Population-Level Impact of Ontario's Infant Rotavirus Immunization Program: Evidence of Direct and Indirect Effects

Systematic review of rotavirus vaccination cost-effectiveness in high income settings utilising dynamic transmission modelling techniques

PURPOSE

This systematic review presents cost-effectiveness studies of rotavirus vaccination in high-income settings based on dynamic transmission modelling to inform policy decisions about implementing rotavirus vaccination programmes.

METHODS

We searched CEA Registry, MEDLINE, Embase, Health Technology Assessment Database, Scopus, and the National Health Service Economic Evaluation Database for studies published since 2002. Full economic evaluation studies based on dynamic transmission models, focusing on high-income countries, live oral rotavirus vaccine and children ≤ 5 years of age were eligible for inclusion. Included studies were appraised for quality and risk of bias using the Consensus on Health Economic Criteria (CHEC) list and the Philips checklist. The review protocol was prospectively registered with PROSPERO (CRD42020208406).

RESULTS

A total of four economic evaluations were identified. Study settings included England and Wales, France, Norway, and the United States. All studies compared either pentavalent or monovalent rotavirus vaccines to no intervention. All studies were cost-utility analyses that reported incremental cost per quality-adjusted life year (QALY) gained. Included studies consistently concluded that rotavirus vaccination is cost-effective compared with no vaccination relative to the respective country's willingness to pay threshold when herd protection benefits are incorporated in the modelling framework.

CONCLUSIONS

Rotavirus vaccination was found to be cost-effective in all identified studies that used dynamic transmission models in high-income settings where child mortality rates due to rotavirus gastroenteritis are close to zero. Previous systematic reviews of economic evaluations considered mostly static models and had less conclusive findings than the current study. This review suggests that modelling choices influence cost-effectiveness results for rotavirus vaccination. Specifically, the review suggests that dynamic transmission models are more likely to account for the full impact of rotavirus vaccination than static models in cost-effectiveness analyses.

Сost-effectiveness of pentavalent rotavirus vaccination in the Russian Federation

   One of the main causes of acute gastroenteritis in children under 5 years of age is rotavirus infection (RVI). Vaccines against RVI significantly reduce the incidence.   Aim. To evaluate the cost-effectiveness of mass vaccination of children with a 5-valent RVI vaccine in the Russian Federation.   Materials and methods. The assessment was carried out using modeling based on published data on the effectiveness of the vaccine and epidemiological indicators in the Russian Federation. The analysis was carried out from the perspective of the health care system and society as a whole with a 5-year horizon. The cost of RVI therapy corresponded to the compulsory health insurance tariffs for St. Petersburg for 2022, the price of 1 dose of the vaccine was the registered price, including VAT. Costs and life expectancy, taking into account quality, were discounted at 3.5 % per year.   Results. Given the assumptions made, routine vaccination will prevent an average of 468,637 cases of RVI over 5 years. Avoided direct medical costs, i. e. RVI treatment costs will amount to 53,4 %, and lost income due to temporary disability – 46,6 % of the total avoided costs. At the same time, the volume of avoided costs is 61,4 % due to a decrease in morbidity in the vaccinated population, and 38.6 % due to the development of a indirect effect. The predicted avoided costs per 1 vaccinated person is 2,975 thousand rubles. From a societal perspective, the cost-effectiveness of the Rota-V-Aid vaccine will be 364,813 thousand rubles / QALY (quality-adjusted life year), and from a healthcare perspective – 1726,399 thousand rubles / QALY. Thus, in both cases, the cost-effectiveness of RVI vaccination will not exceed the generally accepted threshold of willingness to pay, equal to three times the gross domestic product per capita in the Russian Federation (according to data for 2021 – ~2,7 million rubles). The predicted cost-effectiveness of selective vaccination is significantly lower than that of mass vaccination.   Conclusions. Mass vaccination of children with a 5-valent vaccine against RVI will not only reduce the incidence in the Russian Federation, but, taking into account the assumptions made, can also be considered as a cost-effective intervention.

The burden of rotavirus-associated acute gastroenteritis in the elderly: assessment of the epidemiology in the context of universal childhood vaccination programs

INTRODUCTION

Rotaviruses (RVs) cause acute gastroenteritis (AGE) in infants and young children worldwide and also in older adults (≥60 years), however the burden among this age group is not well understood. Herd immunity through pediatric RV vaccination may reduce the burden of RVGE across all ages, however the impact of pediatric vaccination on burden in older adults is poorly understood.

AREAS COVERED

This systematic review was undertaken to identify studies related to the following objectives: understand the burden of RV in older adults, RV seroprevalence, and the impact of pediatric vaccination on this burden and highlight evidence gaps to guide future research. Of studies identified, 59 studies from two databases were included in this analysis following a review by two reviewers.

EXPERT OPINION

RV is an understudied disease in older adults. We found that 0-62% of patients with AGE tested positive for RV, with results varying by setting, country, and patient age. Results also suggest that pediatric vaccination benefits older adults through herd protection. Several studies showed a reduction in RV incidence after vaccination. However, there was variety in results and lack of consistency in outcomes reported. Further studies targeting older adults are needed to better characterize RV burden.

Epidemiology of norovirus and viral gastroenteritis in Ontario, Canada, 2009-2014

Background

Norovirus is the most common cause of acute gastroenteritis in Canada. The illness causes great morbidity and high societal costs. The objective of this article is to describe the epidemiology of norovirus in the province of Ontario, Canada from 2009 to 2014.

Methods

To assess activity of norovirus and viral gastroenteritis (VGE) in Ontario, three datasets were acquired from the provincial government: two traditional surveillance datasets (outbreak and laboratory) and syndromic surveillance data (telehealth), all spanning 2009-2014. All outbreaks, laboratory submissions and telehealth calls were first assessed for total VGE. Norovirus and norovirus-like illness totals were calculated as a proportion of VGE to estimate agent-specific activity levels. Affected institution types, sexes and age groups were also analyzed.

Results

Between 2009 and 2014, 41.5% of VGE outbreaks, 63.4% of VGE laboratory submissions and 36.6% of all acute gastroenteritis-related (not restricted to viral causes) telehealth calls were attributed to norovirus and norovirus-like illness in Ontario. The most commonly affected institution type was long-term care homes and the most commonly affected age groups were younger (younger than five years) and older (older than 65 years) individuals. Females were slightly more frequently affected than males.

Conclusion

Norovirus and norovirus-like illnesses were the leading cause of VGE in Ontario between 2009 and 2014. They comprised the greatest percentage of VGE when compared with all other VGE-associated viruses. Additional work is needed to determine all component costs and necessary public health actions to reduce the burden of disease.

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.

Global Impact of Rotavirus Vaccination on Diarrhea Hospitalizations and Deaths Among Children <5 Years Old: 2006-2019

BACKGROUND

Since 2006, more than 100 countries have introduced rotavirus vaccine into their immunization programs. We reviewed published data on relative reductions of rotavirus hospitalizations, acute gastroenteritis (AGE) hospitalizations, and AGE deaths among children <5 years old.

METHODS

Articles published from January 1, 2006 to December 31, 2019 with at least 12 months of data before and after rotavirus vaccine introduction were included. Relative reductions were abstracted into a standardized form. Descriptive statistics are presented as medians and interquartile ranges (IQRs).

RESULTS

We reviewed 1827 total records and included 105 articles from 49 countries. Among children <5 years old, there was a median reduction of 59% (IQR, 46-74) in rotavirus hospitalizations, 36% (IQR, 23-47) in AGE hospitalizations, and 36% (IQR, 28-46) AGE mortality. Reductions were larger in countries with low child mortality, among younger age groups, and in countries with higher coverage. The median percentage of specimens that tested positive for rotavirus among children <5 years old hospitalized for diarrhea was 40% (IQR, 28-45) before rotavirus vaccine introduction and 20% (IQR, 20-20) 4 years after introduction.

CONCLUSIONS

Overall, we found sustained impact on rotavirus and AGE hospitalizations and deaths. These results should encourage countries still considering rotavirus vaccine implementation.

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.

A systematic review of factors that influence the acceptability of vaccines among Canadians

BACKGROUND

Canada's National Advisory Committee on Immunization (NACI) provides guidance on the use of vaccines in Canada. To support the expansion of its mandate to include considerations for vaccine acceptability when making recommendations, the NACI Secretariat developed a matrix of factors that influence acceptability. To inform and validate the matrix, we systematically reviewed evidence for factors that influence vaccine acceptability, and for interventions aimed at improving acceptability.

METHODS

On 10-11 October 2018 we searched four bibliographic databases, the Theses Canada Portal, and ClinicalTrials.gov. Two reviewers agreed on the included studies. From each study, we extracted information about the participants, intervention or exposure, comparator, and relevant outcomes. Due to heterogeneity in the reported factors and acceptability indicators we synthesized the findings narratively. We appraised the certainty of evidence using GRADE. For each vaccine-preventable disease we populated a matrix of factors for which there was evidence of an influence on acceptability.

RESULTS

One hundred studies (>1 million participants) contributed data relevant to the public, 16 (6191 participants) to healthcare providers, and three (84 participants) to policymakers. There were 43 intervention studies (~2 million participants). Across vaccines, we identified low certainty evidence for 70 factors relevant to the general population, 56 to high-risk groups, and 30 to healthcare providers. The perceived safety and importance of the vaccine, vaccination history, and receiving a recommendation from a healthcare provider were common influential factors. We found low certainty evidence that reminders for childhood vaccines and policies or delivery models for rotavirus vaccines could improve uptake and coverage. Evidence for other interventions was of very low certainty.

CONCLUSIONS

The NACI vaccine acceptability matrix is useful for categorizing acceptability factors for the general public. Reminder systems may improve the uptake of childhood vaccines. Policies that make the rotavirus vaccine universally available and easily accessible may improve coverage.

FUNDING

This systematic review was completed under contract to the Public Health Agency of Canada, Contract #4600001536.

Impact of Rotavirus Vaccines on Gastroenteritis Hospitalizations in Western Australia: A Time-series Analysis

Background

Rotavirus vaccination was introduced into the Australian National Immunisation Program in mid-2007. We aimed to assess the impact of the rotavirus vaccination program on the burden of hospitalizations associated with all-cause acute gastroenteritis (including rotavirus gastroenteritis and non-rotavirus gastroenteritis) in the Aboriginal and non-Aboriginal population in Western Australia.

Methods

We identified all hospital records, between July 2004 and June 2012, with a discharge diagnosis code for all-cause gastroenteritis. Age-specific hospitalization rates for rotavirus and non-rotavirus acute gastroenteritis before and after the introduction of the rotavirus vaccination program were compared. Interrupted time-series models were used to examine differences in the annual trends of all-cause gastroenteritis hospitalization between the two periods.

Results

Between July 2004 and June 2012, there were a total of 106,974 all-cause gastroenteritis-coded hospitalizations (1,381 rotavirus-coded [15% among Aboriginal] and 105,593 non-rotavirus gastroenteritis-coded [7% among Aboriginal]). Following rotavirus vaccination introduction, significant reductions in rotavirus-coded hospitalization rates were observed in all children aged <5 years (up to 79% among non-Aboriginal and up to 66% among Aboriginal). Among adults aged ≥65 years, rotavirus-coded hospitalizations were 89% (95% confidence interval, 16–187%) higher in the rotavirus vaccination program period. The time-series analysis suggested reductions in all-cause gastroenteritis hospitalizations in the post-vaccination period among both vaccinated and unvaccinated (age-ineligible) children, with increases observed in adults aged ≥45 years.

Conclusions

Rotavirus vaccination has been associated with a significant decline in gastroenteritis hospitalizations among children. The increase in the elderly requires further evaluation, including assessment of the cost-benefits of rotavirus vaccination in this population.

Gap analyses to assess Canadian readiness for respiratory syncytial virus vaccines: Report from an expert retreat

Respiratory syncytial virus (RSV) can cause severe disease in infants and older adults. Various vaccine candidates are in development and may become authorized for use in Canada within the next 2-5 years. The Public Health Agency of Canada sought to enhance preparedness for RSV vaccine and passive immunization candidates by organizing an expert retreat to identify knowledge gaps in surveillance and research and development in the context of provincial and territorial RSV public health priorities. We determined that RSV candidate vaccines in development directly address four out of five identified public health priorities, and identified remaining data gaps around vaccine efficacy and effectiveness. We determined that limited or sufficient surveillance data is available to support decision-making for four out of five RSV public health priorities and identified data gaps for several key populations: (i) for RSV cases under 17 years of age, gaps remain for denominator data to calculate incidence and data on medically attended outpatient visits; (ii) for RSV cases in Indigenous and remote communities, gaps remain for data on incidence, prevalence, specific risk factors, feasibility and acceptability; and (iii) for RSV cases in older adults, gaps remain for data on incidence. This process demonstrated the feasibility of, and stakeholder support for, gap analyses in surveillance data to support decisions about prospective vaccines and immune products.

Measurement of coverage, compliance and determinants of uptake in a publicly funded rotavirus vaccination programme: a retrospective cohort study

OBJECTIVES

In June 2015, Alberta, Canada instituted a universal publicly funded rotavirus vaccination programme (Rotarix, RV1), with vaccine doses scheduled for 2 and 4 months of age. Vaccination was restricted so that infants were only allowed to receive first dose between 6 and 20 weeks of age, and second dose before eight calendar months of age. We assessed the coverage and schedule non-compliance of rotavirus vaccination for babies born between June 2015 and August 2016, that is, since the inception of the publicly funded rotavirus vaccination programme, and determined factors associated with rotavirus vaccine uptake.

DESIGN

Retrospective cohort study using linked administrative health data.

SETTING

Alberta, Canada.

PARTICIPANTS

Cohort of 66 689 children. PRIMARY AND SECONDARY OUTCOME MEASURES: (1) First and second dose rotavirus vaccination coverage, (2) percent of children non-compliant with recommended vaccine schedule and (3) adjusted ORs for factors associated with vaccination status.

RESULTS

For the 66 689 children included in the study, coverage levels for one-dose and two-dose rotavirus vaccination were 87% and 83%, respectively. In comparison, two-dose diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b vaccine coverage was 92%, despite having the same dosing schedule. Schedule non-compliance during the publicly funded programme was very low. We observed socioeconomic disparities in the uptake of the vaccine, with income, location of residence and number of children in the household all contributing to the odds of a child being vaccinated with rotavirus.

CONCLUSIONS

Compliance to the recommended rotavirus schedule was very high, suggesting that even with the restrictive rotavirus vaccine schedule, the vaccine can be delivered on-time. However, rotavirus vaccine coverage remained lower than DTaP, a similarly scheduled childhood vaccination. We also observed socioeconomic disparities in vaccine uptake. These findings raise concerns about rotavirus protection in the groups at highest risk for gastrointestinal illness, including low-income and rural populations.

Equity and impact: Ontario's infant rotavirus immunization program five years following implementation. A population-based cohort study

BACKGROUND

Ontario implemented a publicly-funded rotavirus (RV) immunization program in 2011. Our objectives were to evaluate its impact on hospitalizations and emergency department (ED) visits for acute gastroenteritis (AGE) five years after implementation.

METHODS

We performed a population-based longitudinal retrospective cohort study to identify hospitalizations and ED visits for RV-AGE and overall AGE in all age groups using ICD-10 codes between August 1, 2005 and March 31, 2016. A negative binomial regression model that included the effect of time was used to calculate rates, rate ratios (RRs) and 95% confidence intervals (CIs) for AGE before and after the program's implementation, after adjusting for age, seasonality and secular trends. We examined the seasonality of RV-AGE hospitalizations among children under five before and after the program and explored its equity impact.

RESULTS

Following program implementation, RV-AGE hospitalizations and ED visits among children under five years declined by 76% (RR 0.24, 95% CI 0.20-0.28) and 68% (RR 0.32, 95% CI 0.21-0.50), respectively. In addition, hospitalizations and ED visits for overall AGE declined by 38% (RR 0.62, 95% CI 0.59-0.65) and 26% (RR 0.74, 95% CI 0.73-0.76), respectively, among children under age five. Significant reductions in both outcomes were also found across a range of age-strata. In the pre-program period, the mean monthly hospitalization rate for RV-AGE among children residing in the most marginalized neighbourhoods was 33% higher than those residing in the least marginalized (RR 1.33, 95% CI 1.17-1.52), this disparity was not evident in the program period (RR 0.95, 95% CI 0.69-1.32). We found no evidence of a seasonal shift in rotavirus pediatric hospitalizations.

INTERPRETATION

The introduction of routine infant rotavirus immunization has had a substantial population impact in Ontario. Our study confirms herd effects and suggests the program may have reduced previous inequities in the burden of pediatric rotavirus hospitalizations.

Evaluation of the Impact of a Rotavirus Vaccine Program on Pediatric Acute Gastroenteritis Hospitalizations: Estimating the Overall Effect Attributable to the Program as a Whole and as a Per-Unit Change in Rotavirus Vaccine Coverage

Estimation of the overall effect of a vaccine program is essential, but the effect is typically estimated for a whole program. We estimated the overall effect of the Quebec rotavirus vaccine program, launched in November 2011, and the effect for each 10% increase in rotavirus vaccine coverage on pediatric hospitalizations for all-cause acute gastroenteritis. We implemented negative binomial regressions adjusted for seasonality, long-term trends, and infection dynamics, to estimate the effect of the vaccine program as: 1) a dichotomous variable, representing program presence/absence, and linear term to account for changes in trend in the period after the program began; and 2) a continuous variable, representing rotavirus vaccine coverage. Using exposure 1, the vaccine program was associated with a 51.2% (95% confidence interval (CI): 28.5, 66.7) relative decline in adjusted weekly hospitalization rates for all-cause acute gastroenteritis as of December 28, 2014. Using exposure 2, a 10% increase in rotavirus ≥1-dose coverage was associated with a 7.1% (95% CI: 3.5, 10.5) relative decline in adjusted weekly rates, with maximum coverage of 87.0% associated with a 47.2% (95% CI: 26.9, 61.9) relative decline. Estimation of the overall effect attributable to a change in vaccine coverage might be a useful addition to standard measurement of the overall effect.

Rotavirus Gastroenteritis Infection Among Children Vaccinated and Unvaccinated With Rotavirus Vaccine in Southern China: A Population-Based Assessment

IMPORTANCE

Since 2000, the Lanzhou lamb rotavirus vaccine has been exclusively licensed in China for voluntary rotavirus gastroenteritis (RV-GE) prevention.

OBJECTIVE

To evaluate the association of the Lanzhou lamb rotavirus vaccination with RV-GE among children in southern China.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional, ecological study was set in Guangzhou, China. Participants were infants possibly vaccinated (aged 2 months to 3 years) and the children ineligible for vaccination (aged ≥4 years). The study was conducted from May 1, 2007, to April 30, 2016, and the data analysis was conducted in July 2016.

MAIN OUTCOMES AND MEASURES

Annual median age at onset of RV-GE and seasonal distribution of incidence. Cases of RV-GE in Guangzhou, China, diagnosed from May 1, 2007, to April 30, 2016, and reported to the National Information System for Disease Control and Prevention were examined. Poisson regression models were fitted among 32 452 children younger than 4 years and among 450 children who had been ineligible for vaccination, while controlling for secular trends, socioeconomic status, and meteorological factors. Logistic regression was used to assess the indirect effects provided by the vaccinated infants from 2009 to 2011 on unvaccinated infants aged 2 to 35 months based on a separate case-control data set.

RESULTS

During 9 seasons, 119 705 patients with gastroenteritis were reported; 33 407 were confirmed for RV-GE (21 202 [63.5%] male, 32 022 [95.8%] aged <4 years, and 31 306 [93.8%] residing in urban districts). The median age at onset for all patients with RV-GE increased from 11 months during the 2007 season to 15 months during the 2015 season, and the onset, peak, and cessation of incidence were delayed. When citywide vaccination coverage in the prior 12 months was classified into high and low groups (≥8.36% vs <8.36%), the incidence rate ratio for the high coverage group decreased by 32.4% among children younger than 4 years (incidence rate ratio, 0.676; 95% CI, 0.659-0.693; P < .001). Among the children ineligible for vaccination, the incidence rate ratio in higher coverage periods was 0.790 (95% CI, 0.351-0.915; P < .001) compared with the lower coverage. Compared with districts with 14% or less vaccination coverage, the adjusted odds ratio for RV-GE among unvaccinated children younger than 3 years was 0.85 (95% CI, 0.73-0.99; P = .03) for districts with 15% to 19% of coverage, and 0.79 (95% CI, 0.67-0.93; P = .004) for districts with more than 20% of coverage.

CONCLUSIONS AND RELEVANCE

This study provides evidence of the population health benefits of the Lanzhou lamb rotavirus vaccination in preventing RV-GE among children in China younger than 4 years, including herd effects.

A comparison of the Allplex™ bacterial and viral assays to conventional methods for detection of gastroenteritis agents

Objective

Molecular methods to detect diarrheal pathogens are increasingly being used in place of conventional methods. We compared a new multiplex real-time PCR assay for detection of both bacterial and viral gastroenteritis agents, the Allplex™ Gastrointestinal Panel Assays (AGPA), to conventional methods (stool culture for bacterial pathogens and electron microscopy (EM) for viral pathogens).

Results

Gastrointestinal viruses, in particular norovirus genogroup II viruses, were detected by the AGPA in a high number of specimens that were negative by EM. For bacterial pathogens, the AGPA was able to detect the organisms grown in culture with high sensitivity and additionally detected several types of E. coli, such as enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), and non-O157 Shiga toxin-producing E. coli (STEC), that could not be detected with conventional culture methods. Overall, the AGPA had a > 2-fold higher detection rate than the conventional methods, with 24/135 (17.8%) samples positive by conventional methods and 60/135 (44.4%) by AGPA. Thus, diarrhea pathogen detection rates increased substantially with the use of the AGPA as compared to conventional methods.

Indirect Rotavirus Vaccine Effectiveness for the Prevention of Rotavirus Hospitalization: A Systematic Review and Meta-Analysis

Two rotavirus vaccines, RotaTeq and Rotarix, are licensed for global use; however, the protection they confer to unvaccinated individuals through indirect effects remains unknown. We systematically reviewed the literature and quantified indirect rotavirus vaccine effectiveness (VE) for preventing rotavirus hospitalization in children aged less than 5 years. From 148 identified abstracts, 14 studies met our eligibility criteria. In our main analysis using a random-effects model, indirect rotavirus VE was 48% (95% confidence interval [CI]: 39-55%). In a subgroup analysis by country income level, indirect VE was greater in high-income countries (52%; 95% CI: 43-60%) than in low- and middle-income countries (LMICs) (25%; 95% CI: 5-41%). In a sensitivity analysis using a quality-effects model, the indirect VE in LMICs was not statistically significant (25%; 95% CI: 0-44%). Our findings highlight the importance of increasing rotavirus vaccine coverage, particularly in LMICs where evidence for indirect VE is limited and rotavirus burden is high.

Rotavirus genotypes circulating in Ontario, Canada, before and after implementation of the rotavirus immunization program

BACKGROUND AND OBJECTIVES

Ontario introduced a universal publicly-funded group A rotavirus (RVA) immunization program in August 2011, using monovalent vaccine. RVA immunization programs have decreased the incidence of RVA acute gastroenteritis in many countries but it is unclear if it will contribute to the emergence of certain genotypes. We monitored RVA trends and genotypes in Ontario before and after implementation of the publicly-funded immunization program.

METHODS

RVA detection was conducted at Public Health Ontario Laboratories from January 2009 to December 2011 (pre-program period) and January 2012 to October 2015 (publicly-funded RVA immunization program period) and number of RVA-positive specimens and percent positivity were analysed. A convenience sample of RVA-positive stool specimens, from September 2010 to December 2011 (pre-program period) and January 2012 to June 2013 (program period), were genotyped using heminested PCR. A literature review on the burden of illness from emergent genotype was performed.

RESULTS

Stool specimens showed a significant decrease in RVA percent positivity from the 36 month pre-program period (14.4%; 1537/10700) to the 46 month program period (6.1%; 548/9019). An increase in the proportion of RVA G10 among genotyped specimens, associated with five different P genotypes, from the pre-program (6.3%; 13/205) to the program (31.5%; 40/127) period was observed. Our literature review identified approximately 200 G10-positive human stool specimens from 16 different countries.

CONCLUSIONS

This study documented a decrease in the number of RVA-positive specimens and percent positivity after implementation of the immunization program. An unexpected increase in the proportion of RVA G10 was detected following program introduction. Ongoing RVA surveillance is important in evaluating both the long-term impact of immunization and emergence of RVA genotypes.

Rotavirus vaccine coverage and factors associated with uptake using linked data: Ontario, Canada

BACKGROUND

In August 2011, Ontario, Canada introduced a rotavirus immunization program using Rotarix™ vaccine. No assessments of rotavirus vaccine coverage have been previously conducted in Ontario.

METHODS

We assessed vaccine coverage (series initiation and completion) and factors associated with uptake using the Electronic Medical Record Administrative data Linked Database (EMRALD), a collection of family physician electronic medical records (EMR) linked to health administrative data. Series initiation (1 dose) and series completion (2 doses) before and after the program's introduction were calculated. To identify factors associated with series initiation and completion, adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) were calculated using logistic regression.

RESULTS

A total of 12,525 children were included. Series completion increased each year of the program (73%, 79% and 84%, respectively). Factors associated with series initiation included high continuity of care (aOR = 2.15; 95%CI, 1.61-2.87), maternal influenza vaccination (aOR = 1.55; 95%CI,1.24-1.93), maternal immmigration to Canada in the last five years (aOR = 1.47; 95% CI, 1.05-2.04), and having no siblings (aOR = 1.62; 95%CI,1.30-2.03). Relative to the first program year, infants were more likely to initiate the series in the second year (aOR = 1.71; 95% CI 1.39-2.10) and third year (aOR = 2.02; 95% CI 1.56-2.61) of the program. Infants receiving care from physicians with large practices were less likely to initiate the series (aOR 0.91; 95%CI, 0.88-0.94, per 100 patients rostered) and less likely to complete the series (aOR 0.94; 95%CI, 0.91-0.97, per 100 patients rostered). Additional associations were identified for series completion.

CONCLUSIONS

Family physician delivery achieved moderately high coverage in the program's first three years. This assessment demonstrates the usefulness of EMR data for evaluating vaccine coverage. Important insights into factors associated with initiation or completion (i.e. high continuity of care, smaller roster sizes, rural practice location) suggest areas for research and potential program supports.

The Incidence of Acute Gastrointestinal Illness in Canada, Foodbook Survey 2014-2015

Acute gastrointestinal illness (AGI) is an important public health issue, with many pathogen sources and modes of transmission. A one-year telephone survey was conducted in Canada (2014-2015) to estimate the incidence of self-reported AGI in the previous 28 days and to describe health care seeking behaviour, using a symptom-based case definition. Excluding cases with respiratory symptoms, it is estimated that there are 0.57 self-reported AGI episodes per person-year, almost 19.5 million episodes in Canada each year. The proportion of cases seeking medical care was nearly 9%, of which 17% reported being requested to submit a sample for laboratory testing, and 49% of those requested complied and provided a sample. Results can be used to inform burden of illness and source attribution studies and indicate that AGI continues to be an important public health issue in Canada.

Recommendations for the use of rotavirus vaccines in infants

The present statement provides information concerning the clinical rotavirus disease and rotavirus vaccines in Canada. Since the implementation of publically funded rotavirus vaccine programs in Canada, increasing evidence has been accumulating globally as to the effectiveness of rotavirus vaccines in the prevention of acute gastroenteritis. Current data estimate vaccine effectiveness to be in the order of 85% for preventing severe disease, including hospitalizations and emergency department visits, when vaccine coverage is high. Also, substantial herd protection in older children has been documented. Post-marketing surveillance has detected a very small increased risk of intussusception (one to three per 100,000) in children, usually occurring within 1 week of vaccination. Infants who have an identified significant immune deficiency or are suspected of having such a condition should not receive rotavirus vaccine.

Assessing the risk of intussusception and rotavirus vaccine safety in Canada

BACKGROUND

Intussusception has been identified as a rare adverse event following rotavirus immunization. We sought to determine the incidence of intussusception among infants in Canada both before and after introduction of rotavirus immunization programs.

METHODS

We used Canadian Institute for Health Information (CIHI) Discharge Abstract Database (DAD) to identify infants under 1 y of age who were admitted to a Canadian hospital, which the exception of Quebec, which does not submit data to CIHI, with a diagnosis of intussusception (ICD-10 code K56.1, and ICD-9 code 560) between January 1st, 2003 and December 31, 2013. We compared rates of intussusception hospitalization before and after rotavirus vaccine program introduction. Rates were adjusted for calendar year, age (in months), sex and region using Poisson regression models. Denominator data for infants under 1 year, stratified by age in months, were obtained from Statistics Canada.

RESULTS

Annual intussusception hospitalization rates ranged from 20-30 per 100,000 infants over the study period, with no evidence of a trend over time. Intussusception hospitalization rates were highest in infants 4 to <8 months and lowest in those under 2 months or between 10 and <12 months. Males had higher rates than females both overall and within each age group. The rate of intussusception hospitalization after rotavirus vaccine program introduction was 22.4 (95% CI: 18.3, 27.4) compared to 23.4 (95% CI: 21.5, 25.4) per 100,000 before program introduction.

CONCLUSIONS

We have described baseline intussusception hospitalization rates for infants in Canada and have found no evidence of a change in rate after implementation of routine rotavirus immunization programs.

Incidence of rotavirus gastroenteritis hospitalizations and genotypes, before and five years after introducing universal immunization in Israel

BACKGROUND

Uncertainty exists about the sustainability of the reduction in rotavirus gastroenteritis (RVGE) following the introduction of rotavirus vaccines into national immunization programs, and on its potential impact on circulating genotypes. RotaTeq was introduced into the Israeli national immunization program in December 2010, and vaccination coverage is around 80%.

AIMS

To examine the change in incidence of RVGE hospitalization and rotavirus genotypes, during the five years after introduction of RotaTeq into the Israeli national immunization program.

METHODS

Data were obtained prospectively on hospitalization of children aged 0-59months due to acute gastroenteritis (N=7346) from three hospitals in northern Israel. Stool samples were tested for rotavirus by immunochromatography. Rotavirus was genotyped (N=506) by RT-PCR and/or sequencing.

RESULTS

The average incidence of RVGE hospitalization declined by 61.0% (95% CI 49.0-73.4%), from 5.6 per 1000 (95% CI 5.0-6.2) in the pre-universal immunization period (2008-2010) to 2.2 per 1000 (95% CI 1.8-2.5) during the universal immunization period (2012-2015), but yearly fluctuations were still observed. The most common genotypes in the pre-universal immunization period were G1P[8] (35.3%) followed by G2P[4] (15.5%), G3P[8] (8.8%), G4P[8] (4.3%) and G9P[8] (4.3%), and 19.5% were mixed infections. The dominance of G1P[8] continued into the universal immunization period (48.6%), followed by G3P[8] (21.5%), G9P[8] (15.9%) and G12P[8] (4.7%), while mixed rotavirus infections were no longer detected.

CONCLUSIONS

Universal immunization with RotaTeq in Israel was associated a sustained reduction in RVGE hospitalization. It is unclear whether changes in the circulating rotavirus genotypes are due to vaccine-induced selective pressure. Assessment of the long-term impact of rotavirus vaccination on the incidence of rotavirus gastroenteritis and continued strain surveillance is warranted.

Rotavirus vaccines: current global impact and future perspectives

As of May 2016, 81 countries have introduced Rotarix or RotaTeq rotavirus vaccines into their national immunization program. Despite initially slow uptake in some countries and differences in vaccine effectiveness (VE) between high-, low- and middle-income countries, impact of the vaccines has been swift and striking in all settings, with good VE against vaccine-type and nonvaccine-type strains. Newly published research indicates poor nutrition is associated with decreased VE and breastfeeding at the time of vaccination does not affect vaccine response. Vaccines in development and proposed alternate schedules also promise to address limitations of the current vaccines and optimize rotavirus disease prevention.