Impact of rotavirus vaccination on childhood gastroenteritis-related mortality and hospital discharges in Panama

Norovirus in children under 2 years of age: an epidemiological study in Panama during the COVID-19 pandemic

Introduction

Norovirus infection is a common cause of acute gastroenteritis (AGE). Surveillance activities are important to aid investigation into effective norovirus control strategies, including vaccination. Here, we report ancillary findings related to the incidence, prevalence, and etiology of AGE caused by norovirus in Panama after adjustment of study methodology to comply with national coronavirus disease 2019 (COVID-19) mandates.

Methods

In January 2020, children aged <2 years began enrolling into an epidemiological study in Panama to estimate the burden of norovirus in preparation for evaluating upcoming prevention strategies. This included an observational, longitudinal, community-based AGE surveillance study and a hospital-based AGE surveillance study. For the longitudinal study, healthy children aged 5-18 months were enrolled from January 6 through March 23, 2020, with a follow-up of approximately 6 months. The last participant was contacted on September 23, 2020. For the hospital-based study, starting on January 21, 2020, children aged <2 years who were admitted to the Hospital del Niño Dr. José Renán Esquivel in Panama City due to AGE were evaluated. The last sample was collected on September 29, 2020. Collected stool samples were tested for norovirus as well as astrovirus, sapovirus, and various enteropathogens. Unfortunately, this study was disrupted by the subsequent implementation of disease transmission control procedures for the COVID-19 pandemic, and the study methodology was revised to comply with COVID-19 mandates.

Results

In the longitudinal surveillance cohort [N = 400 (Chiriquí, n = 239; Panama, n = 161)], a total of 185 AGE episodes were documented (Chiriquí, n = 85; Panama, n = 100) resulting in an overall AGE incidence of 11.6 (95% CI: 9.99-13.4) episodes per 100 child-months. The norovirus-related AGE incidence was 0.3 (95% CI: 0.10-0.73) episodes per 100 child-months (5/185 AGE episodes) and the prevalence of norovirus was 4.6% (13/282 stool samples collected). In the hospital-based surveillance cohort, at least one pathogen was detected in 50% of samples (44/88 stool samples collected) and norovirus prevalence was 6.8% (6/88 stool samples collected).

Discussion

This report demonstrates how the occurrence of the COVID-19 pandemic hindered the conduct of clinical trials. However, this also created unique research opportunities to investigate the potential impact of pandemic control measures on the etiology of infectious diarrheal disease.

Rotavirus in developing countries: molecular diversity, epidemiological insights, and strategies for effective vaccination

Rotavirus (RV) causes the loss of numerous children's lives worldwide each year, and this burden is particularly heavy in low- and lower-middle-income countries where access to healthcare is limited. RV epidemiology exhibits a diverse range of genotypes, which can vary in prevalence and impact across different regions. The human genotypes that are most commonly recognized are G1P[8], G2P[4], G3P[8], G4P[8], G8P[8], G9P[8], and G12P[8]. The diversity of rotavirus genotypes presents a challenge in understanding its global distribution and developing effective vaccines. Oral, live-attenuated rotavirus vaccines have undergone evaluation in various contexts, encompassing both low-income and high-income populations, demonstrating their safety and effectiveness. Rotavirus vaccines have been introduced and implemented in over 120 countries, offering an opportunity to assess their effectiveness in diverse settings. However, these vaccines were less effective in areas with more rotavirus-related deaths and lower economic status compared to wealthier regions with fewer rotavirus-related deaths. Despite their lower efficacy, rotavirus vaccines significantly decrease the occurrence of diarrheal diseases and related mortality. They also prove to be cost-effective in regions with a high burden of such diseases. Regularly evaluating the impact, influence, and cost-effectiveness of rotavirus vaccines, especially the newly approved ones for worldwide use, is essential for deciding if these vaccines should be introduced in countries. This is especially important in places with limited resources to determine if a switch to a different vaccine is necessary. Future research in rotavirus epidemiology should focus on a comprehensive understanding of genotype diversity and its implications for vaccine effectiveness. It is crucial to monitor shifts in genotype prevalence and their association with disease severity, especially in high-risk populations. Policymakers should invest in robust surveillance systems to monitor rotavirus genotypes. This data can guide vaccine development and public health interventions. International collaboration and data sharing are vital to understand genotype diversity on a global scale and facilitate the development of more effective vaccines.

Rotavirus Vaccine Impact since Its Introduction in the National Immunization Program of Argentina

INTRODUCTION

Rotavirus (RV) is the most common cause of childhood diarrhea. Argentina introduced RV vaccination in the National Immunization Program in January 2015. This study evaluates the impact of RV vaccine implementation on the burden of acute diarrheal disease (ADD) and RV positive cases, and hospitalizations among children in Argentina.

METHODS

A counterfactual time-series analysis was performed. Data on ADD (2013-2018) and RV diarrhea (2012-2018) cases in children aged < 5 years were collected from the National Healthcare Surveillance System (clinical and laboratory data). Data on hospital discharges following ADD and RV diarrhea (2011-2017) were retrieved from the Health Statistics and Information Office. All data were classified by the age groups < 1 year, < 2 years, 2-5 years. Vaccine impact was defined as the difference between the predicted time trend (simulated using 2012-2014 data) and the actual post-vaccination data (2015-2018).

RESULTS

A significant reduction of 22.1% of notified ADD cases and 15.4% of hospital discharges following ADD among children < 2 years was observed in the 3 years after RV vaccine implementation. Data also showed a significant decline of 54.0% and 59.4% of notified RV cases in children < 2 and < 1 years, respectively, and a reduction of 39.3% and 40.8% in RV hospital discharges for the same age groups.

CONCLUSION

This study shows a significant reduction in notified ADD cases and RV cases and hospital discharges following ADD and RV cases in children < 2 years after RV vaccine introduction in Argentina in 2015.

Suppression of classical nuclear import pathway by importazole and ivermectin inhibits rotavirus replication

BACKGROUND

Rotavirus is the foremost cause of acute gastroenteritis among infants in resource-poor countries, causing severe morbidity and mortality. The currently available rotavirus vaccines are effective in reducing severity of the disease but not the infection rates, thus antivirals as an adjunct therapy are needed to reduce the morbidity in children. Viruses rely on host cellular machinery for nearly every step of the replication cycle. Therefore, targeting host factors that are indispensable for virus replication could be a promising strategy.

OBJECTIVES

To assess the therapeutic potential of ivermectin and importazole against rotaviruses.

METHODS

Antirotaviral activity of importazole and ivermectin was measured against various rotavirus strains (RV-SA11, RV-Wa, RV-A5-13, RV-EW) in vitro and in vivo by quantifying viral protein expression by western blot, analysing viroplasm formation by confocal microscopy, and measuring virus yield by plaque assay.

RESULTS

Importin-β1 and Ran were found to be induced during rotavirus infection. Knocking down importin-β1 severely impaired rotavirus replication, suggesting a critical role for importin-β1 in the rotavirus life cycle. In vitro studies revealed that treatment of ivermectin and importazole resulted in reduced synthesis of viral proteins, diminished production of infectious virus particles, and decrease in viroplasm-positive cells. Mechanistic study proved that both drugs perform antirotavirus activity by inhibiting the function of importin-β1. In vivo investigations in mice also confirmed the antirotavirus potential of importazole and ivermectin at non-toxic doses. Treatments of rotavirus-infected mice with either drug resulted in diminished shedding of viral particles in the stool sample, reduced expression of viral protein in the small intestine and restoration of damaged intestinal villi comapared to untreated infected mice.

CONCLUSIONS

The study highlights the potential of importazole and ivermectin as antirotavirus therapeutics.

Quercetin, a flavonoid, combats rotavirus infection by deactivating rotavirus-induced pro-survival NF-κB pathway

Rotavirus (RV) is the leading cause of acute gastroenteritis and watery diarrhea in children under 5 years accounting for high morbidity and mortality in countries with poor socioeconomic status. Although vaccination against RV has been implemented in more than 100 countries, the efficacy of vaccine has been challenged in low-income settings. The lack of any FDA-approved drug against RV is an additional concern regarding the treatment associated with rotavirus-induced infantile death. With the purpose for the discovery of anti-RV therapeutics, we assessed anti-rotaviral potential of quercetin, a well-characterized antioxidant flavonoid. In vitro study revealed that quercetin treatment resulted in diminished production of RV-SA11 (simian strain) viral particles in a concentration-dependent manner as estimated by the plaque assay. Consistent with this result, Western blot analysis also revealed reduced synthesis of viral protein in quercetin-treated RV-SA11-infected MA104 cells compared to vehicle (DMSO) treated controls. Not surprisingly, infection of other RV strains A5-13 (bovine strain) and Wa (Human strain) was also found to be abridged in the presence of quercetin compared to DMSO. The IC₅₀ of quercetin against three RV strains ranges between 2.79 and 4.36 Mm, and S.I. index is greater than 45. Concurrent to the in vitro results, in vivo study in mice model also demonstrated reduced expression of viral proteins and viral titer in the small intestine of quercetin-treated infected mice compared to vehicle-treated infected mice. Furthermore, the result suggested anti-rotaviral activity of quercetin to be interferon-independent. Mechanistic study revealed that the antiviral action of quercetin is co-related with the inhibition of RV-induced early activation of NF-κB pathway. Overall, this study delineates the strong anti-RV potential of quercetin and also proposes it as future therapeutics against rotaviral diarrhea.

Prevalence and characteristics of rotavirus acute gastroenteritis among under-five children in ahmadu bello university teaching hospital, Zaria, Nigeria

Background:

Rotavirus infection is a significant cause of gastroenteritis in developing countries and, in severe cases even leads to death. The impact of rotavirus vaccine introduction in reducing the rotavirus disease burden in children was well known. The study was aimed to determine the prevalence and clinical characteristics of rotavirus gastroenteritis before the introduction of rotavirus vaccine into Nigeria's routine immunization program.

Materials and Methods:

We conducted a cross-sectional hospital-based study involving 735 children aged 0–59 months with acute gastroenteritis hospitalized at the Ahmadu Bello University Teaching Hospital Zaria from September 2017 to August 2020. Relevant sociodemographic and clinical data were obtained and entered into the World Health Organization standardized case investigation forms. Stool specimens were tested for rotavirus Group A antigen using the ProSpecT™ Rotavirus Microplate Assay by Thermoscientific Oxoid Microbiology UK.

Results:

One hundred and fifty-three stool samples tested positive for rotavirus giving a prevalence of 20.8%. One hundred and two (66.7%) children with rotavirus gastroenteritis were infants. There were 87 males and 66 females with M: F ratio of 1.3:1. Only 30 (19.6%) children with rotavirus-associated diarrhea presented with severe dehydration. The presence of vomiting was significantly associated with rotavirus diarrhea (P = 0.001). More cases of rotavirus diarrhea occurred in September through February. None of the studied children were vaccinated against rotavirus.

Conclusion:

The prevalence of rotavirus diarrhea remains high in this study. Infants were recognized as a high-risk group, and none of them were vaccinated against rotavirus and this underscores the urgent need for implementing the rotavirus vaccine in the national vaccination program to reduce the disease burden in the country.

Emergence of equine-like G3 strains as the dominant rotavirus among children under five with diarrhea in Sabah, Malaysia during 2018-2019

Rotavirus infection is a dilemma for developing countries, including Malaysia. Although commercial rotavirus vaccines are available, these are not included in Malaysia's national immunization program. A scarcity of data about rotavirus genotype distribution could be partially to blame for this policy decision, because there are no data for rotavirus genotype distribution in Malaysia over the past 20 years. From January 2018 to March 2019, we conducted a study to elucidate the rotavirus burden and genotype distribution in the Kota Kinabalu and Kunak districts of the state of Sabah. Stool specimens were collected from children under 5 years of age, and rotavirus antigen in these samples was detected using commercially available kit. Electropherotypes were determined by polyacrylamide gel electrophoresis of genomic RNA. G and P genotypes were determined by RT-PCR using type specific primers. The nucleotide sequence of the amplicons was determined by Sanger sequencing and phylogenetic analysis was performed by neighbor-joining method. Rotavirus was identified in 43 (15.1%) children with watery diarrhea. The male:female ratio (1.9:1) of the rotavirus-infected children clearly showed that it affected predominantly boys, and children 12-23 months of age. The genotypes identified were G3P[8] (74% n = 31), followed by G1P[8] (14% n = 6), G12P[6](7% n = 3), G8P[8](3% n = 1), and GxP[8] (3% n = 1). The predominant rotavirus circulating among the children was the equine-like G3P[8] (59.5% n = 25) with a short electropherotype. Eleven electropherotypes were identified among 34 strains, indicating substantial diversity among the circulating strains. The circulating genotypes were also phylogenetically diverse and related to strains from several different countries. The antigenic epitopes present on VP7 and VP4 of Sabahan G3 and equine-like G3 differed considerably from that of the RotaTeq vaccine strain. Our results also indicate that considerable genetic exchange is occurring in Sabahan strains. Sabah is home to a number of different ethnic groups, some of which culturally are in close contact with animals, which might contribute to the evolution of diverse rotavirus strains. Sabah is also a popular tourist destination, and a large number of tourists from different countries possibly contributes to the diversity of circulating rotavirus genotypes. Considering all these factors which are contributing rotavirus genotype diversity, continuous surveillance of rotavirus strains is of utmost importance to monitor the pre- and post-vaccination efficacy of rotavirus vaccines in Sabah.

15-year experience with rotavirus vaccination in Mexico: a systematic literature review

A systematic review was conducted in Mexico to consolidate and evaluate evidence after 15 years of rotavirus vaccination, according to the National Immunization Program. Five databases were screened to identify published articles (January 2000-February 2020) with evidence on all clinical and epidemiological endpoints (e.g. immunogenicity, safety, efficacy, impact/effectiveness) of rotavirus vaccination in Mexico. Twenty-two articles were identified (observational studies including health-economic models: 17; randomized controlled trials: 5). Fourteen studies evaluated a human attenuated vaccine (HRV), four studies evaluated both vaccines, and only two evaluated a bovine-human reassortant vaccine, with local efficacy data only for HRV. Local evidence shows vaccines are safe, immunogenic, efficacious, and provide an acceptable risk-benefit profile. The benefits of both vaccines in alleviating the burden of all-cause diarrhea mortality and morbidity are documented in several local post-licensure studies. Findings signify overall benefits of rotavirus vaccination and support the continued use of rotavirus vaccine in Mexico.

Fifteen years of experience with the oral live-attenuated human rotavirus vaccine: reflections on lessons learned

INTRODUCTION

Rotavirus (RV) disease remains a prominent cause of disease burden in children <5 years of age worldwide. However, implementation of RV vaccination has led to significant reductions in RV mortality, compared to the pre-vaccination era. This review presents 15 years of real-world experience with the oral live-attenuated human RV vaccine (HRV; Rotarix). HRV is currently introduced in ≥80 national immunization programs (NIPs), as 2 doses starting from 6 weeks of age.

AREAS COVERED

The clinical development of HRV and post-marketing experience indicating the impact of HRV vaccination on RV disease was reviewed.

EXPERT OPINION

In clinical trials, HRV displayed an acceptable safety profile and efficacy against RV-gastroenteritis, providing broad protection against heterotypic RV strains by reducing the consequences of severe RV disease in infants. Real-world evidence shows substantial, rapid reduction in the number of RV infections and associated hospitalizations following introduction of HRV in NIPs, regardless of economic setting. Indirect effects against RV disease are also observed, such as herd protection, decrease in nosocomial infections incidence, and a reduction of disease-related societal/healthcare costs. However, not all countries have implemented RV vaccination. Coverage remains suboptimal and should be improved to maximize the benefits of RV vaccination.

Global impact of rotavirus vaccine introduction on rotavirus hospitalisations among children under 5 years of age, 2008-16: findings from the Global Rotavirus Surveillance Network

Summary

Background

Rotavirus vaccine use in national immunisation programmes has led to declines in hospital admissions for rotavirus gastroenteritis among children; however, the global impact of rotavirus vaccine introduction has not been described using primary data. We describe the impact of rotavirus vaccine introduction on admissions for acute rotavirus gastroenteritis in primarily low-income and middle-income countries, using 9 years of data from the WHO-coordinated Global Rotavirus Surveillance Network (GRSN).

Methods

Between Jan 1, 2008, and Dec 31, 2016, children younger than 5 years of age who were admitted to hospital with acute gastroenteritis were prospectively enrolled in GRSN sites. We included sites that enrolled children and collected stool specimens monthly and tested at least 100 specimens annually in the impact analysis, with a separate analysis taking into account site continuity. We compared proportions of acute gastroenteritis cases positive for rotavirus in the pre-vaccine and post-vaccine periods and calculated mean proportion changes for WHO regions, with 95% CIs; these findings were then compared with interrupted time series analyses. We did further sensitivity analyses to account for rotavirus vaccination coverage levels and sites that collected specimens for at least 11 months per year and tested at least 80 specimens per year. We also analysed the age distribution of rotavirus-positive cases before and after vaccine introduction.

Findings

403 140 children younger than 5 years of age admitted to hospital with acute gastroenteritis from 349 sites in 82 countries were enrolled over the study period, of whom 132 736 (32.9%) were positive for rotavirus. We included 305 789 children from 198 sites in 69 countries in the impact analysis. In countries that had not introduced rotavirus vaccine in their national immunisation programmes, rotavirus was detected in 38.0% (95% CI 4.8–73.4) of admissions for acute gastroenteritis annually whereas in those that have introduced the vaccine, rotavirus was detected in 23.0% (0.7–57.7) of admissions for acute gastroenteritis, showing a 39.6% (35.4–43.8) relative decline following introduction. Interrupted time series analyses confirmed these findings. Reductions by WHO regions ranged from 26.4% (15.0–37.8) in the Eastern Mediterranean Region to 55.2% (43.0–67.4) in the European Region and were sustained in nine countries (contributing up to 31 sites) for 6–10 years. The age distribution of children with rotavirus gastroenteritis shifted towards older children after rotavirus vaccine introduction.

Interpretation

A significant and sustained reduction in the proportion of hospital admissions for acute gastroenteritis due to rotavirus was seen among children younger than 5 years in GRSN sites following rotavirus vaccine introduction. These findings highlight the need to incorporate rotavirus vaccines into immunisation programmes in countries that have not yet introduced them and underline the importance of high-quality surveillance.

The control of diarrhea, the case of a rotavirus vaccine

[No disponible]

Prevalence and molecular typing of rotavirus in children with acute diarrhoea in Northeastern Colombia

After the introduction of the rotavirus vaccine, the number of rotavirus-associated deaths and the predicted annual rotavirus detection rate had slightly declined worldwide. Taking in account that in Colombia, Rotarix vaccine was introduced in 2009, the purpose of this study was to evaluate the presence of rotavirus A in children under five years who were treated for acute diarrhoea in Bucaramanga, Colombia and, moreover, to determine the genotypes of rotavirus present in those children. We performed an analytical cross-sectional study of rotavirus A in faecal samples from children up to five years of age. Stool samples were screened for rotavirus A using a lateral-flow immunochromatographic assay and confirmed using a VP6 sandwich ELISA. Genotyping of rotavirus A-positive samples was performed by PCR and sequencing of VP7 and VP4 genes. The overall prevalence of rotavirus was 30.53% (95% confidence interval [CI] 21.2 - 39.7). Most of the children with rotavirus (86.2%) had received two doses of the rotavirus vaccine. G3 strains accounted for the vast majority of cases (82.8%), followed by G12 strains (13.8%) and G3/G9 coinfections (3.4%). Among the P genotypes, P[8] was the most prevalent (69%), followed by P[9] (31%). The most common G[P] genotype combination was G3P[8], followed by G3P[9]. The main finding in this study was that rotavirus, in a Colombian region, is still an important pathogen in children under five years old, previously vaccinated. The results showed that different factors, such as kindergarten attendance, could explain the epidemiology and transmission of rotavirus in Bucaramanga.

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.

Vaccination herd effect experience in Latin America: a systematic literature review

Background: National pediatric vaccination programs have been introduced in Latin America (LatAm) to reduce the burden of diseases due to pathogens such as rotavirus, Haemophilus influenzae type b (Hib) and pneumococcus. Vaccination health benefits may extend to unvaccinated populations by reducing pathogen transmission. Understanding herd effect is important for implementation and assessment of vaccination programs. The objective was to conduct a systematic review of published epidemiological evidence of herd effect with Hib, rotavirus and pneumococcal conjugate vaccines (PCV) in LatAm.

Methods: Searches were conducted in PubMed, Virtual Health Library (VHL), SciELO and SCOPUS databases, for studies reporting data on herd effect from Hib, rotavirus and PCV vaccination in LatAm, without age restriction. Searches were limited to articles published in English, Spanish or Portuguese (1990–2016). After screening and full-text review, articles meeting the selection criteria were included to be critically appraised following criteria for observational and interventional studies. The presence of a herd effect was defined as a significant decrease in incidence of disease, hospitalization, or mortality.

Results: 3,465 unique articles were identified, and 23 were included (Hib vaccine n = 5, PCV n = 8, rotavirus vaccine n = 10). Most studies included children and/or adolescents (age range varied between studies). Studies in adults, including older adults (aged > 65 years), were limited. Few studies reported statistically significant reductions in disease incidence in age groups not targeted for vaccination. Hib-confirmed meningitis hospitalization decreased in children but herd effect could not be quantified. Some evidence of herd effect was identified for PCV and rotavirus vaccine in unvaccinated children. Evidence for herd effects due to PCV in adults was limited.

Conclusion: After introduction of Hib, PCV and rotavirus vaccination in LatAm, reductions in morbidity/mortality have been reported in children not targeted for vaccination. However, due to methodological limitations (e.g. short post-vaccination periods and age range studied), there is currently insufficient evidence to quantify the herd effect in adult populations. More research and higher quality surveillance is needed to characterize herd effect of these vaccines in LatAm.

Impact of monovalent rotavirus vaccine on diarrhoea-associated post-neonatal infant mortality in rural communities in Malawi: a population-based birth cohort study

BACKGROUND

Rotavirus is a major contributor to child mortality. The effect of rotavirus vaccine on diarrhoea mortality has been estimated in middle-income but not low-income settings, where mortality is high and vaccine effectiveness in reducing admissions to hospital is lower. Empirical population-based mortality studies have not been done in any setting. Malawi introduced monovalent rotavirus vaccine (RV1) in October, 2012. We aimed to investigate the impact and effectiveness of the RV1 vaccine in reducing diarrhoea-associated mortality in infants aged 10-51 weeks.

METHODS

In this population-based cohort study, we included infants born between Jan 1, 2012, and June 1, 2015, in Mchinji, Central Malawi and analysed data on those surviving 10 weeks. Individual vaccination status was extracted from caregiver-held records or report at home visits at 4 months and 1 year of age. Survival to 1 year was confirmed at home visit, or cause of death ascertained by verbal autopsy. We assessed impact (1 minus mortality rate ratio following vs before vaccine introduction) using Poisson regression. Among vaccine-eligible infants (born from Sept 17, 2012), we assessed effectiveness (1 minus hazard ratio) using Cox regression.

FINDINGS

Between Jan 1, 2012, and June 1, 2015, we recruited 48 672 livebirths in Mchinji, among whom 38 518 were vaccine-eligible and 37 570 survived to age 10 weeks. Two-dose versus zero-dose effectiveness analysis included 28 141 infants, of whom 101 had diarrhoea-associated death before 1 year of age. Diarrhoea-associated mortality declined by 31% (95% CI 1-52; p=0·04) after RV1 introduction. Effectiveness against diarrhoea-mortality was 34% (95% CI -28 to 66; p=0·22).

INTERPRETATION

RV1 was associated with substantial reduction in diarrhoea-associated deaths among infants in this rural sub-Saharan African setting. These data add considerable weight to evidence showing the impact of rotavirus vaccine programmes.

FUNDING

Wellcome Trust and GlaxoSmithKline Biologicals.

Impact of rotavirus vaccination on rotavirus hospitalisation rates among a resource-limited rural population in Mbita, Western Kenya

OBJECTIVES

A two-dose oral monovalent rotavirus vaccine (RV1) was introduced into the Kenyan National Immunization Program in July 2014. We assessed trends in hospitalisation for rotavirus-specific acute gastroenteritis (AGE) and strain distribution among children <5 years in a rural, resource-limited setting in Kenya before and after the nationwide implementation of the vaccine.

METHODS

Data on rotavirus AGE and strain distribution were derived from a 5-year hospital-based surveillance. We compared rotavirus-related hospitalisations and strain distribution in the 2-year post-vaccine period with the 3-year pre-vaccine baseline. Vaccine administrative data from the Unit of Vaccines and Immunization Services (UVIS) for Mbita sub-county were used to estimate rotavirus immunisation coverage in the study area.

RESULTS

We observed a 48% (95% CI: 27-64%) overall decline in rotavirus-related hospitalisations among children aged <5 years in the post-vaccine period. Coverage with the last dose of rotavirus vaccine increased from 51% in year 1% to 72% in year 2 of the vaccine implementation. Concurrently, reductions in rotavirus hospitalisations increased from 40% in the first year to 53% in the second year of vaccine use. The reductions were most pronounced among the vaccine-eligible group, with the proportion of cases in this age group dropping to 14% in post-vaccine years from a high of 51% in the pre-vaccine period. A diversity of rotavirus strains circulated before the introduction of the vaccine with G1P[8] being the most dominant strain. G2P[4] replaced G1P[8] as the dominant strain after the vaccine was introduced.

CONCLUSIONS

Rotavirus vaccination has resulted in a notable decline in hospital admissions for rotavirus infections in a rural resource-limited population in Kenya. This provides early evidence for continued use of rotavirus vaccines in routine childhood immunisations in Kenya. Our data also underscore the need for expanding coverage on second dose so as to maximise the impact of the vaccine.

Evaluation of the Influence of Gastrointestinal Coinfections on Rotavirus Vaccine Effectiveness in Botswana

BACKGROUND

Studies have demonstrated reduced rotavirus vaccine effectiveness (VE) in resource-limited settings. Enteropathogen coinfections in rotavirus cases have been hypothesized to contribute to the lower VE in such settings. We sought to determine if coinfections affect rotavirus VE in Botswana.

METHODS

Between June 2013 and April 2015, children <60 months old, presenting with severe gastroenteritis at 4 hospitals as part of a national rotavirus surveillance were enrolled. Rotavirus enzyme immunoassay (EIA)-positive samples were tested with an in-house real-time polymerase chain reaction (PCR) panel that detected 9 pathogens and a commercial 15 multiplex PCR gastrointestinal pathogen panel. Coinfection was defined as detection of rotavirus plus 1 of the 5 pathogens with the highest attributable fractions for diarrhea. Vaccine status was compared between rotavirus case patients and non-rotavirus "test-negative" controls. VE was also calculated restricting cases to those with rotavirus as the only pathogen detected.

RESULTS

Two hundred and forty-two children tested rotavirus EIA positive, and 368 children were negative. Of the 182 rotavirus EIA-positive samples tested with the gastrointestinal pathogen panel assay, coinfections were detected in 60 (33%). The overall adjusted 2-dose VE was 59% (95% confidence interval [CI]: 27-77) in the rotavirus coinfection group and 51% (95% CI: -14 to 79) in the rotavirus monoinfection subgroup. Using in-house multiplex PCR panel, of 213 rotavirus EIA-positive subjects, coinfections were detected in 98 samples (46%). The overall adjusted VEs for 2 doses were 48% (95% CI: -2 to 74) and 62% (95% CI: 25-80) in rotavirus monoinfection subgroup.

CONCLUSIONS

We could not find evidence of an effect of enteric coinfections on the effectiveness of rotavirus vaccine.

Reduction in Diarrhea- and Rotavirus-related Healthcare Visits Among Children <5 Years of Age After National Rotavirus Vaccine Introduction in Zimbabwe

BACKGROUND

In Zimbabwe, rotavirus accounted for 41%-56% of acute diarrhea hospitalizations before rotavirus vaccine introduction in 2014. We evaluated rotavirus vaccination impact on acute diarrhea- and rotavirus-related healthcare visits in children.

METHODS

We examined monthly and annual acute diarrhea and rotavirus test-positive hospitalizations and Accident and Emergency Department visits among children <60 months of age at 3 active surveillance hospitals during 2012-2016; we compared prevaccine introduction (2012-2013) with postvaccine introduction (2015 and 2016) data for 2 of the hospitals. We examined monthly acute diarrhea hospitalizations by year and age group for 2013-2016 from surveillance hospital registers and monthly acute diarrhea outpatient visits reported to the Ministry of Health and Child Care during 2012-2016.

RESULTS

Active surveillance data showed winter seasonal peaks in diarrhea- and rotavirus-related visits among children <60 months of age during 2012-2014 that were substantially blunted in 2015 and 2016 after vaccine introduction; the percentage of rotavirus test-positive visits followed a similar seasonal pattern and decrease. Hospital register data showed similar pre-introduction seasonal variation and post-introduction declines in diarrhea hospitalizations among children 0-11 and 12-23 months of age. Monthly variation in outpatient diarrhea-related visits mirrored active surveillance data patterns. At 2 surveillance hospitals, the percentage of rotavirus-positive visits declined by 40% and 43% among children 0-11 months of age and by 21% and 33% among children 12-23 months of age in 2015 and 2016, respectively.

CONCLUSION

Initial reductions in diarrheal illness among children <60 months of age, particularly among those 0-11 months of age, after vaccine introduction are encouraging. These early results provide evidence to support continued rotavirus vaccination and rotavirus surveillance in Zimbabwe.

Impact of rotavirus vaccination on rotavirus and all-cause gastroenteritis in peri-urban Kenyan children

A monovalent rotavirus vaccine (RV1) was introduced into the National Immunization Program in Kenya in July 2014. We examined the impact of the vaccine on hospitalization for all-cause acute gastroenteritis (AGE) and rotavirus-specific AGE and strain distribution at a large referral hospital which serves a predominantly peri-urban population in Central Kenya. Data on rotavirus AGE and strain distribution were derived from ongoing hospital-based AGE surveillance. Hospital administrative data were used to compare trends in all-cause AGE. Pre-vaccine (July 2009-June 2014) and post-vaccine (July 2014-June 2016) periods were compared for changes in hospitalization for all-cause AGE and rotavirus AGE and strain distribution. Following the vaccine introduction, the proportion of children aged <5years hospitalized for rotavirus declined by 30% (95% CI: 19-45%) in the first year and 64% (95% CI: 49-77%) in the second year. Reductions in rotavirus positivity were most pronounced among the vaccine-eligible group (<12months) in the first year post-vaccination at 42% (95% CI: 28-56%). Greater reductions of 67% (95% CI: 51-79%) were seen in the second year in the 12-23months age group. Similarly, hospitalizations for all-cause AGE among children <5years of age decreased by 31% (95% CI: 24-40%) in the first year and 58% (95% CI: 49-67%) in the second year of vaccine introduction. Seasonal peaks of rotavirus and all-cause AGE were reduced substantially. There was an increased detection of G2P[4], G3P[6] and G3P[8], which coincided temporally with the timing of the vaccine introduction. Thus, introducing the rotavirus vaccine into the routine immunization program in Kenya has resulted in a notable decline in rotavirus and all-cause AGE hospitalizations in Central Kenya. This provides early evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunizations.

Efficacy, safety and effectiveness of licensed rotavirus vaccines: a systematic review and meta-analysis for Latin America and the Caribbean

BACKGROUND

RotaTeq™ (RV5; Merck & Co. Inc., USA) and Rotarix™ (RV1, GlaxoSmithKline, Belgium) vaccines, developed to prevent rotavirus diarrhea in children under five years old, were both introduced into national immunization programs in 2006. As many countries in Latin America and the Caribbean have included either RV5 or RV1 in their routine childhood vaccination programs, we conducted a systematic review and meta-analysis to analyze efficacy, safety and effectiveness data from the region.

METHODS

We conducted a systematic search in PubMed, EMBASE, Scielo, Lilacs and the Cochrane Central Register, for controlled efficacy, safety and effectiveness studies published between January 2000 until December 2011, on RV5 and RV1 across Latin America (where both vaccines are available since 2006). The primary outcome measures were: rotavirus-related gastroenteritis of any severity; rotavirus emergency department visits and hospitalization; and severe adverse events.

RESULTS

The results of the meta-analysis for efficacy show that RV1 reduced the risk of any-severity rotavirus-related gastroenteritis by 65% (relative risk (RR) 0.35, 95% confidence interval (CI) 0.25; 0.50), and of severe gastroenteritis by 82% (RR 0.18, 95%CI 0.12; 0.26) versus placebo. In trials, both vaccines significantly reduced the risk of hospitalization and emergency visits by 85% (RR 0.15, 95%CI 0.09; 0.25) for RV1 and by 90% (RR 0.099, 95%CI 0.012; 0.77) for RV5. Vaccination with RV5 or RV1 did not increase the risk of death, intussusception, or other severe adverse events which were previously associated with the first licensed rotavirus vaccine. Real-world effectiveness studies showed that both vaccines reduced rotavirus hospitalization in the region by around 45-50% for RV5 (for 1 to 3 doses, respectively), and, by around 50-80% for RV1 (for 1 to 2 doses, respectively). For RV1, effectiveness against hospitalization was highest (around 80-96%) for children vaccinated before 12 months of age, compared with 5-60% effectiveness in older children. Both vaccines were most effective in preventing more severe gastroenteritis (70% for RV5 and 80-90% for RV1) and severe gastroenteritis (50% for RV5 and 70-80% for RV1).

CONCLUSION

This systematic literature review confirms rotavirus vaccination has been proven effective and well tolerated in protecting children in Latin America and the Caribbean.

Global, Regional, and National Estimates of Rotavirus Mortality in Children <5 Years of Age, 2000-2013

BACKGROUND

Rotavirus vaccine is recommended for routine use in all countries globally. To facilitate decision making on rotavirus vaccine adoption by countries, help donors prioritize investments in health interventions, and monitor vaccine impact, we estimated rotavirus mortality for children <5 years of age from 2000 to 2013.

METHODS

We searched PubMed using the keyword "rotavirus" to identify studies that met each of the following criteria: data collection midpoint in year 1998 or later, study period of a 12-month increment, and detection of rotavirus infection by enzyme immunoassay in at least 100 children <5 years of age who were hospitalized with diarrhea and systematically enrolled through active surveillance. We also included data from countries that participated in the World Health Organization (WHO)-coordinated rotavirus surveillance network between 2008 and 2013 that met these criteria. To predict the proportion of diarrhea due to rotavirus, we constructed a multiple linear regression model. To determine the number of rotavirus deaths in children <5 years of age from 2000 to 2013, we multiplied annual, country-specific estimates of the proportion of diarrhea due to rotavirus from the regression model by the annual number of WHO-estimated child deaths caused by diarrhea in each country.

RESULTS

Globally, we estimated that the number of rotavirus deaths in children <5 years of age declined from 528 000 (range, 465 000-591 000) in 2000 to 215 000 (range, 197 000-233 000) in 2013. The predicted annual rotavirus detection rate from these studies declined slightly over time from 42.5% (95% confidence interval [CI], 37.4%-47.5%) in 2000 to 37.3% (95% CI, 34.2%-40.5%) in 2013 globally. In 2013, an estimated 47 100 rotavirus deaths occurred in India, 22% of all rotavirus deaths that occurred globally. Four countries (India, Nigeria, Pakistan, and Democratic Republic of Congo) accounted for approximately half (49%) of all estimated rotavirus deaths in 2013.

DISCUSSION

While rotavirus vaccine had been introduced in >60 countries worldwide by the end of 2013, the majority of countries using rotavirus vaccine during the review period were low-mortality countries and the impact of rotavirus vaccine on global estimates of rotavirus mortality has been limited. Continued monitoring of rotavirus mortality rates and deaths through rotavirus surveillance will aid in monitoring the impact of vaccination.

Health Impact of Rotavirus Vaccination in Developing Countries: Progress and Way Forward

Two rotavirus vaccines have been licensed in >100 countries worldwide since 2006. As of October 2105, these vaccines have been implemented in the national immunization programs of 79 countries, including 36 low-income countries that are eligible for support for vaccine purchase from Gavi, the Vaccine Alliance. Rotavirus vaccines were initially introduced in Australia and countries of the Americas and Europe after completion of successful clinical trials in these regions, and the impact of routine vaccination in reducing the health burden of severe childhood gastroenteritis in these regions has been well documented. Because of concerns around the performance of orally administered rotavirus vaccines in developing countries, vaccine implementation in these settings only began after additional clinical trials were completed and the World Health Organization issued a global recommendation for use of rotavirus vaccines in 2009. This supplementary issue of Clinical Infectious Diseases includes a collection of articles describing the impact and effectiveness of routine rotavirus vaccination in developing countries that were among the early adopters of rotavirus vaccine. The data highlight the benefits of vaccination and should provide valuable evidence to sustain vaccine use in these countries and encourage other countries to adopt routine rotavirus vaccination to reduce the health burden of severe childhood gastroenteritis.

Effect of pentavalent rotavirus vaccine introduction on hospital admissions for diarrhoea and rotavirus in children in Rwanda: a time-series analysis

BACKGROUND

In May, 2012, Rwanda became the first low-income African country to introduce pentavalent rotavirus vaccine into its routine national immunisation programme. Although the potential health benefits of rotavirus vaccination are huge in low-income African countries that account for more than half the global deaths from rotavirus, concerns remain about the performance of oral rotavirus vaccines in these challenging settings.

METHODS

We conducted a time-series analysis to examine trends in admissions to hospital for non-bloody diarrhoea in children younger than 5 years in Rwanda between Jan 1, 2009, and Dec 31, 2014, using monthly discharge data from the Health Management Information System. Additionally, we reviewed the registries in the paediatric wards at six hospitals from 2009 to 2014 and abstracted the number of total admissions and admissions for diarrhoea in children younger than 5 years by admission month and age group. We studied trends in admissions specific to rotavirus at one hospital that had undertaken active rotavirus surveillance from 2011 to 2014. We assessed changes in rotavirus epidemiology by use of data from eight active surveillance hospitals.

FINDINGS

Compared with the 2009-11 prevaccine baseline, hospital admissions for non-bloody diarrhoea captured by the Health Management Information System fell by 17-29% from a pre-vaccine median of 4051 to 2881 in 2013 and 3371 in 2014, admissions for acute gastroenteritis captured in paediatric ward registries decreased by 48-49%, and admissions specific to rotavirus captured by active surveillance fell by 61-70%. The greatest effect was recorded in children age-eligible to be vaccinated, but we noted a decrease in the proportion of children with diarrhoea testing positive for rotavirus in almost every age group.

INTERPRETATION

The number of admissions to hospital for diarrhoea and rotavirus in Rwanda fell substantially after rotavirus vaccine implementation, including among older children age-ineligible for vaccination, suggesting indirect protection through reduced transmission of rotavirus. These data highlight the benefits of routine vaccination against rotavirus in low-income settings.

FUNDING

Gavi, the Vaccine Alliance and the Government of Rwanda.

A Systematic Review of the Effect of Rotavirus Vaccination on Diarrhea Outcomes Among Children Younger Than 5 Years

BACKGROUND

Rotavirus is the leading cause of vaccine-preventable diarrhea among children under 5 globally. Rotavirus vaccination has been shown to prevent severe rotavirus infections with varying efficacy and effectiveness by region.

METHODS

We sought to generate updated region-specific estimates of rotavirus vaccine efficacy and effectiveness. We systematically reviewed published vaccine efficacy and effectiveness studies to assess the region-specific effect of rotavirus vaccination on select diarrheal morbidity and mortality outcomes in children under 5 years of age. We employed meta-analytic methods to generate pooled effect sizes by Millennium Development Goal region.

RESULTS

Rotavirus vaccination was both efficacious and effective in preventing rotavirus diarrhea, severe rotavirus diarrhea and rotavirus hospitalizations among children under 5 across all regions represented by the 48 included studies. Efficacy against severe rotavirus diarrhea ranged from 90.6% [95% confidence interval (CI): 82.3-95.0] in the developed region to 88.4% (95% CI: 67.1-95.9) in Eastern/Southeastern Asia, 79.6% (95% CI: 71.3-85.5) in Latin America and the Caribbean, 50.0% (95% CI: 34.4-61.9) in Southern Asia and 46.1% (95% CI: 29.1-59.1) in sub-Saharan Africa. Region-specific effectiveness followed a similar pattern. There was also evidence of vaccine efficacy against severe diarrhea and diarrheal hospitalizations.

CONCLUSION

Our findings confirm the protective efficacy and effectiveness of rotavirus vaccination against rotavirus diarrheal outcomes among children under 5 globally.

Effectiveness of rotavirus vaccines against rotavirus infection and hospitalization in Latin America: systematic review and meta-analysis

Background

Rotavirus was the leading cause of childhood diarrhoea-related hospitalisations and death before the introduction of rotavirus vaccines.

Methods

We describe the effectiveness of rotavirus vaccines to prevent rotavirus infections and hospitalizations and the main rotavirus strains circulating before and after vaccine introduction through a systematic review and meta-analysis of studies published between 1990 and 2014. 203 studies were included to estimate the proportion of infections due to rotavirus and 10 to assess the impact of the vaccines. 41 of 46 studies in the post-vaccination period were used for meta-analysis of genotypes, 20 to calculate VE against infection, eight for VE against hospitalisation and seven for VE against severe rotavirus-diarrhoea.

Results

24.3 % (95 % CI 22.1–26.5) and 16.1 % (95 % CI 13.2–19.3) of cases of diarrhoea were due to rotavirus before and after vaccine introduction, respectively. The most prevalent G types after vaccine introduction were G2 (51.6 %, 95 % CI 38–65), G9 (14.5 %, 95 % CI 7–23) and G1 (14.2 %, 95 % CI 7–23); while the most prevalent P types were P[4] (54.1 %, 95 % CI 41–67) and P[8] (33 %, 95 % CI 22–46). G2P[4] was the most frequent genotype combination after vaccine introduction. Effectiveness was 53 % (95 % CI 46–60) against infection, 73 % (95 % CI, 66–78) against hospitalisation and 74 % (95 % CI, 68.0–78.0) against severe diarrhoea. Reductions in hospitalisations and mortality due to diarrhoea were observed in countries that adopted universal rotavirus vaccination.

Conclusions

Rotavirus vaccines are effective in preventing rotavirus-diarrhoea in children in Latin America. The vaccines were associated with changes in genotype distribution.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0173-2) contains supplementary material, which is available to authorized users.

Sustained Decrease in Gastroenteritis-related Deaths and Hospitalizations in Children Less Than 5 Years of Age After the Introduction of Rotavirus Vaccination: A Time-Trend Analysis in Brazil (2001-2010)

BACKGROUND

Rotavirus (RV) vaccine, Rotarix, was introduced into the Brazil national immunization program in 2006. To estimate population-level vaccine effect, we conducted a time-trend analysis on all-cause gastroenteritis (GE)-related death certificate-reported deaths (DCRDs), hospital deaths (HDs) and hospitalizations trends in <5-year-olds before and after RV vaccine introduction.

METHODS

National level all-cause GE-related death certificate [Mortality Information System] and admission (Hospital Information System) data were aggregated and analyzed. Negative-binomial regression models (adjusting for age, year and region) compared DCRDs, HDs and hospitalization trends in <5-year-olds between baseline (2001-2005) and postvaccine introduction periods (Mortality Information System: 2007-2009 and Hospital Information System: 2007-2010). Negative-binomial regression models were fitted to data for each outcome before 2006, and the predicted annual frequencies of each outcome were plotted against corresponding observed annual frequencies.

RESULTS

During the postvaccine introduction period, there was an overall age-independent GE-related DCRDs reduction (20.9%, P = 0.04) observed in children <5 years of age; a reduction was also seen in infants <1 year of age (20.8%, P = 0.003). Age-independent GE-related HDs and hospitalizations reductions (57.1%, P < 0.0001 and 26.6%, P < 0.0001, respectively) were observed in <5-year-olds; HDs reductions were also observed for each age group (<1-year-olds: 55.0%, P < 0.0001 and 1- to <5-year-olds: 59.5%, P < 0.0001). Observed annual frequencies of GE-related DCRDs, HDs and hospitalizations were lower than the predicted value in each age group in all years after 2006.

CONCLUSIONS

GE-related DCRDs, HDs and hospitalizations were significantly reduced in <1 and in 1- to <5-year-old Brazilian children after Rotarix introduction, which provides additional evidence of the direct and indirect population-level effect of RV vaccination on GE-related mortality and morbidity in children.

Potential safety issues and other factors that may affect the introduction and uptake of rotavirus vaccines

Rotavirus vaccines have demonstrated significant impact in reducing the burden of morbidity and mortality from childhood diarrhoea in countries that have implemented routine vaccination to date. Despite this success, in many countries, rotavirus vaccine coverage remains lower than that of other routine childhood vaccines. Several issues may potentially affect vaccine uptake, namely safety concerns related to intussusception with consequent age restrictions on rotavirus vaccination, contamination with porcine circovirus, vaccine-derived reassortant strains and hospitalization in newborn nurseries at time of administration of live oral rotavirus vaccine. In addition to these safety concerns, other factors may also affect uptake, including lower vaccine efficacy in the developing world, potential emergence of strains escaping from vaccine protection resulting in lower overall impact of a vaccination programme and sustainable vaccine financing. Although further work is needed to address some of these concerns, global policy bodies have reaffirmed that the benefits of rotavirus vaccination outweigh the risks, and vaccine use is recommended globally.

Methods and challenges for the health impact assessment of vaccination programs in Latin America

OBJECTIVE

To describe methods and challenges faced in the health impact assessment of vaccination programs, focusing on the pneumococcal conjugate and rotavirus vaccines in Latin America and the Caribbean.

METHODS

For this narrative review, we searched for the terms “rotavirus”, “pneumococcal”, “conjugate vaccine”, “vaccination”, “program”, and “impact” in the databases Medline and LILACS. The search was extended to the grey literature in Google Scholar. No limits were defined for publication year. Original articles on the health impact assessment of pneumococcal and rotavirus vaccination programs in Latin America and the Caribbean in English, Spanish or Portuguese were included.

RESULTS

We identified 207 articles. After removing duplicates and assessing eligibility, we reviewed 33 studies, 25 focusing on rotavirus and eight on pneumococcal vaccination programs. The most frequent studies were ecological, with time series analysis or comparing pre- and post-vaccination periods. The main data sources were: health information systems; population-, sentinel- or laboratory-based surveillance systems; statistics reports; and medical records from one or few health care services. Few studies used primary data. Hospitalization and death were the main outcomes assessed.

CONCLUSIONS

Over the last years, a significant number of health impact assessments of pneumococcal and rotavirus vaccination programs have been conducted in Latin America and the Caribbean. These studies were carried out few years after the programs were implemented, meet the basic methodological requirements and suggest positive health impact. Future assessments should consider methodological issues and challenges arisen in these first studies conducted in the region.

Value of Post-Licensure Data on Benefits and Risks of Vaccination to Inform Vaccine Policy: The Example of Rotavirus Vaccines

In 1999, the first rhesus-human reassortant rotavirus vaccine licensed in the U.S. was withdrawn within a year of its introduction after it was linked with intussusception at a rate of ~1 excess case per 10,000 vaccinated infants. While clinical trials of 60,000-70,000 infants of each of the two current live oral rotavirus vaccines, RotaTeq (RV5) and Rotarix (RV1), did not find an association with intussusception, post-licensure studies have documented a risk in several high and middle income countries, at a rate of ~1-6 excess cases per 100,000 vaccinated infants. However, considering this low risk against the large health benefits of vaccination that have been observed in many countries, including in countries with a documented vaccine-associated intussusception risk, policy makers and health organizations around the world continue to support the routine use of RV1 and RV5 in national infant immunization programs. Because the risk and benefit data from affluent settings may not be directly applicable to developing countries, further characterization of any associated intussusception risk following rotavirus vaccination as well as the health benefits of vaccination is desirable for low income settings.

Effectiveness of a monovalent rotavirus vaccine in infants in Malawi after programmatic roll-out: an observational and case-control study

Background

Rotavirus is the main cause of severe acute gastroenteritis in children in Africa. Monovalent human rotavirus vaccine (RV1) was added into Malawi's infant immunisation schedule on Oct 29, 2012. We aimed to assess the impact and effectiveness of RV1 on rotavirus gastroenteritis in the 2 years after introduction.

Methods

From Jan 1, 2012, to June 30, 2014, we recruited children younger than 5 years who were admitted into Queen Elizabeth Central Hospital, Blantyre, Malawi, with acute gastroenteritis. We assessed stool samples from these children for presence of rotavirus with use of ELISA and we genotyped rotaviruses with use of RT-PCR. We compared rotavirus detection rates in stool samples and incidence of hospital admittance for rotavirus in children from Jan 1 to June 30, in the year before vaccination (2012) with the same months in the 2 years after vaccination was introduced (2013 and 2014). In the case-control portion of our study, we recruited eligible rotavirus-positive children from the surveillance platform and calculated vaccine effectiveness (one minus the odds ratio of vaccination) by comparing infants with rotavirus gastroenteritis with infants who tested negative for rotavirus, and with community age-matched and neighbourhood-matched controls.

Findings

We enrolled 1431 children, from whom we obtained 1417 stool samples (99%). We detected rotavirus in 79 of 157 infants (50%) before the vaccine, compared with 57 of 219 (40%) and 52 of 170 (31%) in successive calendar years after vaccine introduction (p=0·0002). In the first half of 2012, incidence of rotavirus hospital admission was 269 per 100 000 infants compared with 284 in the same months of 2013 (rise of 5·8%, 95% CI −23·1 to 45·4; p=0·73) and 153 in these months in 2014 (a reduction from the prevaccine period of 43·2%, 18·0–60·7; p=0·003). We recruited 118 vaccine-eligible rotavirus cases (median age 8·9 months; IQR 6·6–11·1), 317 rotavirus-test-negative controls (9·4 months; 6·9–11·9), and 380 community controls (8·8 months; 6·5–11·1). Vaccine effectiveness for two doses of RV1 in rotavirus-negative individuals was 64% (95% CI 24–83) and community controls was 63% (23–83). The point estimate of effectiveness was higher against genotype G1 than against G2 and G12.

Interpretation

Routine use of RV1 reduced hospital admissions for several genotypes of rotavirus in children younger than 5 years, especially in infants younger than 1 year. Our data support introduction of rotavirus vaccination at the WHO recommended schedule, with continuing surveillance in high-mortality countries.

Funding

Wellcome Trust, GlaxoSmithKline Biologicals.

Ecological assessment of the direct and indirect effects of routine rotavirus vaccination in Merseyside, UK using data from multiple health systems: a study protocol

INTRODUCTION

Rotavirus is the most common cause of severe gastroenteritis in infants and young children worldwide. Currently 67 countries include rotavirus vaccine in childhood immunisation programmes, but uptake in Western Europe has been slow. In July 2013, rotavirus vaccine was introduced into the UK's routine childhood immunisation programme. Prior to vaccine introduction in the UK, rotavirus was estimated to result in 750,000 diarrhoea episodes and 80,000 general practice (GP) consultations each year, together with 45% and 20% of hospital admissions and emergency department attendances for acute gastroenteritis, in children under 5 years of age. This paper describes a protocol for an ecological study that will assess rotavirus vaccine impact in the UK, to inform rotavirus immunisation policy in the UK and in other Western European countries.

METHODS AND ANALYSIS

In Merseyside, UK, we will conduct an ecological study using a 'before and after' approach to examine changes in gastroenteritis and rotavirus incidence following the introduction of rotavirus vaccination. Data will be collected on mortality, hospital admissions, nosocomial infection, emergency department attendances, GP consultations and community health consultations to capture all healthcare providers in the region. We will assess both the direct and indirect effects of the vaccine on the study population. Comparisons of outcome indicator rates will be made in relation to vaccine uptake and socioeconomic status.

ETHICS AND DISSEMINATION

The study has been approved by NHS Research Ethics Committee, South Central-Berkshire REC Reference: 14/SC/1140. Study outputs will be disseminated through scientific conferences and peer-reviewed publications. The study will demonstrate the impact of rotavirus vaccination on the burden of disease from a complete health system perspective. It will identify key areas that require improved data collection tools to maximise the usefulness of this surveillance approach and will provide a template for vaccine evaluations using ecological methods in the UK.

Rotavirus vaccines in routine use

Vaccines are now available to combat rotavirus, the most common cause of severe diarrhea among children worldwide. We review clinical trial data for available rotavirus vaccines and summarize postlicensure data on effectiveness, impact, and safety from countries routinely using these vaccines in national programs. In these countries, rotavirus vaccines have reduced all-cause diarrhea and rotavirus hospitalizations by 17%-55% and 49%-92%, respectively, and all-cause diarrhea deaths by 22%-50% in some settings. Indirect protection of children who are age-ineligible for rotavirus vaccine has also been observed in some high and upper middle income countries. Experience with routine use of rotavirus vaccines in lower middle income countries has been limited to date, but vaccine introductions in such countries have been increasing in recent years. The risk-benefit analysis of rotavirus vaccines is extremely favorable but other strategies to improve the effectiveness of the vaccine, particularly in lower middle income settings, should be considered.

Rotavirus vaccines: current status and future considerations

Rotavirus is the leading cause of severe diarrhea among children<5 years worldwide. Currently licensed rotavirus vaccines have been efficacious and effective, with many countries reporting substantial declines in diarrheal and rotavirus-specific morbidity and mortality. However, the full public health impact of these vaccines has not been realized. Most countries, including those with the highest disease burden, have not yet introduced rotavirus vaccines into their national immunization programs. Research activities that may help inform vaccine introduction decisions include (1) establishing effectiveness, impact, and safety for rotavirus vaccines in low-income settings; (2) identifying potential strategies to improve performance of oral rotavirus vaccines in developing countries, such as zinc supplementation; and (3) pursuing alternate approaches to oral vaccines, such as parenteral immunization. Policy- and program-level barriers, such as financial implications of new vaccine introductions, should be addressed to ensure that countries are able to make informed decisions regarding rotavirus vaccine introduction.

Temporal trends in diarrhea-related hospitalizations and deaths in children under age 5 before and after the introduction of the rotavirus vaccine in four Latin American countries

INTRODUCTION

Rotavirus infection mainly affects children under 5 years of age and causes 453,000 deaths annually throughout the world. Several countries in Latin America have introduced the rotavirus vaccine and the majority have epidemiological data to measure impact following vaccine introduction.

OBJECTIVE

To assess the impact of rotavirus immunization on the number of all-cause diarrhea-related deaths and hospitalizations in children under 1 and 5 years of age in Bolivia, El Salvador, Honduras and Venezuela.

METHODS

Interrupted time-series analyzed with the integral method and the projection method to evaluate the pre and post-vaccine introduction trend in diarrheal disease compared to Argentina as the control country. The analysis period was from 2002 to 2010, including 2 to 4 post-vaccine years depending on the country. Information sources included records from PAHO, the Ministry of Health, public hospitals, social security, the private health system, the Expanded Programme on Immunization and UNPop 2008.

RESULTS

Over the period studied, reductions were observed in trends of diarrhea-related deaths and hospitalizations in children under five. In diarrhea-related deaths, under the integral method, the range of reduction was between 15.7% (13.5-17.9) and 56.8% (56.0-57.5) while with the projection method was between 19.9% (4.9-34.8) and 63.7%(56.1-71.4). In diarrhea-related hospitalizations, under the integral method was 5.6% (4.1-6.7) and 17.9% (16.7-19.1)) while with the projection method was between 5.1%(1.7-8.7) and 11.1% (5.8-16.3) CONCLUSIONS: A decrease was observed in the number of diarrhea related deaths and hospitalizations in all countries under study following introduction of the rotavirus vaccine as opposed to the control country. The impact on reduction of deaths was greater than hospitalization.

The human rotavirus vaccine Rotarix™ in infants: an integrated analysis of safety and reactogenicity

An integrated analysis of safety and reactogenicity data was undertaken for 28 randomized, placebo-controlled, double-blind Phase II and III trials (DBRCTs) of the oral live-attenuated human rotavirus vaccine, Rotarix™ (GlaxoSmithKline Vaccines). Healthy infants aged 6-20 wk received 2 or 3 doses of vaccine (n=56562) or placebo (n=45512) at 4- to 8-wk intervals. Solicited adverse events (AEs) were recorded for 8 d after each dose of vaccine or placebo. Unsolicited AEs, serious AEs (SAEs), and deaths were evaluated over 31-d post-vaccination follow-up periods. 95% confidence intervals (CIs) for the relative risk (RR) across studies excluding "1.0" signified potential imbalances between the 2 groups. The incidence of each solicited AE of any or Grade 3 severity was similar between groups. The incidence of all unsolicited AEs of any (RR=0.99 [95% CI: 0.94-1.04]; P=0.72) or Grade 3 severity (RR=0.91 [95% CI: 0.77-1.08]; P=0.31) was similar between groups. A significantly higher proportion of SAEs were reported in the placebo group compared with the vaccine group (RR=0.9 [95% CI: 0.82-0.98]; P=0.01). The incidence of death was low and similar between the 2 groups (0.13% in the vaccine group and 0.11% in the placebo group; RR=1.14 [95% CI: 0.78-1.68]; P=0.54). Very few cases of intussusception were reported (11 and 7 in the vaccine and placebo groups, respectively; RR=1.39 [95% CI: 0.49-4.27]; P=0.66). In conclusion, results of this analysis of DBRCTs show that the human rotavirus vaccine Rotarix™ has a reactogenicity and safety profile similar to placebo.

Investigation of a regulatory agency enquiry into potential porcine circovirus type 1 contamination of the human rotavirus vaccine, Rotarix: approach and outcome

In January 2010, porcine circovirus type 1 (PCV1) DNA was unexpectedly detected in the oral live-attenuated human rotavirus vaccine, Rotarix (GlaxoSmithKline [GSK] Vaccines) by an academic research team investigating a novel, highly sensitive analysis not routinely used for adventitious agent screening. GSK rapidly initiated an investigation to confirm the source, nature and amount of PCV1 in the vaccine manufacturing process and to assess potential clinical implications of this finding. The investigation also considered the manufacturer's inactivated poliovirus (IPV)-containing vaccines, since poliovirus vaccine strains are propagated using the same cell line as the rotavirus vaccine strain. Results confirmed the presence of PCV1 DNA and low levels of PCV1 viral particles at all stages of the Rotarix manufacturing process. PCV type 2 DNA was not detected at any stage. When tested in human cell lines, productive PCV1 infection was not observed. There was no immunological or clinical evidence of PCV1 infection in infants who had received Rotarix in clinical trials. PCV1 DNA was not detected in the IPV-containing vaccine manufacturing process beyond the purification stage. Retrospective testing confirmed the presence of PCV1 DNA in Rotarix since the initial stages of its development and in vaccine lots used in clinical studies conducted pre- and post-licensure. The acceptable safety profile observed in clinical trials of Rotarix therefore reflects exposure to PCV1 DNA. The investigation into the presence of PCV1 in Rotarix could serve as a model for risk assessment in the event of new technologies identifying adventitious agents in the manufacturing of other vaccines and biological products.

Group A rotavirus universal mass vaccination: how and to what extent will selective pressure influence prevalence of rotavirus genotypes?

Two human group A rotavirus (RVA) vaccines are available and highly effective in preventing severe gastroenteritis caused by all commonly circulating human RVA genotypes. The effect of universal mass vaccination on the RVA genotype distribution is discussed based on the knowledge of complete RVA genotype constellations, data from clinical efficacy trials and effectiveness studies, and genotype surveillance data from countries with universal mass vaccination programs. The theoretically predicted relative enrichment of RVA strains with the G2P[4] DS-1-like genotype constellation in regions with high coverage by Rotarix(®) (GlaxoSmithKline Biologicals, Rixensart, Belgium) seems to become apparent. A G3P[8] genotype increase, which was noted in several regions with a high coverage of RotaTeq(®) (Merck and Co., Inc., NJ, USA), is more difficult to explain based on the theoretical considerations.