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August 13, 2018

Infant Diarrhea Deaths Drop Sharply in Malawi Due to Rotavirus Vaccine

Malawian children [Dr. Carina King]

  • An international team of researchers reports that rotavirus vaccination reduced infant diarrhea deaths by 34% in rural Malawi, a region with high levels of child deaths. 

    The study, led by scientists at the University of Liverpool, University College London, Johns Hopkins Bloomberg School of Public Health and partners in Malawi, provides the first population-level evidence from a low-income country that rotavirus vaccination saves lives, according to the researchers.

    The findings (“Impact of monovalent rotavirus vaccine on diarrhea-associated post-neonatal infant mortality in rural communities in Malawi: a population-based birth cohort study”) are published in The Lancet Global Health.

    “Rotavirus is a major contributor to child mortality. The effect of rotavirus vaccine on diarrhea mortality has been estimated in middle-income but not in low-income settings, where mortality is high and vaccine effectiveness in reducing admissions to hospital is lower. Empirical population-based mortality studies have not been done in any setting. Malawi introduced monovalent rotavirus vaccine (RV1) in October 2012. We aimed to investigate the impact and effectiveness of the RV1 vaccine in reducing diarrhea-associated mortality in infants aged 10–51 weeks,” write the investigators.

    “In this population-based cohort study, we included infants born between Jan 1, 2012, and June 1, 2015, in Mchinji, Central Malawi and analyzed data on those surviving 10 weeks. Individual vaccination status was extracted from caregiver-held records or report at home visits at four months and one year of age. Survival to one year was confirmed at home visit, or cause of death ascertained by verbal autopsy. We assessed the impact (1 minus mortality rate ratio following vs before vaccine introduction) using Poisson regression. Among vaccine-eligible infants (born from Sept 17, 2012), we assessed effectiveness (1 minus hazard ratio) using Cox regression.

    “Between Jan 1, 2012, and June 1, 2015, we recruited 48,672 live births in Mchinji, among whom 38,518 were vaccine-eligible and 37,570 survived to age 10 weeks. Two-dose versus zero-dose effectiveness analysis included 28,141 infants, of whom 101 had diarrhea-associated death before one year of age. Diarrhea-associated mortality declined by 31% (95% CI 1–52; p=0·04) after RV1 introduction. Effectiveness against diarrhea-mortality was 34% (95% CI –28 to 66; p=0·22).

    “RV1 was associated with substantial reduction in diarrhea-associated deaths among infants in this rural sub-Saharan African setting. These data add considerable weight to evidence showing the impact of rotavirus vaccine programs.”

    Nigel Cunliffe, Ph.D., professor of clinical infection, microbiology, and immunology at the University of Liverpool's Centre for Global Vaccine Research, says “Rotavirus remains a leading cause of severe diarrhea and death among infants and young children in many countries in Africa and Asia. Our findings strongly advocate for the incorporation of rotavirus vaccine into the childhood immunization programs of countries with high rates of diarrhea deaths, and support continued use in such countries where a vaccine has been introduced."

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