Factors associated with the circulation of vaccine-derived polioviruses in children under five in Kilwa, Haut-Katanga province, Democratic Republic of Congo, 2022-2023.

INTRODUCTION

Since the World Health Organization declared the African region free of wild poliovirus in August 2020, vaccine-derived polioviruses (VDPV) have remained the only form of poliovirus still circulating on the continent, including in the Democratic Republic of the Congo (DRC). This study aimed to identify factors associated with VDPV infection among children under five in Haut-Katanga Province, specifically in the Kilwa health zone.

METHODS

We conducted a case-control study based on secondary analysis of data from the National Institute of Biomedical Research and the Expanded Programme on Immunization. The dependent variable was infection with a vaccine-derived poliovirus. Independent variables included participants' vaccination and epidemiological status, as well as selected environmental factors. Associations were assessed using univariate logistic regression, with a significance threshold set at 5%.

RESULTS

No association was found between VDPV infection and the following variables in children under five: number of oral poliovirus vaccine doses received, number of inactivated poliovirus vaccine doses received, recent diarrhoeal episode, contact with a positive case, source of drinking water, open defecation, dwelling cleanliness, or wealth index. However, a significant association was observed with malnutrition: malnourished children were at increased risk of VDPV infection (OR = 2.33, 95% CI: 1.12-4.81).

CONCLUSION

Malnutrition appears to be a risk factor for infection with vaccine-derived poliovirus. These findings highlight the need to strengthen nutritional interventions in high-risk areas to support polio control efforts.