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Published on: January 28, 2019
Post-vaccine rotavirus genotype distribution in Nairobi County, Kenya
Joshua Ndung'u Gikonyo1, Betty Mbatia2, Patrick W Okanya1
1Department of Biochemistry and Biotechnology, The Technical University of Kenya (TU-K), PO Box 52428-00200, Nairobi, Kenya.
Insights
The G1P[8] rotavirus strain dominance decreased in Nairobi children after vaccine introduction. An increase in G2 genotypes, including G2P[4] and G2P[6], was observed, indicating a shift in circulating rotavirus strains.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Rotaviruses are a leading cause of severe gastroenteritis in young children globally.
- Kenya introduced the G1P8 monovalent rotavirus vaccine (Rotarix) in 2014.
- Post-vaccine rotavirus genotype surveillance in Nairobi County was previously unstudied.
Purpose of the Study:
- To determine the prevalence of rotavirus genotypes in children under five in Nairobi County, Kenya, after the introduction of the rotavirus vaccine.
- To understand the impact of the G1P8 vaccine on circulating rotavirus strains.
Main Methods:
- Stool samples were collected from children under five with confirmed diarrhea and vaccination status.
- Rotavirus antigen detection was performed using enzyme immunoassay (EIA).
- Genotyping was conducted using polyacrylamide gel electrophoresis (PAGE), RT-PCR, and nested PCR.
Main Results:
- The most prevalent rotavirus genotypes identified were G1P[8] (38.8%), G9P[8] (20.4%), and G2P[4] (12.2%).
- A decrease in the dominance of the G1P[8] strain was observed post-vaccination.
- There was a notable increase in the prevalence of G2 genotypes (G2P[4], G2P[6]) and G9P[8].
- Mixed genotypes, such as G3P[4][8], were also detected.
Conclusions:
- The study highlights a significant shift in rotavirus genotype distribution following vaccine introduction in Nairobi.
- Findings underscore the necessity for ongoing surveillance to monitor rotavirus strain ecology and vaccine effectiveness.
- Longitudinal epidemiological studies are crucial for assessing the long-term impact of rotavirus vaccination programs.
Background:
Rotaviruses are primary etiological agents of gastroenteritis in young children. In Kenya, G1P8 monovalent vaccine (Rotarix) was introduced in July 2014 for mandatory vaccination of all newborns at 6 and 10 weeks of age. Since then, no studies have been done to identify the rotavirus genotypes circulating in Nairobi County, Kenya, following the vaccine introduction, hence the post-vaccine genotype distribution is not known.
Objectives:
The aim of this study was to determine the post-vaccine occurrence of rotavirus genotypes in children <5 years of age in Nairobi County, Kenya.
Methods:
Stool samples were collected from children presenting with diarrhea for whom the vaccination status was card-confirmed. Fecal samples were analyzed for rotavirus antigen using a commercial enzyme immunoassay (EIA) kit, followed by characterization by polyacrylamide gel electrophoresis, RT-PCR, and nested PCR genotyping, targeting the most medically important genotypes.
Results:
The strains observed included G1P[8] (38.8%), G9P[8] (20.4%), G2P[4] (12.2%), G3[P4] (6.1%), G2P[6] (4.1%), and G9P[6] (4.1%). Mixed genotype constellations G3P[4][8] were also detected (4.1%). Remarkably, an increased prevalence of G2 genotypes was observed, revealing a change in genetic diversity of rotavirus strains. While the dominance of G1P[8] decreased after vaccination, an upsurge in G2P[4] (12.2%) and G9P[8] (20.4%) was observed. Additionally, G3[P4] (6.1%) and G2P[6] (4.1%) prevalence increased over the 3 years of study.
Conclusions:
The results inform the need for robust longitudinal surveillance and epidemiological studies to assess the long-term interaction between rotavirus vaccine and strain ecology.
