Continued Evidence of the Impact of Rotavirus Vaccine in Children Less Than 3 Years of Age From the United States New Vaccine Surveillance Network: A Multisite Active Surveillance Program, 2006-2016

Rotavirus genotypes and clinical outcome of natural infection based on vaccination status in the post-vaccine era

Rotavirus (RV) is a leading cause of gastroenteritis in children. In Japan, Rotarix (RV1; GlaxoSmithKline), which is a monovalent vaccine derived from human RV (G1P[8]), has been introduced since November 2011, and RotaTeq (RV5; MSD) which is an pentavalent, human-bovine mono-reassortant vaccine (G1, G2, G3, G4, and P1A[8]), has been introduced since July 2012. Long-term follow-up on vaccine efficacy and RV genotypical change should be carried out in order to control RV infection. The RV gastroenteritis (RVGE) outbreak occurred during the 2018/2019 season in Aichi prefecture, Japan. Therefore, the molecular epidemiology of RV among three different groups of RVGE, which were outpatients who received RV1, those who received RV5, and those without vaccination, was explored. Clinical features of RVGE patients were compared among the three patient groups. Children less than 15 years of age with gastroenteritis who visited any of seven pediatric practices between January and June 2019 were enrolled in the study. G, P, and E genotypes were determined by direct sequencing of reverse transcription-polymerase chain reaction products amplified from stool samples. Among 110 patients, there were 27, 28, and 55 in the RV1-vaccinated, RV5-vaccinated, and unvaccinated groups, respectively. The most frequent genotype was G8P[8] (92/110 patients, 83.6%). Genotype distributions did not significantly differ among the three patient groups (P = .125). Mean Vesikari score was significantly lower among RV1-vaccinated (7.1) and RV5-vaccinated patients (6.4) than among unvaccinated patients (10.2) (P < .001). Even in RVGE patients treated in an outpatient clinic, RV vaccine reduced the severity of the disease in this cohort.

Impact analysis of rotavirus vaccination in various geographic regions in Western Europe

BACKGROUND

Universal mass vaccination (UMV) against rotavirus has been implemented in many but not all European countries. This study investigated the impact of UMV on rotavirus incidence trends by comparing European countries with UMV: Belgium, England/Wales and Germany versus countries without UMV: Denmark and the Netherlands.

METHODS

For this observational retrospective cohort study, time series data (2001-2016) on rotavirus detections, meteorological factors and population demographics were collected. For each country, several meteorological and population factors were investigated as possible predictors of rotavirus incidence. The final set of predictors were incorporated in negative binomial models accounting for seasonality and serial autocorrelation, and time-varying incidence rate ratios (IRR) were calculated for each age group and country separately. The overall vaccination impact two years after vaccine implementation was estimated by pooling the results using a random effects meta-analyses. Independent t-tests were used to compare annual epidemics in the pre-vaccination and post-vaccination era to explore any changes in the timing of rotavirus epidemics.

RESULTS

The population size and several meteorological factors were predictors for the rotavirus epidemiology. Overall, we estimated a 42% (95%-CI 23;56%) reduction in rotavirus incidence attributable to UMV. Strongest reductions were observed for age-groups 0-, 1- and 2-years (IRR 0.47, 0.48 and 0.63, respectively). No herd effect induced by UMV in neighbouring countries was observed. In all UMV countries, the start and/or stop and corresponding peak of the rotavirus season was delayed by 4-7 weeks.

CONCLUSIONS

The introduction of rotavirus UMV resulted in an overall reduction of 42% in rotavirus incidence in Western European countries two years after vaccine introduction and caused a change in seasonal pattern. No herd effect induced by UMV neighbouring countries was observed for Denmark and the Netherlands.

Impact of rotavirus vaccine on admissions due to acute gastroenteritis and rotavirus gastroenteritis in Israel

AIM

We examined the impact of insertion of the Rotavirus vaccine (RVV) into the Israeli National Immunisation Programme (NIP) on hospitalisations due to both acute gastroenteritis (AGE) and Rotavirus gastroenteritis (RVGE) in children.

METHODS

We retrospectively analysed the medical records of children aged <5 years admitted with a diagnosis of AGE between 2008 and 2016 in two children's hospitals in central Israel. Clinical, laboratory, microbiological data and RV immunisation status were retrieved. Data were compared before and after the introduction of the RVV into the NIP.

RESULTS

A total of 2042 children were admitted with AGE. Hospitalisations due to AGE and RVGE decreased from 3310 to 1950 and from 1027 to 585 per 100 000 admissions, respectively, after the RVV (relative risk reduction (RRR) of 41% and 43%, respectively). RV remained the most common pathogen in both study periods. There was no significant difference in the clinical course between immunised and non-immunised children admitted with RVGE.

CONCLUSION

The introduction of the RVV to the NIP significantly reduced the admissions due to both AGE and RVGE in children <5 years. However, RV is still the most common agent for admissions due to AGE in this age group.