Exceptionally low rotavirus incidence in the Netherlands in 2013/14 in the absence of rotavirus vaccination

Rotavirus Vaccine Safety and Effectiveness in Infants With High-Risk Medical Conditions

OBJECTIVES

Rotavirus vaccination has 87% to 100% effectiveness against severe rotavirus acute gastroenteritis (AGE) in healthy infants in high-income countries. Little is known whether infants with medical risk conditions (MRCs) are equally protected and if the vaccine is equally well tolerated. We conducted a quasi-experimental prospective multicenter before-after cohort study to assess the vaccine effectiveness (VE) and safety profile of the human rotavirus vaccine (HRV) among MRC infants that required prolonged or frequent postnatal care.

METHODS

The Netherlands has no national rotavirus immunization program, but HRV was implemented in routine care for MRC infants in 13 Dutch hospitals. Participants in the before and after cohort, HRV unvaccinated and vaccinated, respectively, were followed for occurrence of (rotavirus) AGE. VE of at least 1 dose was estimated by using time-to-event analysis for severe rotavirus AGE. Vaccine-related serious adverse event (AEs) after HRV were retrieved systematically from medical charts. Solicited AEs after vaccinations were prospectively collected and compared between vaccination time points with or without HRV.

RESULTS

In total, 1482 high-risk infants with MRC were enrolled, including 631 in the before and 851 in the after cohorts; 1302 infants were premature (88.3%), 447 were small for gestational age (30.2%), and 251 had at least 1 congenital disorder (17.0%). VE against severe rotavirus AGE was 30% (95% confidence interval [CI]: -36% to 65%). Overall, the observed number of rotavirus hospitalizations was low and not significantly different between the cohorts (2 and 2, respectively). The rate of vaccine-related serious AE was 0.24 per 100 vaccine doses. The adjusted risk ratio for any AE after HRV vaccination compared with other routine vaccinations was 1.09 (95% CI: 1.05 to 1.12) for concomitant administration and 0.91 (95% CI: 0.81 to 0.99) for single HRV administration. Gastrointestinal AEs were 10% more frequent after HRV.

CONCLUSIONS

In contrast to previous findings among healthy term infants, in routine use, HRV offered limited protection to vulnerable medical risk infants. HRV is generally well tolerated in this group in single administration, but when coadministered with routine vaccines, it is associated with higher risk of (mostly gastrointestinal) AE. Our study highlights the importance of studying vaccine performance in subgroups of medically vulnerable infants.

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.

Sustained declines in age group-specific rotavirus infection and acute gastroenteritis in vaccinated and unvaccinated individuals during the five years since Rotavirus vaccine introduction in England

BACKGROUND

The introduction of an oral live-attenuated monovalent rotavirus vaccine (Rotarix ®) into the UK infant immunisation programme in July 2013 was associated with large reductions in laboratory-confirmed rotavirus infections and hospitalisations due to acute gastroenteritis (AGE) within 12 months. Here we report the five-year impact of the programme in England.

METHODS

Individuals with laboratory-confirmed rotavirus infections during 2000-2018 and all-cause hospitalisations for AGE during 2007-2018 were identified using national electronic records. Age-specific incidence rate ratios (IRR) and estimated numbers of cases averted in each of the five post-vaccination years were calculated.

RESULTS

There were 206,389 laboratory-confirmed rotavirus infections and 3,657,651 hospitalisations for all-cause AGE. Reductions of 69-83% in laboratory-confirmed rotavirus infections in all age groups and 77-88% in infants aged <1 year in each of the five post-vaccine years are reported, with 11,386-11,633 cases averted annually. All-cause AGE hospitalisations were reduced by 12-35% across all age-groups and by 25-48% in <1 year-olds in the five post-vaccine years, with 24,474-49,278 hospitalisations averted annually. There was strong evidence of indirect (herd) protection, with at least 50% and up to 80% of the non-specific end point of all-cause gastroenteritis (AGE) hospitalisations averted being in unvaccinated age-groups, primarily older adults. Seasonal changes include a possible shift from annual to biennial peaks with lower peak incidence and longer seasons.

CONCLUSIONS

There were large and sustained declines in both laboratory-confirmed rotavirus infections and AGE hospitalisations across all age groups in each of the five years since the introduction of the UK rotavirus programme.

Impact of the Rotavirus Vaccination Program in Norway After Four Years With High Coverage

BACKGROUND

Use of rotavirus vaccines worldwide since 2006 has led to a significant impact on the burden of rotavirus disease. However, only a third of European countries have introduced rotavirus vaccination in their immunization programs. In October 2014, rotavirus vaccination was introduced for Norwegian infants under strict age restrictions. Exclusive use of the monovalent rotavirus vaccine (RV1) and high vaccination coverage from the beginning enabled evaluation of the impact of this vaccine during the first 4 years after introduction.

METHODS

Prospective laboratory-based surveillance among children <5 years of age hospitalized for acute gastroenteritis at 5 Norwegian hospitals was used to assess the vaccine effectiveness of 2 vaccine doses against rotavirus hospitalization in a case-control study. We used community controls selected from the national population-based immunization registry, and test-negative controls recruited through hospital surveillance. We also assessed the vaccine impact by using time-series analysis of retrospectively collected registry data on acute gastroenteritis in primary and hospital care during 2009-2018.

RESULTS

Vaccine effectiveness against rotavirus-confirmed hospitalization was 76% (95% confidence interval [CI]: 34%-91%) using test-negative controls, and 75% (95% CI: 44%-88%) using community controls. In the postvaccine period, acute gastroenteritis hospitalizations in children <5 years were reduced by 45% compared with the prevaccine years (adjusted incidence rate ratios 0.55; 95% CI: 0.49-0.61). Reduction in hospitalizations was also seen in cohorts not eligible for vaccination. Rates in primary care decreased to a lesser degree.

CONCLUSIONS

Four years after introduction of rotavirus vaccination in the national childhood immunization program, we recorded a substantial reduction in the number of children hospitalized for acute gastroenteritis in Norway, attributable to a high vaccine effectiveness.

Acute Gastroenteritis Disease Burden in Infants With Medical Risk Conditions in the Netherlands

BACKGROUND

Infants with medical risk conditions are vulnerable to childhood infections including acute gastroenteritis (AGE). To guide prevention programs, we quantified AGE incidence, severity and virus prevalence among medical risk infants in the Netherlands.

METHODS

This prospective cohort-study was part of the RIVAR-project recruiting infants with prematurity, low birth weight or severe congenital conditions in 13 hospitals. Follow-up included 18 monthly health questionnaires detailing AGE symptoms and healthcare usage. Parents were also instructed to notify when an infant developed AGE, to collect a stool sample and complete a daily severity score (Modified Vesikari Severity). Stool samples were analyzed by real-time polymerase chain reaction for rotavirus, norovirus, adenovirus and astrovirus.

RESULTS

Between November 2014 and October 2017, 631 infants participated during 9125 person-months of observation. In total, 559 episodes were identified. The mean AGE incidence rate was 73.5 per 100 person-years (PY) (95% confidence interval: 67.6-79.9) and increased with age [incidence rate: 48.3 (39.8-58.3) vs. 80.2 (73.0-88.1)/100 PY for ages 1-5 vs. 6-18 months, respectively]. Healthcare was attended for 38.1% (213/559) and 26.8% (68/254) were classified as severe based on the Modified Vesikari Severity. Stool samples were obtained from 254 AGE episodes. Norovirus was identified in 65 (25.6%) and rotavirus in 44 (17.7%). Adenovirus and astrovirus together accounted for 8.3% (N = 21). Severe AGE occurred most frequently in rotavirus positive episodes.

CONCLUSION

The observed AGE incidence, severity and healthcare usage among medical risk infants confirms substantial disease burden. Norovirus and rotavirus are the dominant pathogens and severe episodes occurred most frequently in children with rotavirus infection. AGE prevention in medical risk infants should be prioritized.

The impact of publicly funded rotavirus immunization programs on Canadian children

Background

In 2008, the National Advisory Committee on Immunization recommended routine rotavirus immunizations in healthy Canadian infants. Over the following seven years, eight provinces and two territories introduced the rotavirus vaccine into their publicly funded immunization programs.

Objective

Assess the burden of rotavirus infections before and after implementation of publicly funded immunization programs.

Methods

We analyzed laboratory-confirmed community cases of rotavirus reported to the National Enteric Surveillance Program and hospitalizations of children younger than three years old from 2007 to 2017 with rotavirus diagnosis-specific ICD-10 codes. Rates of illness were calculated for each province for the two years prior to and after implementation of public funding of the vaccine. The year of implementation was not included to accommodate the uptake period of the vaccine. Age-specific rates were assessed in jurisdictions where five years of data were available the year after the vaccine was publicly funded. The pre-post and difference-in-difference (DID) methodologies were applied to hospital discharge data to evaluate changes between the funding and non-funding jurisdictions.

Results

Community cases of laboratory-confirmed rotavirus infection reported to the National Enteric Surveillance Program declined by 54% between 2010 and 2017. Rates of hospital discharges decreased significantly among children in six provinces after the adoption of the rotavirus vaccine. Hospital discharge rates in Alberta, Manitoba, Ontario and Prince Edward Island dropped between 53% and 71%, and by 75% for British Columbia and Saskatchewan.

Conclusion

Public funding of the rotavirus vaccine appeared to lead to significant reductions in laboratory-confirmed rotavirus cases reported to the National Enteric Surveillance Program and in the rates of rotavirus gastroenteritis-related hospital discharges.

Using emergency department syndromic surveillance to investigate the impact of a national vaccination program: A retrospective observational study

Background

Rotavirus infection is a common cause of gastroenteritis in children worldwide, with a high mortality burden in developing countries, particularly during the first two years of life. Rotavirus vaccination was introduced into the United Kingdom childhood vaccination schedule in July 2013, with high coverage (>90%) achieved by June 2016. We used an emergency department (ED) syndromic surveillance system to assess the impact of the rotavirus vaccination programme, specifically through the demonstration of any immediate and continuing impact on ED gastroenteritis visits in England.

Methods

This retrospective, observational study used syndromic surveillance data collected from 3 EDs in the two years before (July 2011—June 2013) and 3 years post (July 2013—June 2016) introduction of rotavirus vaccination. The weekly levels of ED visits for gastroenteritis (by age group and in total) during the period before rotavirus vaccination was first described alongside the findings of laboratory surveillance of rotavirus during the same period. An interrupted time-series analysis was then performed to demonstrate the impact of rotavirus vaccination introduction on gastroenteritis ED visit levels.

Results

During the two years before vaccine introduction ED visits for gastroenteritis in total and for the 0–4 years age group were seen to rise and fall in line with the seasonal rotavirus increases reported by laboratory surveillance. ED gastroenteritis visits by young children were lower in the three years following introduction of rotavirus vaccination (reduced from 8% of visits to 6% of visits). These attendance levels in young children (0-4years) remained higher than in older age groups, however the previously large seasonal increases in children were greatly reduced, from peaks of 16% to 3–10% of ED visits per week.

Conclusions

ED syndromic surveillance demonstrated a reduction in gastroenteritis visits following rotavirus vaccine introduction. This work establishes ED syndromic surveillance as a platform for rapid impact assessment of future vaccine programmes.

Referral rates for children with acute gastroenteritis: a retrospective cohort study

Background

Hospital admission rates are increasing for children with acute gastroenteritis. However, it is unknown whether this increase is accompanied by an increase in referral rates from GPs due to increased workloads in primary care out-of-hours (OOH) services.

Aim

To assess trends in referral rates from primary care OOH services to specialist emergency care for children presenting with acute gastroenteritis.

Design & setting

This retrospective cohort study covered a period from September 2007–September 2014. Children aged 6 months to 6 years presenting with acute gastroenteritis to a primary care OOH service were included.

Method

Pseudonymised data were obtained, and children were analysed overall and by age category. Χ² trend tests were used to assess rates of acute gastroenteritis, referrals, face-to-face contacts, and oral rehydration therapy (ORT) prescriptions.

Results

The data included 12 455 children (6517 boys), with a median age of 20.2 months (interquartile range [IQR] 11.6 to 36.0 months). Over 7 years, incidence rates of acute gastroenteritis decreased significantly, and face-to-face contact rates increased significantly (both, P<0.01). However, there was no significant trend for referral rates (P = 0.87) or prescription rates for ORT (P = 0.82). Subgroup analyses produced comparable results, although there was an increase in face-to-face contact rates for the older children.

Conclusion

Incidence rates for childhood acute gastroenteritis presenting in OOH services decreased and referral rates did not increase significantly. These findings may be useful as a reference for the impact of new interventions for childhood acute gastroenteritis.

Rotavirus gastroenteritis hospitalization rates and correlation with rotavirus vaccination coverage in Sicily

Background and aim of the works:Rotavirus (RV) is considered the main cause of gastroenteritis in children from 0 to 59 months and vaccination represents the only strategy to prevent hospitalizations due to RV. In 2013 Sicilian Region introduced universal RV vaccination for all newborns. The present study aims to estimate the reduction rotavirus gastroenteritis (RVGE) hospitalization rates among Sicilian children and their relations with vaccination coverages of the nine Sicilian Local Health Units (LHUs). Methods: Were analyzed hospital discharge records including a diagnosis of RVGE occurred from January 2009 to December 2017 in hospitalized children aged 0 to 59 months, residents in Sicily. Were reported data on complete RV vaccination cycles among Sicilian children under 12 months of age (vaccination coverage). Results: A 49.2% overall reduction of RVGE hospitalization rates was reported after RV vaccination introduction. A more considerable reduction of hospitalization rates was observed among children aged 0 to 11 months (-61.4%), followed by children aged 12-23 months (-51.2%) and 24-35 months (-48.8%). In all the nine Sicilian Local Health Units (LHUs), a reduction of RVGE hospitalization rates was observed after RV vaccine implementation. Conclusions: This study demonstrated the significant impact of RV vaccination on RVGE hospitalization rates in Sicily, especially among children aged 0 to 23 months. The reduction in RVGE hospitalization rates observed in the Sicilian LHUs after universal vaccination program implementation, were generally higher or consistent with average vaccination coverage reported from 2013 to 2017. (www.actabiomedica.it)

Updated cost-effectiveness and risk-benefit analysis of two infant rotavirus vaccination strategies in a high-income, low-endemic setting

BACKGROUND AND OBJECTIVE

Since 2013, a biennial rotavirus pattern has emerged in the Netherlands with alternating high and low endemic years and a nearly 50% reduction in rotavirus hospitalization rates overall, while infant rotavirus vaccination has remained below 1% throughout. As the rotavirus vaccination cost-effectiveness and risk-benefit ratio in high-income settings is highly influenced by the total rotavirus disease burden, we re-evaluated two infant vaccination strategies, taking into account this recent change in rotavirus epidemiology.

METHODS

We used updated rotavirus disease burden estimates derived from (active) surveillance to evaluate (1) a targeted strategy with selective vaccination of infants with medical risk conditions (prematurity, low birth weight, or congenital conditions) and (2) universal vaccination including all infants. In addition, we added herd protection as well as vaccine-induced intussusception risk to our previous cost-effectiveness model. An age- and risk-group structured, discrete-time event, stochastic multi-cohort model of the Dutch pediatric population was used to estimate the costs and effects of each vaccination strategy.

RESULTS

The targeted vaccination was cost-saving under all scenarios tested from both the healthcare payer and societal perspective at rotavirus vaccine market prices (€135/child). The cost-effectiveness ratio for universal vaccination was €51,277 at the assumed vaccine price of €75/child, using a societal perspective and 3% discount rates. Universal vaccination became cost-neutral at €32/child. At an assumed vaccine-induced intussusception rate of 1/50,000, an estimated 1707 hospitalizations and 21 fatal rotavirus cases were averted by targeted vaccination per vaccine-induced intussusception case. Applying universal vaccination, an additional 571 hospitalizations and <  1 additional rotavirus death were averted in healthy children per vaccine-induced intussusception case.

CONCLUSION

While universal infant rotavirus vaccination results in the highest reductions in the population burden of rotavirus, targeted vaccination should be considered as a cost-saving alternative with a favorable risk-benefit ratio for high-income settings where universal implementation is unfeasible because of budget restrictions, low rotavirus endemicity, and/or public acceptance.

Biennial Pattern of Rotavirus Gastroenteritis in The Netherlands and a Shifting Age Distribution After a Low Rotavirus Season, 2010-2016

A hyperendemic rotavirus season was expected after a low-endemic 2014 season in the Netherlands. Rotavirus detections were however similar in 2015 and lower in 2016 compared with 2010-2013. Gastroenteritis consultation rates were also similar in 2015, but the age distribution shifted to older children because of an accumulation of noninfected children. Results indicate a possible shift to a biennial rotavirus pattern.

Universal rotavirus vaccination program in Sicily: Reduction in health burden and cost despite low vaccination coverage

Rotavirus is considered the main cause of severe gastroenteritis and nosocomial infections in Pediatric units, especially during late winter and early spring season in temperate region. In 2013 Sicilian Region, for the first time in Italy, introduced universal Rotavirus vaccination. This study aims to estimate health and economic impact on rotavirus Gastroenteritis (RVGE) among children aged 0–59 months in Sicily, after rotavirus vaccine introduction.

We analyzed hospital discharge records including a diagnosis of RVGE occurred from 1^st January 2009 to 31^st December 2016 among hospitalized children aged 0 to 59 months, residents in Sicily. RVGEs were defined as all hospitalizations with an ICD-9-CM diagnosis code of 008.61 on first or any diagnosis position. Also an economic impact analysis on Health Regional System was conducted.

We observed a consistent decline of hospitalization after rotavirus vaccination introduction from 394 per 100,000 in 2009–2012 to 220 per 100,000 in 2013–2016. We found a change in the peak of reported cases by at least one month from March-April in the pre-vaccination period to May-June in the post-vaccination period. Since 2013, we estimated that the annual average cost saved is 1,134,056 € when considering direct and indirect costs to health care as well as vaccination costs.

Our study is the first analysis conducted as far as we are aware in a high-income setting with poor coverage (lower than 50%), demonstrating a significant reduction of RVGE hospitalizations in Sicily after vaccine introduction. Moreover, was observed a consistent impact of vaccination on health care cost saving.

Secular trends in incidence of acute gastroenteritis in general practice, France, 1991 to 2015

We analysed 25 years of general practitioner (GP) visits for acute gastroenteritis (AG) surveillance in France, by the GP Sentinelles network. We searched for time trends of acute gastroenteritis incidence during winter periods. Data from emergency departments and drug reimbursement were additional data sources. A time-series analysis was performed using a generalised additive model for all data sources for the winter period. Virological data were incorporated and compared with the three data sources. The cumulative incidence of GP visits for winter AG exhibited an increasing trend from 1991 until 2008, when it reached 6,466 per 100,000 inhabitants. It decreased thereafter to 3,918 per 100,000 inhabitants in 2015. This decreasing trend was observed for all age groups and confirmed by the generalised additive model. For emergency department visits a decreasing trend was observed from 2004. Drug reimbursement data analyses demonstrated a decreasing trend from when data began in 2009. The incidence reported by GPs and emergency departments was lower following the emergence of norovirus GII.4 2012 (p < 0.0001). Winter AG incidences seem to follow long-term rising and decreasing trends that are important to monitor through continuous surveillance to evaluate the impact of prevention strategies, such as future immunisation against acute viral gastroenteritis.

Determinants of Rotavirus Transmission: A Lag Nonlinear Time Series Analysis

Supplemental Digital Content is available in the text.

Rotavirus is a common viral infection among young children. As in many countries, the infection dynamics of rotavirus in the Netherlands are characterized by an annual winter peak, which was notably low in 2014. Previous study suggested an association between weather factors and both rotavirus transmission and incidence. From epidemic theory, we know that the proportion of susceptible individuals can affect disease transmission. We investigated how these factors are associated with rotavirus transmission in the Netherlands, and their impact on rotavirus transmission in 2014. We used available data on birth rates and rotavirus laboratory reports to estimate rotavirus transmission and the proportion of individuals susceptible to primary infection. Weather data were directly available from a central meteorological station. We developed an approach for detecting determinants of seasonal rotavirus transmission by assessing nonlinear, delayed associations between each factor and rotavirus transmission. We explored relationships by applying a distributed lag nonlinear regression model with seasonal terms. We corrected for residual serial correlation using autoregressive moving average errors. We inferred the relationship between different factors and the effective reproduction number from the most parsimonious model with low residual autocorrelation. Higher proportions of susceptible individuals and lower temperatures were associated with increases in rotavirus transmission. For 2014, our findings suggest that relatively mild temperatures combined with the low proportion of susceptible individuals contributed to lower rotavirus transmission in the Netherlands. However, our model, which overestimated the magnitude of the peak, suggested that other factors were likely instrumental in reducing the incidence that year.

Sustained low rotavirus activity and hospitalisation rates in the post-vaccination era in Belgium, 2007 to 2014

In 2006, Belgium was the first country in the European Union to recommend rotavirus vaccination in the routine infant vaccination schedule and rapidly achieved high vaccine uptake (86-89% in 2007). We used regional and national data sources up to 7 years post-vaccination to study the impact of vaccination on laboratory-confirmed rotavirus cases and rotavirus-related hospitalisations and deaths. We showed that (i) from 2007 until 2013, vaccination coverage remained at 79-88% for a complete course, (ii) in children 0-2 years, rotavirus cases decreased by 79% (95% confidence intervals (CI): 68--89%) in 2008-2014 compared to the pre-vaccination period (1999--2006) and by 50% (95% CI: 14-82%) in the age group ≥ 10 years, (iii) hospitalisations for rotavirus gastroenteritis decreased by 87% (95% CI: 84-90%) in 2008--2012 compared to the pre-vaccination period (2002--2006), (iv) median age of rotavirus cases increased from 12 months to 17 months and (v) the rotavirus seasonal peak was reduced and delayed in all post-vaccination years. The substantial decline in rotavirus gastroenteritis requiring hospitalisations and in rotavirus activity following introduction of rotavirus vaccination is sustained over time and more pronounced in the target age group, but with evidence of herd immunity.

Impact of the national rotavirus vaccination programme on acute gastroenteritis in England and associated costs averted

BACKGROUND

Introduction of infant oral rotavirus vaccination in the UK in July 2013 has resulted in decreased hospitalisations and Emergency Department (ED) visits for acute gastroenteritis (AGE), for both adults and children. We investigated reductions in AGE incidence seen in primary care in the two years after vaccine introduction, and estimated the healthcare costs averted across healthcare settings in the first year of the vaccination programme.

METHODS

We used primary care data from the Clinical Practice Research Datalink and age-stratified time-series analyses to derive adjusted incidence rate ratios (IRR_a) for AGE in the first two years of the post-vaccination era (July 2013-April 2015) compared to the pre-vaccination era (July 2008-June 2013). We estimated cases averted among children aged <5years in the first year of the vaccination programme by comparing observed numbers of AGE cases in 2013-2014 to numbers predicted from the time-series models. We then estimated the healthcare costs averted for general practice consultations, ED visits and hospitalisations.

RESULTS

In general practice, AGE rates in infants (the target group for vaccination) decreased by 15% overall after vaccine introduction (IRR_a=0.85; 95%CI=0.76-0.95), and by 41% in the months of historically high rotavirus circulation (IRR_a=0.59; 95%CI=0.53-0.66). Rates also decreased in other young children and to a lesser degree in older individuals, indicating herd immunity. Across all three settings (general practice, EDs, and hospitalisations) an estimated 87,376 (95% prediction interval: 62,588-113,561) AGE visits by children aged <5years were averted in 2013-14, associated with an estimated £12.5million (9,209-16,198) reduction in healthcare costs.

CONCLUSIONS

The marked decreases in the general practice AGE burden after rotavirus vaccine introduction mirror decreases seen in other UK healthcare settings. Overall, these decreases are associated with substantial averted healthcare costs.

Characteristics of child daycare centres associated with clustering of major enteropathogens

Insights into transmission dynamics of enteropathogens in children attending daycare are limited. Here we aimed at identifying daycare centre (DCC) characteristics associated with time-clustered occurrence of enteropathogens in DCC-attending children. For this purpose, we used the KIzSS network, which comprises 43 DCCs that participated in infectious disease surveillance in The Netherlands during February 2010-February 2013. Space-time scan statistics were used to identify clusters of rotavirus, norovirus, astrovirus, Giardia lamblia and Cryptosporidium spp. in a two-dimensional DCC characteristic space constructed using canonical correlation analysis. Logistic regression models were then used to further identify DCC characteristics associated with increased or decreased odds for clustering of enteropathogens. Factors associated with increased odds for enteropathogen clustering in DCCs were having indoor/outdoor paddling pools or sandpits, owning animals, high numbers of attending children, and reporting outbreaks to local health authorities. Factors associated with decreased odds for enteropathogen clustering in DCCs were cleaning child potties in designated waste disposal stations, cleaning vomit with chlorine-based products, daily cleaning of toys, extra cleaning of toys during a suspected outbreak, and excluding children with gastroenteritis. These factors provide targets for reducing the burden of gastrointestinal morbidity associated with time-clustered occurrence of major enteropathogens in DCC attendees.

Epidemiological trends for hospital admissions for acute rotavirus gastroenteritis in Belgium following the introduction of routine rotavirus vaccination and the subsequent switch from lyophilized to liquid formulation of Rotarix™

This study describes epidemiological trends for acute rotavirus gastroenteritis (RVGE) in Belgium in children aged ⩽5 years during the period June 2007 to May 2014 after the introduction of routine rotavirus (RV) vaccination. This period encompassed the switch from lyophilized to the liquid formulation of Rotarix™ (GlaxoSmithKline, Belgium) in August 2011. Uptake of RV vaccine remained consistently high throughout the study period with Rotarix the brand most often used. RV was present in 9% (1139/12 511) of hospitalized cases with acute gastroenteritis included in the study. Epidemiological trends for hospital admissions for RVGE remained consistent throughout the study period, with no evidence of any change associated with the switch from lyophilized to liquid formulation of Rotarix. This suggests both formulations perform similarly, with the liquid formulation not inferior regarding ability to reduce hospital admissions for acute RVGE in children aged ⩽5 years. A strong seasonal effect was observed with most RVGE occurring in the winter months but with some variability in intensity, with highest incidence found in those aged 6–24 months. The main observation was the decreased number of hospital admissions for RVGE in Belgium that occurred during winter 2013/2014.

Marked Decrease in Rotavirus Detections Among Preschool Children Unvaccinated for Rotavirus in the Netherlands, 2014

Rotavirus detection rates among preschool children sampled irrespective of symptoms during the rotavirus season (January-April) in the Netherlands were significantly lower in 2014 (0.6%) than in 2010 (11.2%), 2011 (6.9%), 2012 (6.8%) and 2013 (6.7%). This supports previous observations of a genuine drop in rotavirus circulation (without rotavirus vaccination) rather than a milder disease course.

Introduction of a new Rotavirus vaccine: Initial results of uptake and impact on laboratory confirmed cases in Anglia and Essex, United Kingdom, July 2015

Rotavirus gastroenteritis accounts for an estimated 130,000 GP consultations and 13,000 hospitalisations for children under 5 y old each year in England and Wales. In July 2013, an oral live attenuated rotavirus vaccine (Rotarix®) was introduced into the UK infant immunisation program as a 2 dose schedule at 2 and 3 months of age. We collected vaccination uptake from October 2013 to March 2015 and laboratory confirmed cases data on children under the age of 5 y from 1 January 2004 to 31 May 2015. The vaccine uptake rates and laboratory confirmed cases were compared to provide evidence of the impact of this vaccination program. Vaccine uptake rates were available from sentinel data with between 91-98% of GP practices in Anglia and Essex providing data every month. These data showed from February 2014 to March 2015 between 90-92% of infants received the recommended 2 doses of Rotarix® each month. The numbers of rotavirus cases reported by laboratories decreased on average by 82% in the post vaccination seasons. The mean number of cases reported in weeks 1-22 for 2004-2013 in Anglia and Essex was 1,318. For the same period in 2014, 256 cases were reported and initial data for 2015 report 226 cases. In the first 5 months 2014 the greatest reduction in cases (89%) was seen in those under 1 yr (who would have been directly affected by vaccination) with case numbers falling to 59 from a mean 537 cases in the equivalent period for 2004-2013. Initially data suggests a 92% reduction in 2015 compared to the same pre-vaccination periods. For those aged 1 to <5 y who would not have been vaccinated, a reduction of 75% was also evident in 2014 and 77% in 2015, suggesting indirect protection in this group. In conclusion, initial results following the introduction of the Rotavirus vaccine clearly indicates a very good uptake of the vaccine and a significant reduction in the numbers of laboratory confirmed cases.

Did Large-Scale Vaccination Drive Changes in the Circulating Rotavirus Population in Belgium?

Vaccination can place selective pressures on viral populations, leading to changes in the distribution of strains as viruses evolve to escape immunity from the vaccine. Vaccine-driven strain replacement is a major concern after nationwide rotavirus vaccine introductions. However, the distribution of the predominant rotavirus genotypes varies from year to year in the absence of vaccination, making it difficult to determine what changes can be attributed to the vaccines. To gain insight in the underlying dynamics driving changes in the rotavirus population, we fitted a hierarchy of mathematical models to national and local genotype-specific hospitalization data from Belgium, where large-scale vaccination was introduced in 2006. We estimated that natural- and vaccine-derived immunity was strongest against completely homotypic strains and weakest against fully heterotypic strains, with an intermediate immunity amongst partially heterotypic strains. The predominance of G2P[4] infections in Belgium after vaccine introduction can be explained by a combination of natural genotype fluctuations and weaker natural and vaccine-induced immunity against infection with strains heterotypic to the vaccine, in the absence of significant variation in strain-specific vaccine effectiveness against disease. However, the incidence of rotavirus gastroenteritis is predicted to remain low despite vaccine-driven changes in the distribution of genotypes.

Assessing the impacts of the first year of rotavirus vaccination in the United Kingdom

The United Kingdom (UK) added rotavirus (RV) vaccine (Rotarix GlaxoSmithKline) to the national vaccine schedule in July 2013. During the 2012–2014 rotavirus seasons, children presenting to the Bristol Royal Hospital for Children Emergency Department with gastroenteritis symptoms had stool virology analysis (real-time PCR) and clinical outcome recorded. Nosocomial cases were identified as patients with non-gastroenteritis diagnosis testing positive for rotavirus > 48h after admission. In comparison to average pre-vaccine seasons, in the first year after vaccine introduction there were 48% fewer attendances diagnosed with gastroenteritis, 53% reduction in gastroenteritis admissions and a total saving of 330 bed-days occupancy. There was an overall reduction in number of rotavirus-positive stool samples with 94% reduction in children aged under one year and a 65% reduction in those too old to have been vaccinated. In the first year after the introduction of universal vaccination against rotavirus we observed a profound reduction in gastroenteritis presentations and admissions with a substantial possible herd effect seen in older children. Extrapolating these findings to the UK population we estimate secondary healthcare savings in the first year of ca £7.5 (€10.5) million. Ongoing surveillance will be required to determine the long-term impact of the RV immunisation programme.

Rapid Declines in Age Group-Specific Rotavirus Infection and Acute Gastroenteritis Among Vaccinated and Unvaccinated Individuals Within 1 Year of Rotavirus Vaccine Introduction in England and Wales

BACKGROUND

The oral infant rotavirus vaccine, Rotarix, was introduced in England and Wales in July 2013. We estimated the impact on laboratory-confirmed rotavirus infections and hospitalizations for all-cause acute gastroenteritis (AGE) during the first year after introduction.

METHODS

We extracted data on laboratory-confirmed rotavirus infections (July 2000 through June 2015) and all-cause AGE-associated hospitalizations (July 2007 through June 2014) for all age groups using national databases (LabBase2 and HES). We determined the ratio of the rate during the 2013-2014 rotavirus season to the rate during the prevaccination era.

RESULTS

In infants, there was a 77% decline (rate ratio [RR], 0.23; 95% confidence interval [CI], .16-.32) in laboratory-confirmed rotavirus infections and a 26% decline (RR, 0.74; 95% CI, .65-.84) in all-cause AGE-associated hospitalizations in 2013-2014, compared with the prevaccination era. Large reductions were also observed in older children, adults, and older adults. We estimated that 10 884 laboratory-confirmed infections and 50 427 all-cause AGE-associated hospital admissions were averted in 2013-2014. Similar reductions have been observed for laboratory-confirmed rotavirus infections during the 2014-2015 season.

CONCLUSIONS

The rapid declines in rotavirus infection and AGE in vaccinated and unvaccinated age groups within 1 year of introducing an infant rotavirus vaccination program are far greater than expected and than previously reported by other countries.