The incidence and direct medical cost of hospitalization due to rotavirus gastroenteritis in Kyoto, Japan, as estimated from a retrospective hospital study

Effectiveness of rotavirus vaccines against hospitalisations in Japan

BACKGROUND

In Japan, rotavirus hospitalisation occurs at a rate from 2.8 to 13.7 per 1000 child-years among children age less than 5 years, and it imposes a substantial burden to the healthcare system in the country. While both monovalent (RV1) and pentavalent (RV5) rotavirus vaccines are licensed in Japan, neither has been incorporated in the national infant immunization programme. In this study, we estimated vaccine effectiveness (VE) in Japan.

METHODS

This study was conducted in Yuri-Kumiai General Hospital located in a city in the north-western part of Japan. Age-eligible children for rotavirus vaccination were enrolled if they were hospitalized for rotavirus gastroenteritis between September 2013 and August 2016. Rotavirus gastroenteritis was defined by the detection of rotavirus antigen by immunochromatography. "Vaccinated" was defined as infant inoculated with at least one dose of either RV1 or RV5. A conditional logistic regression analysis was performed by modelling the year of birth, year of admission, residence of the children and vaccination status, and by matching the age of cases with that of test-negative controls. The adjusted odds ratio of the vaccinated over unvaccinated was then used to calculate VE in the formula of (1 - adjusted odds ratio) × 100.

RESULTS

Out of the 244 patients enrolled, rotavirus antigen was detected in 55 (22.5%) of whom 10 (18.2%) were vaccinated, whereas 94 (49.7%) of 189 test-negative controls were vaccinated. During the study period, the vaccine uptake rate in the controls increased from 36.2% to 61.8%. On the other hand, the vaccination coverage over the three years was 64.2% in Yuri-Honjo city (three quarters of the catchment), and 91.4% in Nikaho city (one quarter of the catchment). The VE was calculated to be 70.4% (95% confidence interval: 36.0-86.4%, P = 0.002). The point estimate of the VE was lower but its 95% confidence interval overlaps those of the efficacies obtained from clinical trials in Japan.

CONCLUSION

The rotavirus vaccine was effective in the real-world setting in Japan as in the clinical trials, and the introduction of rotavirus vaccine in the national infant immunization schedule will substantially reduce the number of rotavirus gastroenteritis hospitalisation in Japan.

Concomitant administration of diphtheria, tetanus, acellular pertussis and inactivated poliovirus vaccine derived from Sabin strains (DTaP-sIPV) with pentavalent rotavirus vaccine in Japanese infants

Rotavirus is the leading cause of severe acute gastroenteritis in infants and young children. Most children are infected with rotavirus, and the health and economic burdens of rotavirus gastroenteritis on healthcare systems and families are considerable. In 2012 pentavalent rotavirus vaccine (RV5) and diphtheria, tetanus, acellular pertussis and inactivated poliovirus vaccine derived from Sabin strains (DTaP-sIPV) were licensed in Japan. We examined the immunogenicity and safety of DTaP-sIPV when administrated concomitantly with RV5 in Japanese infants. A total of 192 infants 6 to 11 weeks of age randomized to Group 1 (N = 96) received DTaP-sIPV and RV5 concomitantly, and Group 2 (N = 96) received DTaP-sIPV and RV5 separately. Antibody titer to diphtheria toxin, pertussis antigens (PT and FHA), tetanus toxin, and poliovirus type 1, 2, and 3 were measured at 4 to 6 weeks following 3-doses of DTaP-sIPV. Seroprotection rates for all components of DTaP-sIPV were 100% in both groups, and the geometric mean titers for DTaP-sIPV in Group 1 were comparable to Group 2. Incidence of systemic AEs (including diarrhea, vomiting, fever, and nasopharyngitis) were lower in Group 1 than in Group 2. All vaccine-related AEs were mild or moderate in intensity. There were no vaccine-related serious AEs, no deaths, and no cases of intussusception during the study. Concomitant administration of DTaP-sIPV and RV5 induced satisfactory immune responses to DTaP-sIPV and acceptable safety profile. The administration of DTaP-sIPV given concomitantly with RV5 is expected to facilitate compliance with the vaccination schedule and improve vaccine coverage in Japanese infants.

Regional Variations in the Incidence of Rotavirus Hospitalization in Children Living in Defined Regions of Akita and Kyoto Prefectures, Japan

Variable incidence rates of rotavirus gastroenteritis hospitalizations have been reported in Japan. However, it is not known whether the observed regional differences were due to the real difference in the occurrence of severe disease or other causes. This study aimed to determine the incidence rates of rotavirus hospitalization among children aged <5 years in the Yuri district in Akita prefecture and the Nantan district in Kyoto prefecture between March 2012 and February 2013. During this period, rotavirus vaccine uptake rates were equally low in both regions. All specimens were evaluated using the standardized case definition, severity scores, and the same assays. There were 44 rotavirus cases (44%) among 101 acute gastroenteritis-related hospitalizations in the Yuri district with a catchment population of 3,853, and 18 rotavirus cases (47%) among 38 acute gastroenteritis-related hospitalizations in the Nantan district with a catchment population of 5,128. While the severity score at the time of the hospitalizations was 11 in both hospitals, the incidence rates in Akita and Kyoto were 11.7 (95% confidence interval [CI]: 8.5-15.6) and 3.9 (95% CI: 2.1-5.5) per 1,000 child-years, respectively. Thus, there was a real difference in the occurrence rate of severe rotavirus infections between the 2 regions.

Post-Marketing Benefit-Risk Assessment of Rotavirus Vaccination in Japan: A Simulation and Modelling Analysis

Introduction

Rotarix™, GSK’s live attenuated rotavirus vaccine, was introduced in Japan in 2011. A recent trend in reduction of rotavirus gastroenteritis (RVGE) due to this vaccine was described. However, an observed/expected analysis showed a temporal association with intussusception within 7 days post dose 1.

Objective

In this paper, we compare the benefit and risk of vaccination side-by-side in a benefit–risk analysis.

Methods

The number of vaccine-preventable RVGE-associated hospitalizations and deaths (benefit) and intussusception-associated hospitalizations and deaths (risk) following two doses of Rotarix™ in Japan was compared using simulations. Source data included peer-reviewed clinical and epidemiological publications, Japanese governmental statistics (Statistics Bureau, Ministry of Internal Affairs and Communications), and market survey data.

Results

For a birth cohort of 1 million vaccinated Japanese children followed for 5 years, the benefit–risk analysis suggested that the vaccine would prevent ~17,900 hospitalizations and ~6.3 deaths associated with RVGE. At the same time, vaccination would be associated with about ~50 intussusception hospitalizations and ~0.017 intussusception deaths. Therefore, for every intussusception hospitalization caused by vaccination and for one intussusception-associated death, 350 (95 % CI 69–2510) RVGE-associated hospitalizations and 366 (95 % CI 59–3271) RVGE-associated deaths are prevented, respectively, by vaccination.

Conclusions

The benefit–risk balance for Rotarix™ is favorable in Japan. From a public health perspective, the benefits in terms of prevented RVGE hospitalizations and deaths for the vaccinated population far exceed the estimated risks due to intussusception.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-015-0376-7) contains supplementary material, which is available to authorized users.

The Hidden Health and Economic Burden of Rotavirus Gastroenteritis in Malaysia: An Estimation Using Multiple Data Sources

BACKGROUND

Rotavirus gastroenteritis (RVGE) results in substantial mortality and morbidity worldwide. However, an accurate estimation of the health and economic burden of RVGE in Malaysia covering public, private and home treatment is lacking.

METHODS

Data from multiple sources were used to estimate diarrheal mortality and morbidity according to health service utilization. The proportion of this burden attributable to rotavirus was estimated from a community-based study and a meta-analysis we conducted of primary hospital-based studies. Rotavirus incidence was determined by multiplying acute gastroenteritis incidence with estimates of the proportion of gastroenteritis attributable to rotavirus. The economic burden of rotavirus disease was estimated from the health systems and societal perspective.

RESULTS

Annually, rotavirus results in 27 deaths, 31,000 hospitalizations, 41,000 outpatient visits and 145,000 episodes of home-treated gastroenteritis in Malaysia. We estimate an annual rotavirus incidence of 1 death per 100,000 children and 12 hospitalizations, 16 outpatient clinic visits and 57 home-treated episodes per 1000 children under-5 years. Annually, RVGE is estimated to cost US$ 34 million to the healthcare provider and US$ 50 million to society. Productivity loss contributes almost a third of costs to society. Publicly, privately and home-treated episodes consist of 52%, 27% and 21%, respectively, of the total societal costs.

CONCLUSIONS

RVGE represents a considerable health and economic burden in Malaysia. Much of the burden lies in privately or home-treated episodes and is poorly captured in previous studies. This study provides vital information for future evaluation of cost-effectiveness, which are necessary for policy-making regarding universal vaccination.

Estimating rotavirus vaccine effectiveness in Japan using a screening method

Rotavirus gastroenteritis is a highly contagious, acute viral disease that imposes a significant health burden worldwide. In Japan, rotavirus vaccines have been commercially available since 2011 for voluntary vaccination, but vaccine coverage and effectiveness have not been evaluated. In the absence of a vaccination registry in Japan, vaccination coverage in the general population was estimated according to the number of vaccines supplied by the manufacturer, the number of children who received financial support for vaccination, and the size of the target population. Patients with rotavirus gastroenteritis were identified by reviewing the medical records of all children who consulted 6 major hospitals in Saga Prefecture with gastroenteritis symptoms. Vaccination status among these patients was investigated by reviewing their medical records or interviewing their guardians by telephone. Vaccine effectiveness was determined using a screening method. Vaccination coverage increased with time, and it was 2-times higher in municipalities where the vaccination fee was supported. In the 2012/13 season, vaccination coverage in Saga Prefecture was 14.9% whereas the proportion of patients vaccinated was 5.1% among those with clinically diagnosed rotavirus gastroenteritis and 1.9% among those hospitalized for rotavirus gastroenteritis. Thus, vaccine effectiveness was estimated as 69.5% and 88.8%, respectively. This is the first study to evaluate rotavirus vaccination coverage and effectiveness in Japan since vaccination began.

Epidemiology of gastroenteritis viruses in Japan: Prevalence, seasonality, and outbreak

Acute gastroenteritis has been recognized as one of the most common diseases in humans and continues to be a major public health problem worldwide. Several groups of viruses have been reported as the causative agents of acute gastroenteritis, including rotavirus, norovirus, sapovirus, human astrovirus, adenovirus, and an increasing number of others which have been reported more recently. The epidemiology, prevalence, seasonality, and outbreaks of these viruses have been reviewed in a number of studies conducted in Japan over three decades. Rotavirus and norovirus were the two most common viruses detected almost equally in children under 5 years of age who were suffering from acute gastroenteritis. Like many other countries, the main rotavirus strains circulating in pediatric patients in Japan are G1P[8], G2P[4], G3P[8], and G9P[8]. Norovirus GII.4 was involved in most outbreaks in Japan and found to be associated with the emergence of new variants Sydney_2012. The classic human astrovirus, MLB, and VA clades astroviruses were also commonly found in pediatric patients with acute diarrhea. The sapovirus and adenovirus have been identified as the minor viral causative agents for acute gastroenteritis in Japan.

Active, population-based surveillance for rotavirus gastroenteritis in Chinese children: Beijing Municipality and Gansu Province, China

BACKGROUND

Estimates of population-based incidence for rotavirus inpatient and outpatient visits, as well as their associated medical costs, can provide valuable information to assess the potential benefits of rotavirus vaccination.

METHODS

We conducted active surveillance for rotavirus gastroenteritis at 6 medical institutions for children younger than 5 years from July 2012 to June 2013 in Beijing Municipality and Gansu Province. We collected stool samples of diarrhea patients for testing rotavirus, and epidemiological, clinical and cost data.

RESULTS

The proportion of rotavirus-positive for inpatient and outpatient visits from Beijing was 28.7% (138/481) and 19.4% (133/687); a statistically lower proportion than observed in Gansu among inpatient visits (45.2%, 245/542, P < 0.001) and among outpatient visits (28.8%, 66/229, P = 0.003), respectively. The G9P[8] genotype was most prevalent in Beijing (60.6%) and in Gansu (77.6%). The median Vesikari scale value was 16 for rotavirus inpatients and 15 for nonrotavirus inpatients. Population-based estimated rates of rotavirus-related hospitalizations were 14.4 (95% CI, 13-16) per 10,000 children, and the rate of rotavirus gastroenteritis in the outpatient setting was 149 (95% CI, 145-153) per 10,000 children younger than 5 years. The estimated total number of rotavirus-related inpatient visits were 3790 (95% CI, 2488-3827) cases and 29,101 (95% CI: 27,748-29,279) outpatient visits. The total cost of rotavirus infection was $1.4 million (95% CI, $0.9-1.4 million) for hospitalizations and $4.2 million (95% CI, $4.0-4.2 million) for outpatient visits per year in Beijing and Gansu.

CONCLUSION

Rotavirus is the most common cause of severe acute gastroenteritis (AGE) in children younger than 5 years worldwide,accounting for an estimated 25 million clinic visits, 2 million hospitalizations and 453,000 deaths each year. In China, the world's most populous nation, surveillance at sentinel hospitals showed that approximately 48% of AGE hospitalizations among children younger than 5 years were attributed to rotavirus from 2003 to 2007, and 13,387 rotavirus deaths were estimated in China in 2002 alone.The Lanzhou lamb rotavirus vaccine, consisting of serotype G10P[12], was licensed in 2000 but is not included in the National Expanded Program of Immunization vaccine recommendations for Chinese children. License applications for new rotavirus vaccines (Rotarix, produced by GlaxoSmithKline Biologicals, and RotaTeq, produced by Merck and Company) have been submitted for administering these vaccines to Chinese infants [corrected].

Acute nonbacterial gastroenteritis in hospitalized children: a cross sectional study

BACKGROUND

Viral acute gastroenteritis (AGE) is a major cause of morbidity in childhood and leads to hospitalization in developed countries, such as Iran.

OBJECTIVES

The aim of this study was to determine the prevalence and viral types (rotavirus, adenovirus, human parechoviruses-1, and human bocavirus) of acute nonbacterial gastroenteritis in hospitalized children.

PATIENTS AND MATERIALS

This was a across-sectional prospective study performed at the Pediatric Department of Rasoul Hospital, Tehran, Iran (2009-2011) on 80 hospitalized children with viral AGE. All Stool samples were collected on viral transport media. Human bocavirus (HBoV) was detected using the Real-time PCR TaqMan method. Molecular detection of human parechovirus type 1 (HPeV-1) RNA in stool samples was done using a specific nested reverse transcription PCR (RT-PCR). Rota and adeno virus antigens were sought by rapid chromatographic tests. P values less than 0.05 were considered statistically significant.

RESULTS

Fever was determined in 47.5% of cases (38), nausea and vomiting in 42.5% (34), respiratory symptoms in 16.3% (13), abdominal pain in 76%. Duration of diarrhea was 1-30 days (mean = 6.3 + 4.3 days). No dehydration was observed in 43.5% of subjects, mild dehydration in 33.8%, moderate dehydration in 17.5% and severe dehydration in 5% of cases. Positive rotavirus was found in 48.8% of cases (39), adenovirus in 20% (16), HBoV in 8% (6) and HPeV-1 in 23.2% (19), and adeno and rotaviruses co-infection in 6% (4). The frequency of positive HBoV was significantly lower than adeno and rotaviruses infection (P value = 0.0001). Rotavirus was more frequent in males (P value = 0.003) and in young children (17.49 months vs. 21.44 months) [P value = 0.03, CI = -13.4, 5.5]. Rotavirus infection was related to the degree of dehydration (P value = 0.001) but was not related to the presence of vomiting or fever (P value > 0.5).

CONCLUSIONS

This study indicates that viral agents, especially rotavirus (48.8%), HPeV-1 (23.2%) and adenovirus (20%) are the most important causes for viral AGE in children while HBoV (8%) is infrequent during childhood. Determination of various viral pathogens of AGE is very important in planning diarrhea disease control strategies in our country where rotavirus vaccination in not routinely used.

The burden of rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis among children aged less than 6 years in Japan: a retrospective, multicenter epidemiological survey

Background

Rotavirus is a leading worldwide cause of acute gastroenteritis in young children. This retrospective hospital-based study assessed the burden of rotavirus gastroenteritis in children younger than 6 years in Japan.

Methods

Children admitted to eight hospitals for acute gastroenteritis between 2008 and 2009 were identified from hospital admission databases. Diagnosis of acute gastroenteritis/rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis was confirmed based on either the International Classification of Diseases and Related Health Problems 10th revision (ICD10) codes (intestinal infectious diseases [AA00-AA09] and rotavirus gastroenteritis [A08.0]) or from rapid rotavirus diagnostic test results.

Results

Of 13,767 hospitalized children, 11.9% (1,644), 4.8% (665) and 0.6% (81) were diagnosed with acute gastroenteritis, rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis, respectively. Among acute gastroenteritis hospitalizations, 40.5% (665/1,644; ICD10 and rapid test) and 57.7% (645/1,118; rapid test only) were confirmed as rotavirus positive. Of 1,563 children with community-acquired acute gastroenteritis, 584 (37.4%) cases were confirmed as rotavirus positive. The median durations of hospitalization for all and community-acquired rotavirus gastroenteritis were 5.0 days (range: 2.0−133.0 days) and 5.0 days (range: 2.0-34.0 days), respectively. Among rotavirus gastroenteritis hospitalizations, 12.2% (81/665) of cases were hospital-acquired and the median duration of hospitalization was 10.0 days (range: 2.0-133.0 days). The median duration of additional hospitalization due to hospital-acquired rotavirus gastroenteritis was 3.0 days (range: 0–14 days). The overall incidence rate of hospital-acquired rotavirus gastroenteritis was 1.0 per 1,000 children hospital-days. The number of rotavirus gastroenteritis cases peaked between February and May in both 2008 and 2009, and the highest number of cases was reported in March 2008 (21.8%; 145/665). The highest number of rotavirus gastroenteritis hospitalizations (24.1%; 160/665) was observed in children aged 12–18 months. The proportion of hospital-acquired rotavirus gastroenteritis was higher in children aged below 18 months as compared to children at least 18 months of age (0.94 [95% CI: 0.71-1.21] vs. 0.39 [95% CI: 0.25-0.58]) and for children hospitalized for at least 5 days compared to those hospitalized for less than 5 days (0.91 [95% CI: 0.72-1.14] vs. 0.15 [95% CI: 0.05-0.32]).

Conclusions

Both community- and hospital-acquired rotavirus gastroenteritis are significant public health problems in Japan. Data from this study justify the need for the introduction and implementation of rotavirus vaccination in the Japanese national immunization program.

Trial registration

ClinicalTrials.gov, NCT01202201

Burden of rotavirus gastroenteritis and distribution of rotavirus strains in Asia: a systematic review

BACKGROUND

Rotavirus is the leading cause of severe diarrhea in children worldwide. We systematically reviewed the burden of rotavirus gastroenteritis (RVGE) and distribution of rotavirus strains in Asia.

METHODS

We searched MEDLINE, EMBASE and the World Health Organization (WHO) website for the term "rotavirus" and the name of each country. We included studies that were conducted in children between 2000 and 2011 and that examined the epidemiology, health and/or economic burden of RVGE, and G and P-type distribution in Eastern, South East, Southern and Central Asia. Random effects models were used to pool the proportions of RVGE. We also estimated child mortality due to RVGE using the updated WHO and United Nations Children's Fund's mortality estimates in 2008.

RESULTS

The search identified 113 eligible articles. The incidence rates of rotavirus-related hospitalizations in children under 5 years of age ranged from 2.1 to 20.0 cases per 1000 children per year with the highest rates reported in Bangladesh, South Korea, Taiwan, Thailand, and Vietnam. Rotavirus accounted for 37.5% of year-round hospitalized gastroenteritis cases, with higher proportions reported in South East Asia. Rotavirus was associated with approximately 145,000 deaths every year in Asia, with the greatest numbers occurring in India, Pakistan, and Indonesia. The highest annual societal costs of treating RVGE were reported in China (US$365 million), followed by Japan (US$254 million) and India (US$41-72 million). A diversity of rotavirus G and P-types was observed across Asia and the distribution of strains differed by country and year. The most common strains were G1P[8] (23.6%), G2P[4] (11.8%), G3P[8] (18.9%), and G9P[8] (7.4%).

CONCLUSIONS

Rotavirus is associated with substantial hospitalizations and deaths among children and causes large healthcare expenditures throughout Asia. Safe and effective rotavirus vaccines could substantially reduce the burden of disease.

Rotarix in Japan: Expectations and Concerns

A live-attenuated, orally-administered, monovalent, human rotavirus vaccine, Rotarix® (GlaxoSmithKline Biologicals, Rixensart, Belgium), was licensed and launched in 2011 as the first rotavirus vaccine in Japan. The rotavirus causes a substantial disease burden with an estimated 790,000 outpatient visits, 27,000–78,000 hospitalizations, and approximately 10 deaths each year in Japan. Since a recent clinical trial showed that Rotarix was as efficacious in Japan as in other industrialized countries, it is expected that the annual number of rotavirus hospitalizations will be reduced to between 1000–3000, and that outpatient visits will be reduced to 200,000. The universal rotavirus immunization program with Rotarix was calculated to be at the threshold of being cost-effective, even from the healthcare perspective, and it was highly cost-effective from the societal perspective, assuming that Rotarix is co-administered with other childhood vaccines. While Rotarix contains only a single G1P[8] human rotavirus, the postlicensure studies in Brazil showed that Rotarix provided a 75%–85% protective efficacy against severe dehydrating diarrhea or hospitalizations due to fully-heterotypic G2P[4] strains. While postlicensure studies detected a small and finite risk of intussusception associated with the administration of Rotarix, the authors conclude that Rotarix is safe to administer to infants between 6-12 weeks of age for the first dose and by 24 weeks of age for the second dose. However, the authors strongly discourage the delayed administration of the first dose between 13-20 weeks of age, which is allowed without any warning. Given the high incidence of naturally-occurring intussusception in Japan (185 cases per 100,000 children/year among children less than 1 year of age), this should prevent pediatricians and parents from having ill-perceptions of Rotarix being associated with an increased number of temporally-associated intussusception, and fully appreciate the benefit of the rotavirus vaccine.