Poliovirus excretion among children with primary immune deficiency in Pakistan: a pilot surveillance study protocol

Children with primary immunodeficiency disorders (PID) are more susceptible to developing viral infections and are at a substantially increased risk of developing paralytic poliomyelitis. Such children, if given oral polio vaccines tend to excrete poliovirus chronically that may lead to the propagation of highly divergent vaccine-derived poliovirus (VDPV). Consequently, they may act as a reservoir for the community by introducing an altered virus potentially imposing a risk to global polio eradication. However, the risks of chronic and prolonged excretion are not well characterised in the study context. This study seeks to establish a pilot surveillance system for successful identification and monitoring of VDPV excretion among children with PID. It will assess whether the Jeffrey Modell warning signs of PID can be used as an appropriate screening tool for PID in Pakistan.

In this pilot surveillance, recruitment of PID cases is currently done at participating hospitals in Pakistan. Potential children are screened and tested against the Jeffrey Modell Foundation (JMF) warning signs for immunodeficiency and their stool is collected to test for poliovirus excretion. Cases excreting poliovirus are followed until the two consecutive negative stool samples are obtained over a period of 6 months. The data will be analysed to calculate hospital-based proportions of total Immunodeficiency-related vaccine-derived poliovirus (iVDPV) cases over a 2-year period and to determine the sensitivity and specificity of the JMF signs.

This protocol was reviewed and approved by the WHO (WHO Reference-2018/811124-0), Aga Khan University (AKU ERC-2018-0380-1029) and National Bioethics Committee (Ref No. 4-87 NBC-308-Y2). The results will be published in an open access peer-reviewed scientific journal and presented to the iVDPV Working Group members, policy-makers, paediatric consultants and fellow researchers with the same domain interest. It may be presented in scientific conferences and seminars in the form of oral or poster presentations.