Widespread paralytic poliomyelitis in Pakistan: A case-control study to determine risk factors and implications for poliomyelitis eradication

Despite substantial efforts to eradicate poliomyelitis by administering ora l poliovirus vaccine through routine immunization and annual national immun ization days (NIDs), Pakistan reported 22% (1147) of the worldwide cases in 1997, Reasons for continued high poliomyelitis incidence include failure t o vaccinate, vaccine failure, or inadequate immunization strategies, A case -control study was conducted to measure vaccination status and reasons for undervaccination among 66 poliomyelitis cases and 130 age- and neighborhood -matched controls. Cases were undervaccinated through routine immunization (matched odds ratio [MOR], 0.3; 95% confidence interval [CI], 0.1-0.5); how ever, NID immunization was similar for cases and controls (MOR, 0.6; 95% CI , 0.3-1.2), Reasons for undervaccination included not being informed, consi dering vaccination unimportant, and long distances to vaccination sites. Fa ilure to vaccinate through routine immunization was a major risk factor for poliomyelitis in Pakistan, Successful NIDs alone will not interrupt poliov irus circulation in Pakistan, and children remain at risk unless routine im munization is strengthened or additional supplementary immunization is prov ided.