Modelling the spread of serotype-2 vaccine derived-poliovirus outbreak in Pakistan and Afghanistan to inform outbreak control strategies in the context of the COVID-19 pandemic.

Background: Since July 2019, Pakistan and Afghanistan have been facing an outbreak of serotype-2 circulating vaccine derived poliovirus (cVDPV2) in addition to continued transmission of serotype-1 wild poliovirus (WPV1) and SARS-CoV-2 in 2020. Understanding the risks of cVDPV2 transmission due to pause of global vaccination efforts and the impact of potential vaccination response strategies in the current context of COVID-19 mitigation measures is critical.

Methods: We developed a stochastic, geographically structured mathematical model of cVDPV2 transmission which captures both mucosal and humoral immunity separately and allows for reversion of serotype-2 oral polio vaccine (OPV2) virus to cVDPV2 following vaccine administration.

Detection of SARs-CoV-2 in wastewater using the existing environmental surveillance network: A potential supplementary system for monitoring COVID-19 transmission.

The ongoing COVID-19 pandemic is caused by SARs-CoV-2. The virus is transmitted from person to person through droplet infections i.e.

Quantifying movement patterns and vaccination status of high risk mobile populations in Pakistan and Afghanistan to inform poliovirus risk and vaccination strategy.

Background: Stopping serotype 1 wild poliovirus transmission in Pakistan and Afghanistan requires ensuring all children <5 years of age are repeatedly vaccinated, including the large proportion living in mobile groups. Vaccinating children living in high-risk mobile populations (HRMPs) remains a priority for the polio programme.

Methods: In 2017-2018, group-level censuses were conducted in 43 districts of Pakistan, gathering information for all HRMP children <5 years of age residing in settlements.

Needle-free injectors for mass administration of fractional dose inactivated poliovirus vaccine in Karachi, Pakistan: A survey of caregiver and vaccinator acceptability.

The first large-scale vaccination campaign using needle-free jet injectors to administer fractional doses of inactivated poliovirus vaccine (fIPV) was conducted in Karachi, Pakistan, in February 2019. Data on acceptability of jet injectors were collected from 610 vaccinators and 4898 caregivers during the first four days of the campaign. Of those with prior needle and syringe experience, both vaccinators and caregivers expressed a strong preference for jet injectors (578/592 [97.

Assessing the sensitivity of the polio environmental surveillance system.

Background: The polio environmental surveillance (ES) system has been an incredible tool for advancing polio eradication efforts because of its ability to highlight the spatial and temporal extent of poliovirus circulation. While ES often outperforms, or is more sensitive than AFP surveillance, the sensitivity of the ES system has not been well characterized. Fundamental uncertainty of ES site sensitivity makes it difficult to interpret results from ES, particularly negative results.

Spatial model for risk prediction and sub-national prioritization to aid poliovirus eradication in Pakistan.

Background: Pakistan is one of only three countries where poliovirus circulation remains endemic. For the Pakistan Polio Eradication Program, identifying high risk districts is essential to target interventions and allocate limited resources.

Methods: Using a hierarchical Bayesian framework we developed a spatial Poisson hurdle model to jointly model the probability of one or more paralytic polio cases, and the number of cases that would be detected in the event of an outbreak.