Prevalence of Group a Rotavirus before and after Vaccine Introduction in Mukuru Informal Settlement in Kenya

Abstract

Background: Rotavirus vaccines have been shown to be a lifesaving and cost-effective public health intervention in Africa and have resulted in reduced rotavirus mortality. In Kenya, rotavirus diarrhea causes 19% of hospitalizations and 16% of clinic visits among children <5 years of age and causes 4471 deaths and 8,781 hospitalizations per year. Nationally, rotavirus disease costs the health care system $10.8 million annually. It is estimated that routine vaccination with a 2-dose rotavirus vaccination series would avert approximately 2,467 deaths (55%), 5,724 hospitalizations (65%), 852, 589 clinic visits (59%) and would save 58 disability-adjusted life-years (DALYs) per 1000 children annually. In July 2014, Kenya introduced rotavirus vaccine into its routine expanded programme  immunisation, with two doses given at 6 and 10ths week of age.WHO recommend having  surveillance studies before and after vaccine as baseline data and monitoring the possible effect after vaccine introductions. The aim of this study was to determine the prevalence of rotavirus in pre- and post-vaccine stool samples collected from children under five years, attending two selected clinics in Mukuru informal settlement in Nairobi, Kenya.

Methods: Archived samples collected during a Salmonella surveillance study (SSC No. 2074) conducted between July 2013 and July 2015 were used for this study. A total of 270 samples (150 pre-vaccine and 120 post-vaccine) were tested for rotavirus using ELISA Prospect kit (Oxoid Ltd UK) and data analyzed using SPSS version 20.

Results: Rotavirus prevalence was 10% (15/150) and 5% (6/120) in pre-vaccine and post-vaccine samples respectively. There was significant difference in prevalence pre and post vaccine samples for children less than 12 months (P=0.014), 13-24 months (P=0.002) and over 49 months (P=0.01). However, there was no difference in prevalence for age categories 25-36 and 37- 48 months.

Conclusion: This study showed a reduction in prevalence of Group A rotavirus in Mukuru selected clinics one year after vaccine introduction into National immunization program in Kenya. Rotavirus prevalence differed significantly for cases less than 12 months, 13-24 months and over 49 months pre and post vaccine introduction. However, there was no difference in prevalence for age category 25-36 and 37- 48 months thus the vaccine proved to have a significant protection in the most vulnerable group of children.

Keywords: Rotavirus, Kenya, vaccine, pre-vaccine, post-vaccine, prevalence, Kenya.