Epidemiology of acute diarrhea caused by rotavirus in sentinel surveillance sites of Vietnam, 2016-2023

This study was conducted in four sentinel surveillance hospitals to describe the epidemiology of acute diarrhea caused by rotavirus and the molecular epidemiology among children under 5 years old in Vietnam. From 2016 to2023, a total of 14,647 stool specimens were collected for testing. 4,893 cases (33.4%) tested positive for rotavirus, in which 2,660 positive specimens were tested for genotype. The positive rate decreased gradually from 46.6% (2016) to 17.3% (2023). Although rotavirus was detected year-round, peak incidence occurred during the period from October to March. Positivity rates varied by age, highest in children aged 12–23 months (41.3%) and 24–59 months (36.5%). Rotavirus-positive children experienced an average of 7.8 episodes (95% CI: 7.7–7.9) diarrhea episodes within 24 hours and a higher rate of severe dehydration (4.7%) than rotavirus-negative children (7.4 episodes, 95% CI: 7.3–7.5; and 3.1%). Rotavirus infection and severe dehydration rates in the unvaccinated group were 35.2% and 5.1% higher than those in the vaccinated group (20.9% and 0.5%). The genotyping data revealed changes in variation of genotype distribution and in prevalent genotypes circulating over time: the co-dominance of variety of prevalent genotypes G1P[8], G2P[4], G3P[8], G8P[8], G9P[8] (2016–2021) was replaced by the predominance of G3P[8] (98%) (2022–2023). In conclusion, rotavirus infection remains a leading cause of acute diarrhea and severe dehydration among hospitalized children in Vietnam. Infection rate and variation in the genotype distribution of rotavirus tended to decrease. The introduction of the rotavirus vaccine into EPI could significantly reduce the burden of this disease.