Effectiveness and impact of monovalent rotavirus vaccination in Afghanistan: a test-negative case-control analysis.

ABSTRACT

BACKGROUND: Afghanistan introduced monovalent rotavirus vaccine (Rotarix) into its national immunisation schedule in January, 2018. While post-licensure studies have shown substantial declines in rotavirus gastroenteritis cases and deaths globally, there is little evidence of rotavirus vaccine effectiveness and impact from low-income countries in Asia. We aimed to evaluate the effectiveness of the Rotarix vaccine and the impact of Rotarix vaccine on rotavirus gastroenteritis hospitalisations (ie, hospital admissions) among children younger than 5 years in Afghanistan. METHODS: We used a test-negative case-control design embedded in an active sentinel surveillance platform to evaluate vaccine effectiveness. Children born on or after Jan 1, 2018, who had documentation of their rotavirus vaccination status and who were admitted for acute gastroenteritis at one of four sentinel hospitals from May, 2018 to December, 2021 were eligible to be included. We used an unconditional logistic regression model to estimate vaccine effectiveness and 95% CIs for a complete series of doses compared with no rotavirus vaccine doses among patients admitted with acute gastroenteritis. Vaccine effectiveness against hospitalisation was calculated as (1 - [odds of being vaccinated in cases] / [odds of being vaccinated in controls]) × 100%. We compared pre-vaccine (2013-15) and post-vaccine (2019-21) surveillance data from two sites to calculate vaccine impact. FINDINGS: The vaccine effectiveness analysis included 1172 cases and 2173 controls. Approximately 2108 (63·0%) of 3345 cases and controls were male, 1237 (37·0%) were female, and 2171 (65·0%) were aged 6-11 months. Two doses of Rotarix were 45% (95% CI 22-62) effective against rotavirus hospitalisation in children aged 6-59 months, adjusting for age, severity, admission year, and rotavirus season. Rotavirus positivity decreased from 51% pre-vaccine to 39% post-vaccine, resulting in a 39% adjusted reduction in rotavirus positivity among children younger than 5 years admitted with acute gastroenteritis. INTERPRETATION: Rotarix showed moderate effectiveness in preventing rotavirus gastroenteritis hospitalisations, consistent with findings in other low-income countries. These findings support the continued administration of the rotavirus vaccine in Afghanistan. FUNDING: Gavi, the Vaccine Alliance. TRANSLATION For the Dari translation of the abstract see Supplementary Materials section.