poliovirus Vaccine, Oral; Public Health; Seroepidemiologic Studies; seroprevalence; type 2 immunity; Pakistan; seroprevalence; Pakistan; type 2 immunity; eradication; poliovirus
• ISSN: 2296-2565; 2296-2565
• DOI: 10.3389/fpubh.2024.1384410

After trivalent oral poliovirus vaccine (tOPV) cessation, Pakistan has maintained immunity to type 2 poliovirus by administering inactivated polio vaccine (IPV) in routine immunization, alongside monovalent OPV type 2 (mOPV2) and IPV in supplementary immunization activities (SIAs). This study assesses the change in poliovirus type 2 immunity after tOPV withdrawal and due to SIAs with mOPV2 and IPV among children aged 6-11 months. Three cross-sectional sequential serological surveys were conducted in 12 polio high-risk areas of Pakistan. 25 clusters from each geographical stratum were selected utilizing probability proportional to size. Seroprevalence of type 2 poliovirus was 49%, with significant variation observed among surveyed areas; <30% in Pishin, >80% in Killa Abdullah, Mardan & Swabi, and Rawalpindi. SIAs with IPV improved immunity from 38 to 57% in Karachi and 60 to 88% in Khyber. SIAs with IPV following mOPV2 improved immunity from 62 to 65% in Killa Abdullah, and combined mOPV2 and IPV SIAs in Pishin improved immunity from 28 to 89%. Results also reflected that immunity rates for serotypes 1 and 3 were consistently above 90% during all three phases and across all geographical areas. The study findings highlight the importance of implementing effective vaccination strategies to prevent the re-emergence of poliovirus. Moreover, the results provide crucial information for policymakers working toward achieving global polio eradication.