Infrequent Transmission of Monovalent Human Rotavirus Vaccine Virus to Household Contacts of Vaccinated Infants in Malawi.

Aisleen Bennett,Khuzwayo C Jere,Umesh Parashar,Virginia E Pitzer,Miren Iturriza-Gomara,Robert S Heyderman,Naor Bar-Zeev,Dean Everett,Nigel A Cunliffe,Louisa Pollock,Benjamin Lopman

doi:10.1093/infdis/jiz002

Abstract

Horizontal transmission of rotavirus vaccine virus may contribute to indirect effects of rotavirus vaccine, but data are lacking from low-income countries. Serial stool samples were obtained from Malawian infants who received 2 doses of monovalent human rotavirus vaccine (RV1) (days 4, 6, 8, and 10 after vaccination) and from their household contacts (8–10 days after vaccine). RV1 vaccine virus in stool was detected using semiquantitative real-time reverse-transcription polymerase chain reaction. RV1 fecal shedding was detected in 41 of 60 vaccinated infants (68%) and in 2 of 147 household contacts (1.4%). Horizontal transmission of vaccine virus within households is unlikely to make a major contribution to RV1 indirect effects in Malawi.

Highlights

Presented in part: African Rotavirus Symposium, Lilongwe, Malawi, 28th–30th May 2017; European Rotavirus Biology Meeting, Cork, Ireland, 18th–21st June 2017
Stool samples were collected from household contacts before administration of the first vaccine dose to the index infant and 8–10 days after administration of each vaccine dose
Wild-type rotavirus was detectable at baseline in 5 of 33 samples (15%; 95% confidence interval (CI), 6%–33%), with a median cycle threshold (Ct) value of 38.5

Summary

Introduction

Presented in part: African Rotavirus Symposium, Lilongwe, Malawi, 28th–30th May 2017; European Rotavirus Biology Meeting, Cork, Ireland, 18th–21st June 2017. Live oral rotavirus vaccines mimic natural infection, replicating in the gastrointestinal tract before being shed in stool. Several studies have demonstrated horizontal transmission of rotavirus vaccine virus from vaccinated infants to close contacts; reported transmission rates range from 0% to 18.8% [4,5,6]. The protective effects of horizontal transmission of vaccine virus to unvaccinated individuals has been well described for oral polio vaccine [7], but the role of such transmission in generating vaccine indirect effects for rotavirus is not established. We undertook a prospective cohort study in Malawi, a low-income African country with a high burden of rotavirus disease. We aimed to estimate the proportion of household contacts of RV1vaccinated infants who subsequently shed vaccine-type virus

Objectives

Methods

Results

Conclusion