Protocol for a systematic review and meta-analysis of fractional dose compared with standard dose inactivated polio vaccination in children

INTRODUCTION: WHO recommends the introduction of at least one single dose of inactivated polio vaccine (IPV) in routine immunisation schedules. Thus, there has been an increased demand and concurrent supply shortages of IPV worldwide. One of the strategies to improve access is the use of fractional instead of full doses of IPV. We aim to compare the effects of fractional with standard doses of IPV. METHODS AND ANALYSIS: We will include randomised trials, non-randomised trials, case-control studies and cohort studies that compared fractional with full doses of IPV among children aged 5 years or younger. We will search for eligible studies among published and grey literature. Two authors will independently screen the results of the search, select studies, extract data and assess risk of bias. We will stratify analyses by study design, type of poliovirus, type of outcome measure and number of IPV doses given. For each type of poliovirus, we will pool the outcome data from studies using random-effects meta-analyses. Statistical heterogeneity will be assessed using the χ(2) test of homogeneity and quantified using the I(2) statistic. To investigate statistical heterogeneity, subgroup analyses will be performed based on the timing of the first fractional dose, age of administration, immunisation schedules and country income status. Sensitivity analyses will be used to assess if the effect of IPV fractional dosing is affected by study design, risk of bias and methods of meta-analysis. ETHICS AND DISSEMINATION: We obtained approval from the University of Cape Town Human Research Ethics Committee (HREC REF: 412/2018). The findings of this review will provide evidence for decision-making with regards to IPV dosage, eventually improving access to the vaccine by stretching vaccine supplies. The results will be published in the University of Cape Town online library and in a peer reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42018092647.