Modeling Poliovirus Transmission in Pakistan and Afghanistan to Inform Vaccination Strategies in Undervaccinated Subpopulations.

Due to security, access, and programmatic challenges in areas of Pakistan and Afghanistan, both countries continue to sustain indigenous wild poliovirus (WPV) transmission and threaten the success of global polio eradication and oral poliovirus vaccine (OPV) cessation. We fitted an existing differential-equation-based poliovirus transmission and OPV evolution model to Pakistan and Afghanistan using four subpopulations to characterize the well-vaccinated and undervaccinated subpopulations in each country. We explored retrospective and prospective scenarios for using inactivated poliovirus vaccine (IPV) in routine immunization or supplemental immunization activities (SIAs). The undervaccinated subpopulations sustain the circulation of serotype 1 WPV and serotype 2 circulating vaccine-derived poliovirus. We find a moderate impact of past IPV use on polio incidence and population immunity to transmission mainly due to (1) the boosting effect of IPV for individuals with preexisting immunity from a live poliovirus infection and (2) the effect of IPV-only on oropharyngeal transmission for individuals without preexisting immunity from a live poliovirus infection. Future IPV use may similarly yield moderate benefits, particularly if access to undervaccinated subpopulations dramatically improves. However, OPV provides a much greater impact on transmission and the incremental benefit of IPV in addition to OPV remains limited. This study suggests that despite the moderate effect of using IPV in SIAs, using OPV in SIAs remains the most effective means to stop transmission, while limited IPV resources should prioritize IPV use in routine immunization.

Using Nonpolio Enterovirus Detection to Assess the Integrity of Stool Specimens Collected From Acute Flaccid Paralysis Cases in Somalia During 2014-2017.

BACKGROUND: Despite insecurity challenges in Somalia, key indicators for acute flaccid paralysis (AFP) surveillance have met recommended targets. However, recent outbreaks of vaccine-derived polioviruses have raised concerns about possible gaps. We analyzed nonpolio enterovirus (NPEV) and Sabin poliovirus isolation rates to investigate whether comparing these rates can inform about the integrity of stool specimens from inaccessible areas and the likelihood of detecting circulating polioviruses. METHODS: Using logistic regression, we analyzed case-based AFP surveillance data for 1348 cases with onset during 2014-2017. We assessed the adjusted impacts of variables including age, accessibility, and Sabin-like virus isolation on NPEV detection. RESULTS: NPEVs were more likely to be isolated from AFP case patients reported from inaccessible areas than accessible areas (23% vs 15%; P = .01). In a multivariable model, inaccessibility and detection of Sabin-like virus were positively associated with NPEV detection (adjusted odds ratio [AOR], 1.75; 95% confidence interval [CI], 1.14-2.65; and AOR, 1.79; 95% CI, 1.07-2.90; respectively), while being aged ≥5 years was negatively associated (AOR, 0.42; 95% CI, 0.20-0.85). CONCLUSIONS: Rates of NPEV and Sabin poliovirus detection in inaccessible areas suggest that the integrity of fecal specimens tested for AFP surveillance in Somalia can generate useful AFP data, but uncertainties remain about surveillance system quality.

Using Predictive Evaluation to Design, Evaluate, and Improve Training for Polio Volunteers.

BACKGROUND: Predictive Evaluation (PE) uses a four-step process to predict results then designs and evaluates a training intervention accordingly. In 2012, the Sustainable Management Development Program (SMDP) at the Centers for Disease Control and Prevention used PE to train Stop Transmission of Polio (STOP) program volunteers. METHODS: Stakeholders defined specific beliefs and practices that volunteers should demonstrate. These predictions and adult learning practices were used to design a curriculum to train four cohorts. At the end of each workshop, volunteers completed a beliefs survey and wrote goals for intended actions. The goals were analyzed for acceptability based on four PE criteria. The percentage of acceptable goals and the beliefs survey results were used to define the quality of the workshop. A postassignment adoption evaluation was conducted for two cohorts, using an online survey and telephone or in-person structured interviews. The results were compared with the end of workshop findings. RESULTS: The percentage of acceptable goals across the four cohorts ranged from 49% to 85%. In the adoption evaluation of two cohorts, 88% and 94% of respondents reported achieving or making significant progress toward their goal. A comparison of beliefs survey responses across the four cohorts indicated consistencies in beliefs that aligned with stakeholders' predictions. CONCLUSIONS: Goal statements that participants write at the end of a workshop provide data to evaluate training quality. Beliefs surveys surface attitudes that could help or hinder workplace performance. The PE approach provides an innovative framework for health worker training and evaluation that emphasizes performance.