Resurgent rotavirus diarrhoea outbreak five years after introduction of rotavirus vaccine in Botswana, 2018

INTRODUCTION

Botswana had a resurgent diarrhea outbreak in 2018, mainly affecting children under five years old. Botswana introduced rotavirus vaccine (RotarixTM) into the national immunization programme in July 2012. Official rotavirus vaccine coverage estimates averaged 77.2% over the five years following introduction.

MATERIALS AND METHODS

The outbreak was investigated using multiple data sources, including stool laboratory testing, immunization data review, water assessment, and vaccine storage assessment. We reviewed official reports of the routine immunization data from 2013 to 2017 and compared district-level rotavirus vaccine coverage with district-level attack rates during the outbreak.

RESULTS

During the outbreak, a total of 228 stool samples were tested at the national health laboratory and 152 (67%) of the specimens were positive for rotavirus. A portion of adequate samples (80) were selected for referral to the Regional Reference Lab. The laboratory testing of 80 samples at the Regional Reference Laboratory in South Africa showed that 91% of the stool samples were positive for rotavirus, and the dominant strain 47/80 (58.7%) was G3P[8]. The immunization data showed that rotavirus vaccine coverage varied widely among districts, and there was no correlation between districts with high attack rates and those with low immunization coverage. Water assessment showed that some water sources were contaminated with E Coli. There was no problem with vaccine storage.

CONCLUSION

The outbreak was caused by rotavirus G3P[8], a strain that was not common in the country prior to the outbreak. Despite the significant pressure and anxiety that outbreaks cause, the number of diarrhea cases and deaths were less compared to pre-vaccine era due to the impact of vaccination. This highlights the need for continuous implementation of high impact child survival interventions.