Effectiveness of Monovalent Rotavirus Vaccine After Programmatic Implementation in Botswana: A Multisite Prospective Case-Control Study

Abstract

Background: Botswana introduced monovalent G1P rotavirus vaccine (RV1) in July 2012, providing one of the first opportunities to assess the effectiveness of routine RV1 vaccination in a high-burden setting in Africa. We sought to determine the effectiveness of RV1 against rotavirus diarrhea hospitalization using a case-control evaluation.

Methods: Vaccine age-eligible children <5 years of age admitted with diarrhea at 4 hospitals in Botswana were enrolled from June 2013 to April 2015. Card-confirmed vaccine history was compared between case patients (children with laboratory-confirmed rotavirus diarrhea) and nonrotavirus "test-negative" diarrhea controls. Vaccine effectiveness (VE) was computed using unconditional logistic regression models adjusting for age, birth month/year, and hospital. Sequence-based genotyping was performed on antigen-positive samples.

Results: Among 242 case patients and 368 controls, 82% (199/242) and 92% (339/368), respectively, had received ≥1 doses of RV1. Effectiveness of a full series (2 doses) of RV1 against rotavirus diarrhea requiring hospitalization was 54% (95% confidence interval [CI], 23%-73%); 1 dose of RV1 was 48% (95% CI, 1%-72%) effective. Effectiveness was 59% (95% CI, 4%-83%) against rotavirus caused by G2P, the most common (37%) circulating genotype. However, the effectiveness of 2 RV1 doses was significantly higher in children with no undernutrition (VE, 75% [95% CI, 41%-89%]), compared to those with moderate or severe undernutrition (VE, -28% [95% CI, -309% to 60%]) (P= .02).

Conclusions: Routine RV1 vaccination in Botswana showed effectiveness similar to that in clinical trials in Africa, including against a serotype fully heterotypic to the vaccine. Undernutrition may in part explain the lower rotavirus VE in low-income settings.

Keywords: Africa; diarrhea; rotavirus; rotavirus vaccine; vaccine effectiveness.