The impact of rotavirus vaccination on acute diarrhea in Thai children under 5 years of age after the first year of universal implementation of rotavirus vaccines in the National Immunization Program (NIP) in Thailand: A 6-year analysis

Abstract

Background: Two types of rotavirus vaccines (RVs), Rotarix (RV1) and RotaTeq (RV5), were licensed as optional vaccines in 2012 and became part of the National Immunization Program (NIP) in 2020 in Thailand. The main objective was to evaluate the impact of rotavirus vaccines on the burden of acute diarrheal severity ranging from mild (outpatient department, OPD) to moderately severe as diarrheal-related admission or deaths in pre- and post-NIP periods. The minor objectives were assessed on the monthly admission rate, rotavirus vaccine coverage rate and rotavirus vaccine completed dose (RotaC). Methods: Data regarding OPD, admission, and death cases under the Thailand National Health Coverage (NHC) between 2015-2019 (pre-NIP period) and in 2020 as the post-NPI year, which were recorded as International Classification of Diseases and Related Health Problem 10th (ICD-10), were analyzed. Results: The burden of diarrheal-related disease was diminished after the rotavirus vaccine was introduced. The OPD visit rate decreased from 10.1 to 8.3 visits per 100 person-years pre- and post-NIP, respectively (P<0.001). The admission rate significantly declined from 31.4 to 30.5 cases per 1,000 person-years pre- and post-NIP, respectively (P<0.001). The diarrheal-related mortality rate also subsided from 10.2 to 8.1 cases per 100,000 person-years pre- and post-NIP, respectively (P 0.3). The major population in both admission and deaths was infants under 1 year of age (P<0.001). Seasonality was seen as a constant bimodal pattern for cool and rainy reasons. RotaC was as high as 37.4%, even in the first year of the NIP. Conclusions: The rotavirus vaccine had a great impact on the diarrheal disease burden of all outpatient visits, hospitalization, and mortality, especially in infants under one year of age. Seasonality outbreaks of acute diarrhea were observed in each examination year. The RotaC was high even in the first year of the NIP of the rotavirus vaccine. of rotavirus vaccine quality should be warranted. Trial registration: number TCTR20220120003, date of registration: 20/01/2022, site: Thai Clinical Trials Registry, URL https://www.thaiclinicaltrials.org/show/TCTR20220120003