Update on rotavirus vaccines

Novel viruses detected in bats in the Republic of Korea

Bats are natural reservoirs for potential zoonotic viruses. In this study, next-generation sequencing was performed to obtain entire genome sequences of picornavirus from a picornavirus-positive bat feces sample (16BF77) and to explore novel viruses in a pooled bat sample (16BP) from samples collected in South Korea, 2016. Fourteen mammalian viral sequences were identified from 16BF77 and 29 from 16BP, and verified by RT-PCR. The most abundant virus in 16BF77 was picornavirus. Highly variable picornavirus sequences encoding 3D^pol were classified into genera Kobuvirus, Shanbavirus, and an unassigned group within the family Picornaviridae. Amino acid differences between these partial 3D^pol sequences were ≥ 65.7%. Results showed that one bat was co-infected by picornaviruses of more than two genera. Retrovirus, coronavirus, and rotavirus A sequences also were found in the BP sample. The retrovirus and coronavirus genomes were identified in nine and eight bats, respectively. Korean bat retroviruses and coronavirus demonstrated strong genetic relationships with a Chinese bat retrovirus (RfRV) and coronavirus (HKU5-1), respectively. A co-infection was identified in one bat with a retrovirus and a coronavirus. Our results indicate that Korean bats were multiply infected by several mammal viruses.

Genetic characteristics and analysis of a novel rotavirus G3P[22] identified in diarrheic feces of Korean rabbit

Group A rotaviruses (RVAs) are important gastroenteric pathogens that infect humans and animals. This study aimed to analyze the complete genome sequence, i.e., 11 genome segments of the lapine rotavirus (LRV) identified in the intestine of a dead rabbit in the Republic of Korea (ROK) and to describe the genetic relationships between this lapine isolate [RVA/Rabbit-wt/KOR/Rab1404/2014/G3P[22] (Rab1404)] and other lapine isolates/strains. Rab1404 possessed the following genotype constellation: G3-P[22]-I2-R3-C3-M3-A9-N2-T3-E3-H3. The P[22] genotype was found to originate from rabbits and was for the first time identified in the ROK. Phylogenetic analysis showed that Rab1404 possessed VP1-3 and VP7 genes, which were closely related to those of the bat strain LZHP2; NSP1-4 genes, which were closely related to those of the simian strain RRV; and VP4, VP6, and NSP5 genes, which were closely related to the genes obtained from other rabbits. Interestingly, a close relationship between Rab1404 and simian RVA strain RVA/Simian-tc/USA/RRV/1975/G3P[3] for 8 gene segments was observed. RRV is believed to be a reassortant between bovine-like RVA strain and canine/feline RVA strains. Rab1404 and canine/feline RVAs shared the genes encoding VP1, VP3, VP7, NSP3, and NSP4. Additionally, the genome segments VP6 (I2), NSP1 (N2), and NSP5 (H3) of Rab1404 were closely related to those of bovine RVAs. This is the first report describing the complete genome sequence of an LRV detected in the ROK. These results indicate that Rab1404 could be a result of interspecies transmission, possibly through multiple reassortment events in the strains of various animal species and the subsequent transmission of the virus to a rabbit. Additional studies are required to determine the evolutionary source and to identify possible reservoirs of RVAs in nature.

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This is the first report to describe the complete genome sequence of a rabbit rotavirus (Rab1404) detected in the ROK.

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The 11 genome segments of Rab1404 were determined; G3-P[22]-I2-R3-C3-M3-A9-N2-T3-E3-H3.

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G3P[22] identified in this study is found to originate from rabbit and may have more species specificity.

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Rab1404 could be a result of multiple reassortment events from strains originating from various animal species and transmitted to the rabbit.

Mitigating bias in observational vaccine effectiveness studies using simulated comparator populations: Application to rotavirus vaccination in the UK

BACKGROUND

Measuring vaccine effectiveness (VE) relies on the use of observational study designs. However, achieving robust estimates of direct and indirect VE is frequently compromised by bias, particularly when using syndromic diagnoses of low-specificity.

METHODS

In order to mitigate confounding between the measured outcome and vaccine uptake, we developed a method to balance comparator populations using individual-level propensity scoring derived from the vaccine-exposed population, and applied it to the unexposed comparator population. Indirect VE was estimated by comparing the unvaccinated vaccine-exposed group with a propensity score-simulated unvaccinated, unexposed group. Direct VE was derived by removing indirect VE from the overall VE. We applied this method to an evaluation of the effectiveness of infant rotavirus vaccination in the UK. Using a general practice cohort of 45,259 live births between May 2010 and December 2015, we calculated indirect and direct VE against consultations for acute gastroenteritis using conventional and vaccination-propensity adjustment comparator populations.

RESULTS

The overall VE during the rotavirus-season (January-May) calculated using mixed-effects Cox regression was 30% [95% confidence intervals (95% CI: 25,35%)]. Use of conventional comparator populations resulted in implausible VE estimates -14% (95% CI: -41,7%) for direct and 29% (95% CI: 14,42%) for indirect effects. Applying our alternative method, direct VE was 26% (95% CI: 1,45%) and indirect VE was 8% (95% CI: -19,29%).

CONCLUSIONS

Estimating VE using propensity score simulated comparator populations, particularly for studies using routine health data with syndromic, low-specificity endpoints will aid accurate measurement of the broader public health impact of a vaccine programme.

The influence of incomplete case ascertainment on measures of vaccine efficacy

BACKGROUND

Motivated by the unexplained variation in the performance of some vaccines across different settings, we extend previous theoretical work to consider the potential impact of incomplete case ascertainment on measures of vaccine efficacy (VE), which is more likely in subclinical or clinically unimportant infections, such as rotavirus gastroenteritis.

METHODS

By simulating the measurement of VE under outbreak conditions using a discrete time stochastic SIR model, we compare three commonly used measures, VE_Risk, VE_Rate, and VE_Hazard, calculated respectively based on risk ratio, rate ratio and hazard ratio of disease. We investigate how these measures are influenced by factors such as biological activity, action mechanism of vaccine, proportion of cases ascertained, and underlying force of infection.

RESULTS

Under plausibly low levels of ascertainment, the group with the most infections, and therefore the most missed cases, has the most falsely inflated denominator, producing similar rates in the control and intervention groups. As a result, VE_Rate and VE_Hazard will underestimate the true VE compared to high case ascertainment scenarios. Furthermore, the extent of underestimation is greater for leaky vaccine models with lower biological protective effects and under conditions which are conducive to high transmission.

CONCLUSIONS

This study demonstrates that a biologically active vaccine may produce a low measured VE under a range of epidemiological, vaccine-related and logistical conditions. Low case ascertainment may partly explain the observed heterogeneity in the performance of rotavirus vaccine across different settings, and should be considered in the design and interpretation of future field trials.

Rotavirus vaccine impact and socioeconomic deprivation: an interrupted time-series analysis of gastrointestinal disease outcomes across primary and secondary care in the UK

BACKGROUND

Rotavirus causes severe gastroenteritis in infants and young children worldwide. The UK introduced the monovalent rotavirus vaccine (Rotarix®) in July 2013. Vaccination is free of charge to parents, with two doses delivered at 8 and 12 weeks of age. We evaluated vaccine impact across a health system in relation to socioeconomic deprivation.

METHODS

We used interrupted time-series analyses to assess changes in monthly health-care attendances in Merseyside, UK, for all ages, from July 2013 to June 2016, compared to predicted counterfactual attendances without vaccination spanning 3-11 years pre-vaccine. Outcome measures included laboratory-confirmed rotavirus gastroenteritis (RVGE) hospitalisations, acute gastroenteritis (AGE) hospitalisations, emergency department (ED) attendances for gastrointestinal conditions and consultations for infectious gastroenteritis at community walk-in centres (WIC) and general practices (GP). All analyses were stratified by age. Hospitalisations were additionally stratified by vaccine uptake and small-area-level socioeconomic deprivation.

RESULTS

The uptake of the first and second doses of rotavirus vaccine was 91.4% (29,108/31,836) and 86.7% (27,594/31,836), respectively. Among children aged < 5 years, the incidence of gastrointestinal disease decreased across all outcomes post-vaccine introduction: 80% (95% confidence interval [CI] 70-87%; p < 0.001) for RVGE hospitalisation, 44% (95% CI 35-53%; p < 0.001) for AGE hospitalisations, 23% (95% CI 11-33%; p < 0.001) for ED, 32% (95% CI 7-50%; p = 0.02) for WIC and 13% (95% CI -3-26%; p = 0.10) for GP. The impact was greatest during the rotavirus season and for vaccine-eligible age groups. In adults aged 65+ years, AGE hospitalisations fell by 25% (95% CI 19-30%; p < 0.001). The pre-vaccine risk of AGE hospitalisation was highest in the most socioeconomically deprived communities (adjusted incident rate ratio 1.57; 95% CI 1.51-1.64; p < 0.001), as was the risk for non-vaccination (adjusted risk ratio 1.54; 95% CI 1.34-1.75; p < 0.001). The rate of AGE hospitalisations averted per 1,000 first doses of vaccine was higher among infants in the most deprived communities compared to the least deprived in 2014/15 (28; 95% CI 25-31 vs. 15; 95% CI 12-17) and in 2015/16 (26; 95% CI 23-30 vs. 13; 95% CI 11-16).

CONCLUSIONS

Following the introduction of rotavirus vaccination, incidence of gastrointestinal disease reduced across the health-care system. Vaccine impact was greatest among the most deprived populations, despite lower vaccine uptake. Prioritising vaccine uptake in socioeconomically deprived communities should give the greatest health benefit in terms of population disease burden.

Population effectiveness of the pentavalent and monovalent rotavirus vaccines: a systematic review and meta-analysis of observational studies

BACKGROUND

Rotavirus was the leading cause of acute gastroenteritis (AGE) in infants and young children prior to the introduction of routine vaccination. Since 2006 there have been two licensed vaccines available; with successful clinical trials leading the World Health Organization to recommend rotavirus vaccination for all children worldwide. In order to inform immunisation policy we have conducted a systematic review and meta-analysis of observation studies to assess population effectiveness against acute gastroenteritis.

METHODS

We systematically searched PubMed, Medline, Web of Science, Cinhal and Academic Search Premier and grey literature sources for studies published between January 2006 and April 2014. Studies were eligible for inclusion if they were observational measuring population effectiveness of rotavirus vaccination against health care attendances for rotavirus gastroenteritis or AGE. To evaluate study quality we use used the Newcastle-Ottawa Scale for non-randomised studies, categorising studies by risk of bias. Publication bias was assessed using funnel plots. If two or more studies reported a measure of vaccine effectiveness (VE), we conducted a random effects meta-analysis. We stratified analyses by World Bank country income level and used study quality in sensitivity analyses.

RESULTS

We identified 30 studies, 19 were from high-income countries and 11 from middle-income countries. Vaccine effectiveness against hospitalization for laboratory confirmed rotavirus gastroenteritis was highest in high-income countries (89% VE; 95% CI 84-92%) compared to middle-income countries (74% VE; 95% CI 67-80%). Vaccine effectiveness was higher for those receiving the complete vaccine schedule (81% VE; 95% CI 75-86%) compared to partial schedule (62% VE; 95% CI 55-69%). Two studies from high-income countries measured VE against community consultations for AGE with a pooled estimate of 40% (95% CI 13-58%; 2 studies).

CONCLUSIONS

We found strong evidence to further support the continued use of rotavirus vaccines. Vaccine effectiveness was similar to that reported in clinical trials for both high and middle-income countries. There is limited data from Low income settings at present. There was lower effectiveness against milder disease. Further studies, should continue to report effectiveness against AGE and less-severe rotavirus disease because as evidenced by pre-vaccine introduction studies this is likely to contribute the greatest burden on healthcare resources, particularly in high-income countries.

Current status of rotavirus vaccines

BACKGROUND

Rotaviruses remain the major cause of childhood diarrheal disease worldwide and of diarrheal deaths of infants and children in developing countries. The huge burden of childhood rotavirus-related diarrhea in the world continues to drive the remarkable pace of vaccine development.

DATA SOURCES

Research articles were searched using terms "rotavirus" and "rotavirus vaccine" in MEDLINE and PubMed. Articles not published in the English language, articles without abstracts, and opinion articles were excluded from the review. After preliminary screening, all articles were reviewed and synthesized to provide an overview of current vaccines and vaccination programs.

RESULTS

In this review of the global rotavirus vaccines and vaccination programs, the principles of rotavirus vaccine development and the efficacy of the currently licensed vaccines from both developed and developing countries were summarized.

CONCLUSIONS

Rotavirus is a common cause of diarrhea in children in both developed and developing countries. Rotavirus vaccination is a cost-effective measure to prevent rotavirus diarrhea.

Disease caused by rotavirus infection

Although rotavirus vaccines are available, rotaviruses remain the major cause of childhood diarrheal disease worldwide. The Rotarix (GlaxoSmithKline Biologicals Rixensart, Belgium) and RotaTeq (Merck and Co., Inc. Whitehouse Station, New Jersey, USA) vaccines are effective for reducing the morbidity and mortality of rotavirus infection. This article aims to assess the epidemiology of rotaviral gastroenteritis and the efficacy and effectiveness of licensed rotavirus vaccines. This review concludes by presenting challenges in the field that require further exploration by and perspectives from basic and translational research in the future.

Distribution of rotavirus strains and strain-specific effectiveness of the rotavirus vaccine after its introduction: a systematic review and meta-analysis

BACKGROUND

Concerns exist about whether monovalent (RV1) and pentavalent (RV5) rotavirus vaccines provide adequate protection against diverse strains and whether vaccine introduction will lead to selective pressure. We aimed to investigate the distribution of rotavirus strains and strain-specific rotavirus vaccine effectiveness after vaccine introduction.

METHODS

We did a systematic review of published work to assess the strain-specific effectiveness of RV1 and RV5 rotavirus vaccines. We classified strains as homotypic, partly heterotypic, and fully heterotypic based on the amount of antigen-matching between strain and vaccine. When studies reported vaccine effectiveness against single antigens (G-type or P-type), we categorised them as either single-antigen vaccine type or single-antigen non-vaccine type. Our primary outcome was strain-specific vaccine effectiveness, comparing effectiveness of homotypic strains with fully or partly heterotypic strains. A secondary outcome was the prevalence of rotavirus strains after vaccine introduction. We estimated pooled odds ratios using random-effect regression models, stratified by country income level and vaccine type, and tested for differences in strain-specific vaccine effectiveness. We assessed strain distribution trends from surveillance reports.

FINDINGS

In high-income countries, RV1 pooled vaccine effectiveness was 94% (95% CI 80-98) against homotypic strains, 71% (39-86) against partly heterotypic strains, and 87% (76-93) against fully heterotypic strains. In middle-income settings, respective pooled data were 59% (36-73), 72% (58-81), and 47% (28-61). In high-income countries, RV5 vaccine effectiveness was 83% (78-87) against homotypic strains, 82% (70-89) against single-antigen vaccine type strains, 82% (70-89) against partly heterotypic strains, and 75% (47-88) against single-antigen non-vaccine type strains. In middle-income settings, RV5 vaccine effectiveness was 70% (58-78) against single-antigen vaccine type strains, 37% (10-56) against partly heterotypic strains, and 87% (38-97) against single-antigen non-vaccine type strains. No difference was noted in vaccine effectiveness for either RV1 or RV5 in any setting (all p>0·05). Prevalent strains in countries using RV1 were G2P[4] (2198 of 4428, 50%) and G1P[8] (953, 22%), and those in countries using RV5 were G1P[8] (1280 of 3875, 33%) and G2P[4] (1169, 30%). Sustained predominance of a single strain was not recorded.

INTERPRETATION

RV1 and RV5 exert similar effectiveness against homotypic and heterotypic rotavirus strains. Persistence of specific strains was not recorded, suggesting vaccine-induced selective pressure did not occur. Expansion of rotavirus surveillance efforts to low-income countries and ongoing surveillance are crucial to identify emergence of new strains and to assess strain-specific vaccine effectiveness in various settings.

FUNDING

None.

Comparison between febrile and afebrile seizures associated with mild rotavirus gastroenteritis

PURPOSE

We aimed on identifying the differences of febrile and afebrile seizures associated with mild rotavirus gastroenteritis (RVGE) in the pediatric population.

METHOD

Medical charts of pediatric patients who had been admitted between July 1999 and June 2011 due to RVGE were retrospectively reviewed. Subjects were ultimately divided into three groups; 'no seizure' (NS: patients without seizure), 'febrile seizure' (FS: patients with fever during seizure), 'afebrile seizure' (AFS: patients without fever during seizure). Comparisons between groups were carried out on demographic and clinical characteristics, laboratory test results, electroencephalogram findings, brain magnetic resonance imaging findings, antiepileptic treatment, and prognosis.

RESULTS

Among the 755 subjects who had been admitted due to mild rotavirus enteritis, 696 (90.3%) did not have any seizures, 17 (2.2%) had febrile seizures, 42 (5.5%) had afebrile seizures. The duration of gastrointestinal symptoms before the onset of seizures were significantly shorter in the FS group compared to the AFS group (1.3±0.8 vs. 2.8±1.0 days; p<0.0001). A single seizure attack was significantly higher in the AFS group (3.0±1.6 vs. 1.7±1.0 episodes; p=0.0003), and the frequency of seizures that were of focal type with or without secondary generalization were significantly higher in the AFS group (33.3% vs. 6.0%; p=0.0139). All patients among the FS and AFS group had not received further antiepileptic treatment after discharge, and none developed epilepsy during follow up period.

CONCLUSION

Despite some differences in seizure characteristics, both febrile and afebrile seizures associated with mild RVGE were mostly benign with a favorable prognosis.

Rotavirus vaccination in developing countries

Although two oral rotavirus vaccines are licensed in many countries, multiple factors may affect decision-making regarding introduction into national immunization programs in developing countries. Financial and logistic challenges to introduction of rotavirus vaccines in countries with limited infrastructure and resources are accompanied by a perceived lack of need and evidence from recent vaccine trials, which demonstrated significantly lower efficacy in high burden countries. Nonetheless, even at a low efficacy, the use of existing vaccines in developing countries is predicted to alleviate considerable rotavirus disease burden and mortality. Potential alternate strategies for improving response to existing vaccines or the development of improved vaccines need to be considered to ensure that the remaining burden of mortality and morbidity can be addressed in the future.

Accounting for model uncertainty in estimating global burden of disease

OBJECTIVE

To illustrate the effects of failing to account for model uncertainty when modelling is used to estimate the global burden of disease, with specific application to childhood deaths from rotavirus infection.

METHODS

To estimate the global burden of rotavirus infection, different random-effects meta-analysis and meta-regression models were constructed by varying the stratification criteria and including different combinations of covariates. Bayesian model averaging was used to combine the results across models and to provide a measure of uncertainty that reflects the choice of model and the sampling variability.

FINDINGS

In the models examined, the estimated number of child deaths from rotavirus infection varied between 492,000 and 664,000. While averaging over the different models' estimates resulted in a modest increase in the estimated number of deaths (541,000 as compared with the World Health Organization's estimate of 527,000), the width of the 95% confidence interval increased from 105,000 to 198,000 deaths when model uncertainty was taken into account.

CONCLUSION

Sampling variability explains only a portion of the overall uncertainty in a modelled estimate. The uncertainty owing to both the sampling variability and the choice of model(s) should be given when disease burden results are presented. Failure to properly account for uncertainty in disease burden estimates may lead to inappropriate uses of the estimates and inaccurate prioritization of global health needs.

Performance of rotavirus vaccines in developed and developing countries

The World Health Organization estimates that rotavirus diarrhea results in approximately half a million deaths and approximately 2.4 million hospitalizations in developing countries each year. Two live oral rotavirus vaccines, RotaTeq® (RV 5; Merck) and Rotarix® (RV 1; GlaxoSmithKline) with good efficacy against severe rotavirus disease and a reassuring safety profile could substantially impact the burden of rotavirus disease. In April 2009, WHO provided a recommendation for global introduction of these vaccines in national immunization programs of developing countries worldwide. In this article, we review published data on previous candidate rotavirus vaccines and vaccines in current use, with emphasis on their performance in developed versus developing countries. In developed countries, both first and second generation rotavirus vaccines have demonstrated high efficacy against severe rotavirus disease (pooled efficacy = 73% and 85%, respectively). In developing countries, small early trials for the first generation vaccines failed to provide protection against rotavirus disease (pooled efficacy = 20%), however, trials of the second generation vaccines yielded substantial improvements in efficacy in developing countries (pooled efficacy of 51%), leading to a global recommendation for rotavirus vaccine introduction by WHO. Future efforts for these vaccines should focus on optimizing the efficacy and delivery of these vaccines in challenging target populations of Asia and Africa with the greatest burden of severe rotavirus disease.

Rotavirus infection: a perspective on epidemiology, genomic diversity and vaccine strategies

For centuries, acute diarrhea has been a major cause of death in young children worldwide, and until 1973, before rotavirus was discovered; no infectious agents could be identified in about 80% of patients admitted to hospital with severe dehydrating diarrhea. Rotaviruses have now been shown to cause 40-50% of severe acute diarrhea in young children worldwide in both developing and developed countries. More than 600,000 young children die and approximately 2.4 million hospitalize annually from rotavirus disease, especially in South-East Asia and sub-Saharan Africa. Two safe and effective vaccines are now licensed in 100 countries but used in 17 countries. Rotarix (GSK) vaccine is derived from single attenuated human rotavirus G1P[8], representative of the most common serotype identified worldwide. RotaTeq (Merck) is a pentavalent mixture of naturally attenuated bovine/human rotavirus reassortants representing G1, G2, G3, G4, and P[8] serotypes. Though these vaccines have already dramatically decreased the morbidity associated with rotavirus in countries where they are widely used, the third generation of vaccines, based on inactivated viruses or recombinant virus like particle are already in pipeline. Continuous surveillance and the genetic and antigenic analysis of the various strains of rotavirus circulating worldwide will aid significantly in assessing the effectiveness of these vaccines and monitor emergence of new strains. Introduction of rotavirus vaccines in national vaccine policy along with other childhood vaccines may result in significant reduction in mortality in children in poor socioeconomic countries.

Effectiveness of rotavirus vaccination against childhood diarrhoea in El Salvador: case-control study

OBJECTIVE

To evaluate the effectiveness of a monovalent rotavirus vaccine against severe rotavirus disease and to assess its impact on diarrhoea in children aged less than 2 years after national introduction in El Salvador, a low-middle income country in Central America.

DESIGN

Matched case-control study.

SETTING

Seven hospitals in cities across El Salvador, January 2007 to June 2009.

PARTICIPANTS

323 children aged less than 2 years admitted with laboratory confirmed rotavirus diarrhoea and 969 healthy controls matched for age and neighbourhood.

MAIN OUTCOME MEASURE

Effectiveness of rotavirus vaccination ((1-adjusted odds ratio of vaccination)x100) against rotavirus diarrhoea requiring hospital admission.

RESULTS

Cases and controls were similar for breast feeding, premature birth, maternal education, and socioeconomic variables. G1P[8] strains were identified in 92% of rotavirus cases. Effectiveness of two doses of vaccination against diarrhoea requiring hospital admission was 76% (95% confidence interval 64% to 84%). Protection was significantly lower (P=0.046) among children aged 12 months or more (59%, 27% to 77%) compared with children aged 6-11 months (83%, 68% to 91%). One dose of vaccine was 51% (26% to 67%) effective. At the sentinel hospitals, all admissions for diarrhoea among children under 5 declined by 40% in 2008 and by 51% in 2009 from the prevaccine year 2006.

CONCLUSIONS

A monovalent rotavirus vaccine was highly effective against admissions for rotavirus diarrhoea in children aged less than 2 years in El Salvador and substantially reduced the number of such admissions in this low-middle income setting. The impact on disease epidemiology after vaccination, particularly among older children, warrants future attention.

The effect of rotavirus vaccine on diarrhoea mortality

Background Approximately 39% of the global diarrhoea deaths in children aged 5 years may be attributable to rotavirus infection. Two rotavirus vaccines were recently introduced to the market, with evidence of efficacy in the USA, Europe and Latin America. We sought to estimate the effectiveness of these vaccines against rotavirus morbidity and mortality.

Methods We conducted a systematic review of published efficacy and effectiveness trials of rotavirus vaccines. Study descriptors and outcome measures were abstracted into standardized tables and the quality of each study was graded. We performed meta-analyses for any outcome with two or more data points, and used child health epidemiology reference group (CHERG) Rules for Evidence Review to estimate the effect of the vaccine on rotavirus mortality.

Results We identified six papers for abstraction, reporting results from four studies. No studies reported diarrhoea or rotavirus deaths, but all studies showed reductions in hospitalizations due to rotavirus or diarrhoea of any aetiology, severe and any rotavirus infections and diarrhoea episodes of any aetiology in children who received rotavirus vaccine compared with placebo. Effectiveness against very severe rotavirus infection best approximated effectiveness against the fraction of diarrhoea deaths attributable to rotavirus, and was estimated to be 74% (95% confidence interval: 35–90%).

Conclusions Rotavirus vaccines are efficacious against rotavirus morbidity and mortality and have the potential to substantially reduce child mortality in low-income countries if implemented appropriately.

Oral rotavirus vaccines: how well will they work where they are needed most?

Rotavirus vaccines hold promise to decrease the burden of severe diarrhea in the poorest countries, where 85% of deaths due to rotavirus occur. However, the potency of live oral vaccines is lower in these challenging settings than in middle- and upper-income countries. Many hypotheses have been suggested to explain these differences that could provide clues to improve the ultimate success of these novel vaccines. Although introduction today of even moderately effective vaccines will decrease the morbidity and mortality associated with rotavirus in low-income settings, research is urgently needed to understand why these differences in efficacy occur and what could be done to improve vaccine performance to maximize the life-saving benefits of vaccination.

Rotavirus infection and intussusception in Tunisian children: implications for use of attenuated rotavirus vaccines

BACKGROUND

A licensed rotavirus vaccine was withdrawn from use because of an increased risk of intussusception. The association of rotavirus vaccination with intussusception raised concerns about a potential link between natural rotavirus disease and intussusception. The objectives of the present study were to determine whether an epidemiological association with natural rotavirus infection existed.

METHODS

From 1984 to 2003, all children younger than 5 years with intussusception were retrospectively identified by medical charts, and from 1995 to 2003, a prospective surveillance study of rotavirus infection in children younger than 5 years was independently conducted. Epidemiological characteristics of intussusception and rotavirus infection were then compared.

RESULTS

A total of 533 cases of intussusception and 146 cases of rotavirus infection were identified. The incidence of intussusception for infants younger than 1 year was 62/100,000 child-years. The age distributions of intussusception and rotavirus gastroenteritis overlapped, and a masculine predominance was noted in both cases. No significant association was observed between the monthly distribution of intussusception and rotavirus infection.

CONCLUSION

The present study has not convincingly shown that rotavirus diarrhea plays a major role in intussusception. However, data about age and sex distributions supported the biologic plausibility of such an association.

The burden of rotavirus hospitalizations among Medicaid and non-Medicaid children younger than 5 years old

OBJECTIVES

We sought to compare the burden of hospitalizations associated with rotavirus gastroenteritis (RGE) in children younger than 5 years in US Medicaid and non-Medicaid populations in 2000 and 2003.

METHODS

We used the Kids' Inpatient Database (KID) to examine the burden of RGE-associated hospitalizations in terms of numbers and rates of hospitalizations, lengths of stay, and hospital charges. Two indirect methods were also used to estimate RGE-associated hospitalizations, because rotavirus testing is not routinely performed.

RESULTS

Approximately 40% of children younger than 5 years were enrolled in Medicaid in 2003, but this population accounted for nearly 50% of all RGE-associated hospitalizations and 60% of total charges. Children enrolled in Medicaid had significantly greater hospitalization rates, average lengths of stay, and average charges per stay than did those not enrolled.

CONCLUSIONS

Although RGE affects all socioeconomic groups, the Medicaid population accounted for a disproportionate number of the hospitalizations. With the inclusion of rotavirus vaccines in the pediatric immunization schedule, it is important that US children, especially those enrolled in Medicaid programs, are vaccinated to reduce the burden of RGE.

Changing epidemiology of rotavirus-related hospitalizations in rio de janeiro, Brazil, from 2002 to 2006

A prospective hospital-based sentinel study conducted in Rio de Janeiro identified a shift in the pattern (long to short electropherotype and P(8) to P(4) genotype) of rotavirus strains recovered from children with severe diarrhea a few months after the far-reaching Brazilian rotavirus immunization program was launched, posing new interesting challenges.

Rotavirus enteritis in solid organ transplant recipients: an underestimated problem?

BACKGROUND

Diarrhea in solid organ transplantation can be a complication with a high morbidity and mortality. Rotavirus (RV) infection normally occurs in children up to 3 years of age and often presents with severe diarrhea; however, it can also affect adults. We investigated the prevalence and outcome of RV infections in both adult and pediatric patients after solid organ transplantation.

PATIENTS AND METHODS

Retrospective analysis of RV-related enteritis in solid organ transplant recipients with a minimum of a 1-year follow-up from a single center between 2000 and 2004.

RESULTS

Within our cohort of 1303 solid organ transplants, RV infection was observed in 19 patients (1.5%); 14 of these were liver recipients. Infection was most prevalent among pediatric liver recipients, with 52% (11/21) of the children affected. Five adults acquired the infection during their initial hospitalization. Two adult patients had to be readmitted following late-onset RV infection. In all cases, infection was self-limiting, but led to prolonged hospitalization because of significant loss of fluids and electrolytes.

CONCLUSIONS

RV enteritis is a common infection in pediatric solid organ recipients but may also affect adult patients.

Rotavirus and rotavirus vaccines

Two new rotavirus vaccines have recently been licensed that will provide the intervention needed to diminish the huge burden of rotavirus disease among all children. In many upper and middle income countries, these vaccines will soon be available for the routine immunization of children. The impact should be a rapid and measurable reduction in hospitalizations and doctor visits for acute diarrhea in children, especially in the winter rotavirus season. While few deaths occur in these settings, the illness has consequences in terms of both medical costs and indirect costs, including parents work time lost. In the developing world, clinical trials are still needed to ensure that the vaccines being licensed will work as expected in children living in poor settings. In these settings, other enteric flora, micronutrient malnutrition, higher titers of maternal antibody and other factors still poorly defined have compromised other live oral vaccines and have required the developers to alter vaccine formulation, dose, or schedule. Until these trials are completed, we can only hope that the efficacy will be comparable and that the vaccine will prove to be life-savers. Once the efficacy and safety have been established, rotavirus vaccines could provide a major boost to programs for child survival.

The Epidemiology of Paediatric Intussusception in Singapore: 1997 to 2004

Introduction: The world’s first rotavirus vaccine, Rotashield® or RRV-TV, was registered in the US in 1998, but withdrawn within a year because of an observed association with intussusception (IS). Surveillance for IS has consequently become important in safety monitoring of new-generation rotavirus vaccines during development. Post-marketing surveillance is also important, and requires the availability of local baseline epidemiology data on IS. Materials and Methods: An eight-year study of IS in children under 2 years of age in Singapore was performed by retrospective review of admissions to KK Women’s and Children’s Hospital, the main paediatric hospital, from 1997 to 2001, followed by prospective surveillance of all hospitals from 2001 to 2004, using the case definition of the Brighton Collaboration Intussusception Working Group. Results: The average IS incidence was 60 per 100,000 in under-ones, and 32 per 100,000 in under-twos, with a downward trend between 1999 and 2004. Ninety-two per cent of subjects were aged below one year, with 51% aged 6 months to 11 months. The mean age at which IS occurred increased from 6.4 months to 12.5 months over the study period. The male-to-female ratio was 1.3:1. No trend in IS numbers was observed over different months of the year. Conclusion: IS in Singapore shows no seasonality, but has demonstrated a trend of decreasing incidence in recent years. While highest in the first year of life, the risk of IS is increasing in the second year of life. Males have a slightly higher risk. Key words: Adverse effects, Rotavirus vaccines