Effectiveness of a live oral human rotavirus vaccine after programmatic introduction in Bangladesh: A cluster-randomized trial.

K Zaman,Alejandro Cravioto,Firdausi Qadri,Ilias Hossain,Andrea J Feller,Kathleen M Neuzil,Lawrence H Moulton,Jonathan D Sugimoto,M Elizabeth Halloran,Tasnim Azim,Kristen D C Lewis,John C Victor,Shams El Arifeen,Jessica A Fleming,Mohammad Yunus,David A Sack,Mustafizur Rahman,James K Tumwine

doi:10.1371/journal.pmed.1002282

Abstract

BackgroundRotavirus vaccines are now globally recommended by the World Health Organization (WHO), but in early 2009 WHO’s Strategic Advisory Group of Experts on Immunization reviewed available data and concluded that there was no evidence for the efficacy or effectiveness of a two-dose schedule of the human rotavirus vaccine (HRV; Rotarix) given early at 6 and 10 wk of age. Additionally, the effectiveness of programmatic rotavirus vaccination, including possible indirect effects, has not been assessed in low-resource populations in Asia.Methods and findingsIn Bangladesh, we cluster-randomized (1:1) 142 villages of the Matlab Health and Demographic Surveillance System to include two doses of HRV with the standard infant vaccines at 6 and 10 wk of age or to provide standard infant vaccines without HRV. The study was initiated November 1, 2008, and surveillance was conducted concurrently at Matlab Diarrhoea Hospital and two community treatment centers to identify children less than 2 y of age presenting with acute rotavirus diarrhea (ARD) through March 31, 2011. Laboratory confirmation was made by enzyme immunoassay detection of rotavirus antigen in stool specimens. Overall effectiveness of the HRV vaccination program (primary objective) was measured by comparing the incidence rate of ARD among all children age-eligible for vaccination in villages where HRV was introduced to that among such children in villages where HRV was not introduced. Total effectiveness among vaccinees and indirect effectiveness were also evaluated. In all, 6,527 infants were age-eligible for vaccination in 71 HRV villages, and 5,791 in 71 non-HRV villages. In HRV villages, 4,808 (73.7%) infants received at least one dose of HRV. The incidence rate of ARD was 4.10 cases per 100 person-years in non-HRV villages compared to 2.8 per 100 person-years in HRV villages, indicating an overall effectiveness of 29.0% (95% CI, 11.3% to 43.1%). The total effectiveness of HRV against ARD among vaccinees was 41.4% (95% CI, 23.2% to 55.2%). The point estimate for total effectiveness was higher against ARD during the first year of life than during the second (45.2% versus 28.9%), but estimates for the second year of life lacked precision and did not reach statistical significance. Indirect effects were not detected. To check for bias in presentation to treatment facilities, we evaluated the effectiveness of HRV against acute diarrhea associated with enterotoxigenic Escherichia coli; it was 4.0% (95% CI, −46.5% to 37.1%), indicating that bias likely was not introduced. Thirteen serious adverse events were identified among recipients of HRV, but none were considered related to receipt of study vaccine. The main limitation of this study is that it was an open-label study with an observed-only control group (no placebo).ConclusionsThe two-dose HRV rotavirus vaccination program significantly reduced medically attended ARD in this low-resource population in Asia. Protection among vaccinees was similar to that in other low-resource settings. In low-resource populations with high rotavirus incidence, large-scale vaccination across a wide population may be required to obtain the full benefit of rotavirus vaccination, including indirect effects.Trial registrationClinicalTrials.gov NCT00737503

Highlights

Diarrhea continues to be a leading killer of children in low- and middle-income countries, and rotavirus has been shown to be the most common cause of moderate-to-severe diarrhea in infants and young children worldwide [1,2]
To check for bias in presentation to treatment facilities, we evaluated the effectiveness of human rotavirus vaccine (HRV) against acute diarrhea associated with enterotoxigenic Escherichia coli; it was 4.0%, indicating that bias likely was not introduced
In low-resource populations with high rotavirus incidence, large-scale vaccination across a wide population may be required to obtain the full benefit of rotavirus vaccination, including indirect effects

Summary

Introduction

Diarrhea continues to be a leading killer of children in low- and middle-income countries, and rotavirus has been shown to be the most common cause of moderate-to-severe diarrhea in infants and young children worldwide [1,2]. While current rotavirus vaccines have been found in individual-randomized trials conducted in populations with high child mortality to be about 40% to 60% efficacious (i.e., direct protection) against severe rotavirus gastroenteritis [4,5,6,12], large-scale programmatic introduction of rotavirus vaccine might reduce overall transmission of rotavirus and provide substantial indirect protection to those who remain unvaccinated. This indirect protection would improve the total protection for vaccinated infants, i.e., the combined protection conferred by the direct and indirect effects experienced by vaccinated children living in a vaccinated population [13]. The effectiveness of programmatic rotavirus vaccination, including possible indirect effects, has not been assessed in low-resource populations in Asia

Methods

Results

Conclusion