Impact of Malnutrition on Rotavirus Vaccine Immunogenicity in Under-Five Children in Zamfara State

Rotavirus vaccine immunogenicity is consistently lower in children in low-income African settings than in high-income countries, and emerging evidence suggests malnutrition may be a key modifier of vaccine-induced immune responses. Zamfara State, North West Nigeria, has among the highest rates of childhood stunting and wasting in the country, making it an important context for studying nutrition-vaccine interactions. This study evaluates the impact of malnutrition on rotavirus vaccine immunogenicity among infants receiving the Rotarix vaccine at two and three months through routine EPI services in Zamfara State. A prospective cohort design will recruit 250 infants at 6 weeks of age from immunisation clinics in Gusau, Tsafe, and Maru local government areas. Anthropometric assessments (weight-for-age, weight-for-height, MUAC) will classify nutritional status. Blood samples collected at 4 weeks post-second vaccine dose will be analysed for anti-rotavirus IgA titres by ELISA as the primary immunogenicity endpoint. Faecal samples will be collected to assess intestinal rotavirus IgA secretion. Multivariate regression will model the relationship between nutritional status parameters and IgA seroconversion rates. Published studies from East Africa demonstrate 30 to 50 percent lower seroconversion rates in stunted versus non-stunted infants. Findings will provide North West Nigeria-specific evidence on nutrition-immunogenicity interactions, informing advocacy for integrated nutrition-immunisation programmes. Keywords: rotavirus vaccine, immunogenicity, malnutrition, under-five children, Zamfara State