Rotavirus vaccine effective for prevention of acute gastroenteritis

Mónica López-Lacort and team used a new spatiotemporal method to assess rotavirus vaccine effectiveness in preventing acute gastroenteritis, highlighting potential indirect protection effects and their impact on direct vaccine effectiveness (VE) estimates.

Using electronic healthcare registries, a population-based retrospective cohort study comprising children aged 2 months to 5 years (born between 2009 and 2018) in Spain was analyzed. A statistical analysis was conducted to estimate the direct VE of RV against AGE-PC episodes, using propensity score matching and Poisson regression models, with adjustments made for age and calendar season, and stratification by VC. Poisson regression was used to estimate indirect VE by comparing acute gastroenteritis primary care rates in unvaccinated children at different levels of VC.

The study population comprised 563,442 children, with 360,576 of them forming the birth cohort for the vaccine effectiveness analysis. The rates of vaccine coverage for RV varied meaningfully across districts and seasons, with an increase from 21% in the 2009/2010 period to 55% in the 2017/2018 period.

Children from districts with lower vaccination coverage rates (0-30%) showed a significantly higher VE of 16.4%, compared to those from districts with higher vaccination coverage rates of more than equal to 70%, where the VE was 9.7%. The percentage of indirect protection in unvaccinated children increased to 16.6% from a mere 6% among those living in areas with ≥70% and 20–30% vaccine coverage.