Rotavirus genotype and Vesikari score of outpatients in Japan in the vaccine era

Development and Evaluation of a New Gastroenteritis Clinical Severity Score for Children Aged Under 5

AIM

To develop and internally validate a new severity score to more accurately assess the clinical severity forms of acute gastroenteritis (AGE) in children from birth to age 5 years.

METHODS

We included children consulting for AGE in the emergency department of the University Hospital of Nantes (March 2017-June 2019). We developed and evaluated a new predictive score (GASTROVIM score) using the classification and regression trees. We compared its diagnostic performance with the two existing scores: the Vesikari score and clinical dehydration scale (CDS). A clinical expert a posteriori evaluated children's medical records to determine the severity form of AGE as the gold standard.

RESULTS

Of the 200 children included, 129 (64.5%) had severe forms of AGE according to the GASTROVIM score (maximal number of liquid stools and vomiting per day, weight loss and CDS), with sensitivity 90.0% (95% CI: 83.5-94.6) and specificity 82.9% (72.0-90.8). The Vesikari score had similar sensitivity (97.3%) but lower specificity (17.0%) and the CDS had lower sensitivity (28.3%) and higher specificity (100%) than the GASTROVIM score.

CONCLUSION

The GASTROVIM score could discriminate severe forms of AGE with good diagnostic performance. Nevertheless, external validation in other populations and/or other countries is needed.

The Application of the Vesikari and Modified Vesikari Severity Scores in Complicated Pediatric Gastroenteritis of Viral Origin: An Observational Study

Background/Objectives: Viral gastroenteritis can have a potentially fatal outcome at young ages and the recognition of severe cases could be aided by clinically derived severity scores. Methods: This observational study intended to conduct a comparative assessment of the utility of the Vesikari and modified Vesikari score in the evaluation of viral gastroenteritis severity and for the possible prediction of the dehydration degree. A total number of 113 children diagnosed with gastroenteritis were retrospectively enrolled and divided based on viral etiology into group 1 (34 children with unknown viral etiology), group 2 (60 children with rotavirus) and group 3 (19 children with adenovirus). Results: The highest mean Vesikari and modified Vesikari scores were found in group 2 (p < 0.01; p = 0.01). A significant increase in liver enzymes was also identified in patients infected with rotavirus. The highest mean diarrhea, vomiting duration and body temperature were found in group 3 (p < 0.01; p < 0.01; p = 0.02), as well as the highest mean inflammatory markers, such as C-reactive protein (CRP; p = 0.01) and the erythrocyte sedimentation rate (p < 0.01). Significant linear associations were found between pH, bicarbonate level, base excess and the Vesikari scores, whereas urea, CRP and aspartate aminotransferase levels were associated with both severity scores. ROC curve analysis revealed a significant correlation between the Vesikari scores and dehydration degree (p < 0.01), with numeric cut-off values of 11.5 being proposed for the differentiation between mild and moderate gastroenteritis and 13.5 for the distinction between moderate and severe gastroenteritis. Conclusions: Both severity scores are useful in clinical settings, but more studies enrolling populations with various enteral infections could provide more insight into their etiology-based performance and reflection of paraclinical changes.

Changes in vaccine coverage and incidence of acute gastroenteritis and severe rotavirus gastroenteritis in children <5 years in Shibata City, Niigata Prefecture, Japan

Rotavirus (RV) vaccines were first introduced in 2011 and adopted for universal vaccination in 2020 in Japan. However, the effectiveness of RV vaccines after being adopted for universal vaccination in 2020 has not been reported. Because of the easy accessibility of clinics in Japan, many children are not usually hospitalized for RV gastroenteritis (RVGE). Therefore, in order to evaluate the impact of the RV vaccine since 2008, we investigated the incidence of hospitalization for RVGE as well as the frequency of children aged < 5 years who received medical treatment for severe RVGE at clinics in Shibata City, Japan. The RV vaccine coverage rate was 94.0% (1,046/1,113) in Shibata City after universal vaccination in 2020; this was a significant increase from previous rates. The incidence per 1000 person - years for RVGE hospitalization and severe RVGE at clinics were significantly higher among children aged < 3 years than in previous time periods. The incidence in children with all acute gastroenteritis (AGE) decreased significantly after universal vaccination during the COVID-19 pandemic. The proportion of severe RVGE among all AGE cases also decreased significantly after universal vaccination among children aged < 3 years (0.0%) and those aged 3-4 years (0.6%). There were significant differences in the distribution of RV genotypes isolated from the feces of children with RVGE between different eras divided by RV vaccination rates, especially G1P[8], which was the major genotype before it recently almost disappeared. Further studies are warranted to assess the impact of the COVID-19 pandemic.

Review of the past and present status of respiratory syncytial virus and rotavirus infections that commonly affect children

Respiratory syncytial virus (RSV) and rotavirus infections are long-standing infectious diseases that affect children worldwide. RSV and rotavirus were first discovered in clinical specimens in 1955 and 1973, respectively. From their discovery to the present day, significant progress has been made in understanding these two infections. The introduction of a simple and rapid antigen diagnostic test into clinical settings in the 1990s offered new insight into the clinical characteristics and epidemiology of these infections. Regarding therapeutics, symptomatic treatments have remained the mainstay; however, prophylactic humanized anti-RSV monoclonal antibodies have been developed and advances in structural biology may allow for more effective human anti-RSV monoclonal antibodies and novel RSV vaccines to be developed soon. For rotavirus, two vaccines have been licensed and broadly applied over the past 10 years, which have been successful clinically and have changed the epidemiology of rotavirus infections in Japan.

Whole genome sequencing and genomic characterization of a DS-1-like G2P[4] group A rotavirus in Japan

After rotavirus was discovered in 1973, it became the leading pathogen in causing acute gastroenteritis in humans worldwide. In this study, we performed whole genome sequencing and genomic characterization of a DS-1-like G2P[4] group A rotavirus in feces of a Japanese child with acute gastroenteritis who was fully Rotarix® vaccinated. The genomic investigation determined a genomic constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 of this rotavirus strain. Its antigenic epitopes of the VP7 and VP4 proteins had significant mismatches compared with the vaccine strains. Our study is the latest attempt to investigate the evolution of the VP7 and VP4 genes of emerging G2P[4] rotavirus in Japan.

Vaccine evaluation and genotype characterization in children infected with rotavirus in Qatar

BACKGROUND

We characterized and identified the genetic and antigenic variations of circulating rotavirus strains in comparison to used rotavirus vaccines.

METHODS

Rotavirus-positive samples (n = 231) were collected and analyzed. The VP7 and VP4 genes were sequenced and analyzed against the rotavirus vaccine strains. Antigenic variations were illustrated on the three-dimensional models of surface proteins.

RESULTS

In all, 59.7% of the hospitalized children were vaccinated, of which only 57.2% received two doses. There were no significant differences between the vaccinated and non-vaccinated groups in terms of clinical outcome. The G3 was the dominant genotype (40%) regardless of vaccination status. Several amino acid changes were identified in the VP7 and VP4 antigenic epitopes compared to the licensed vaccines. The highest variability was seen in the G3 (6 substitutions) and P[4] (11 substitutions) genotypes in comparison to RotaTeq®. In comparison to Rotarix®, G1 strains possessed three amino acid changes in 7-1a and 7-2 epitopes while P[8] strains possessed five amino acid changes in 8-1 and 8-3 epitopes.

CONCLUSIONS

The current use of Rotarix® vaccine might not be effective in preventing the infection due to the higher numbers of G3-associated cases. The wide range of mutations in the antigenic epitopes compared to vaccine strains may compromise the vaccine's effectiveness.

IMPACT

The reduced rotavirus vaccine effectiveness necessitate regular evaluation of the vaccine content to ensure optimal protection. We characterized and identified the genetic and antigenic variations of circulating rotavirus strains in comparison to the Rotarix vaccine strain that is used in Qatar. The study highlight the importance for regular monitoring of emerging rotavirus variants and their impact on vaccine effectiveness in young children.

Changing distribution of rotavirus A genotypes circulating in Japanese children with acute gastroenteritis in outpatient clinic, 2014-2020

BACKGROUND

Rotavirus A (RVA) is a major cause of severe acute gastroenteritis (AGE) in infants and children worldwide. In Japan, two kinds of rotavirus vaccines have been introduced as voluntary vaccines in 2011 and 2012, respectively, and launched into the national vaccine program in October 2020.

METHODS

In this study, we investigated prevalence of RVA and their molecular characterization in the stool samples collected from infants and children with AGE who visited one outpatient clinic in Japan, from July 2014 to June 2020, during voluntary vaccination with two kinds of rotavirus vaccines.

RESULTS

The RVA detection rates decreased from 44.7 % in 2014-2015 to 35.4 % in 2018-2019, whereas in 2019-2020 the numbers of samples collected were dramatically decreased and none of RVA was detected. During this study period, rotavirus vaccination rates in this area increased from 32.4 % to 62.2 %. Distribution of RVA VP7 (G), VP4 (P), and VP6 (I) genotypes in this area had changed year by year; the major genotype combinations were G1P[8]I1 and G1P[8]I2 in 2014-2015, G2P[4]I2 and G9P[8]I1 in 2015-2016, G1P[8]I1 and G8P[8]I2 in 2017-2018, and G8P[8]I2 in 2018-2019. Phylogenetic analysis demonstrated that VP7 nucleotide sequences of G1 were genetically diverse compared with those of other G genotypes in this study. Meanwhile, predominance of unusual G2P[8]I1, G2P[8]I2 and mixed P genotypes were observed only in 2016-2017, but did not carry on in 2017-2019. The equine-like G3 was detected only in 2016-2017.

CONCLUSIONS

The results revealed diversity of RVA genotypes and the genotype combinations have changed year by year in Japan, during the study period of 2016-2020.

Changes and remaining challenges for the Japanese immunization program: Closing the vaccine gap

The Japanese immunization program has made considerable progress since 2009: several new vaccines have been introduced and most are included in the National Immunization Program (NIP). In October 2020, the Japanese law on immunization was revised, which resulted in a few laudable achievements. First, rotavirus vaccines were added to the NIP, 10 years after their introduction, and noteworthy studies of vaccine effectiveness and the incidence of intussusception in Japanese children were published. Second, rules on vaccine intervals-which had been a longstanding concern-were withdrawn. In addition to this revision of the law, the Japanese version of the Vaccine Information Statement (VIS) was released by the Japan Pediatric Society in 2018. The VIS provides useful caregiver information on general immunization concepts and individual vaccines. Further challenges for the Japanese immunization program include (1) administering a booster dose of pertussis-containing vaccine to preschool children or teenagers, (2) reestablishing the active recommendation for human papilloma virus vaccines, (3) adding the mumps and influenza vaccines to the NIP, and (4) ensuring optimal dosing of seasonal influenza vaccines. During the current coronavirus disease 2019 (COVID-19) pandemic, vaccination rates among children have been decreasing in many countries. In Japan, vaccination rates have been stable in infants, but declining among toddlers and school-aged children, despite public awareness of the need for timely administration of vaccines during the pandemic. Clearly, further action is needed if we are to adequately protect children living in Japan from vaccine-preventable diseases.

Rotavirus vaccination in Japan: Efficacy and safety of vaccines, changes in genotype, and surveillance efforts

In Japan, a monovalent rotavirus vaccine (RV1) and a pentavalent rotavirus vaccine (RV5) were launched as voluntary vaccinations in November 2011 and July 2012, respectively. Rotavirus (RV) vaccine coverage in Japan increased from 30.0% in 2012 to 78.4% in 2019. The number of RV gastroenteritis hospitalizations decreased after 2014 in Japan, and is expected to decrease further following the introduction of RV vaccines into the national immunization program in October 2020. The incidence rates of intussusception (IS) among children aged <1 year were 102.8 and 94.0 per 100,000 person-years in the pre-vaccine (2007-2011) and post-vaccine (2012-September 2014) eras, respectively. IS incidence did not increase following RV vaccine introduction in Japan. The efficacy and safety of RV vaccination were both documented in Japan. To reduce the risk of IS following RV vaccination, it is important that children receive a first dose of RV vaccine at age <15 weeks, preferably at age 2 months. Some strains that have emerged since RV vaccine introduction, such as DS-1-like G1P[8], eG3, and G8P[8], have spread nationwide. These three emerging genotypes did not affect the severity of the RV infection. Continuous city-level surveillance, using analysis of all 11 RV genome segments, is necessary to elucidate the genetic characteristics of prevalent RV strains. These efforts would also clarify the influence of vaccination on genetic changes of RV strains and the emergence of new genotypes.

Molecular and clinical characterization of the equine-like G3 rotavirus that caused the first outbreak in Japan, 2016

Since 2013, equine-like G3 rotavirus (eG3) strains have been detected throughout the world, including in Japan, and the strains were found to be dominant in some countries. In 2016, the first eG3 outbreak in Japan occurred in Tomakomai, Hokkaido prefecture, and the strains became dominant in other Hokkaido areas the following year. There were no significant differences in the clinical characteristics of eG3 and non-eG3 rotavirus infections. The eG3 strains detected in Hokkaido across 2 years from 2016 to 2017 had DS-1-like constellations (i.e. G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2), and the genes were highly conserved (97.5-100 %). One strain, designated as To16-12 was selected as the representative strain for these strains, and all 11 genes of this strain (To16-12) exhibited the closest identity to one foreign eG3 strain (STM050) seen in Indonesia in 2015 and two eG3 strains (IS1090 and MI1125) in another Japanese prefecture in 2016, suggesting that this strain might be introduced into Japan from Indonesia. Sequence analyses of VP7 genes from animal and human G3 strains found worldwide did not identify any with close identity (>92 %) to eG3 strains, including equine RV Erv105. Analysis of another ten genes indicated that the eG3 strain had low similarity to G2P[4] strains, which are considered traditional DS-1-like strains, but high similarity to DS-1-like G1P[8] strains, which first appeared in Asia in 2012. These data suggest that eG3 strains were recently generated in Asia as mono-reassortant strain between DS-1-like G1P[8] strains and unspecified animal G3 strains. Our results indicate that rotavirus surveillance in the postvaccine era requires whole-genome analyses.

Severe rotavirus gastroenteritis in children older than 5 years after vaccine introduction

INTRODUCTION

Rotavirus (RV) is the major pathogen responsible for acute gastroenteritis in infants. Since RV vaccines were introduced, a substantial decline in the incidence of severe RV infection has been reported. However, some burden still exists, even in developed countries, including Japan.

METHODS

We retrospectively surveyed 380 patients hospitalized for acute gastroenteritis from 2015 to 2019. In 2019, additional detailed clinical information of 21 patients with RV gastroenteritis was obtained to evaluate the efficacy of the RV vaccine. Nine fecal samples from those patients were collected to detect the RV genotypes.

RESULTS

Our data showed an increasing trend in hospitalizations for severe RV gastroenteritis in children older than 5 years. According to the Vesikari clinical severity scores in the older group (≥5 years), the gastrointestinal symptoms in vaccinated patients were less severe than those in unvaccinated patients (p = 0.014). The genotype analysis revealed that G9P[8]I1 was the major genotype in the recruited patients in 2019.

CONCLUSIONS

This report warns that children older than 5 years could be affected by severe RV infection and suggests prompt intervention for this age group, similar to that in infants. In the new period in which the RV vaccine is included in Japanese national immunization programs beginning October 2020, continuous monitoring of patient clinical characteristics and RV epidemiology is required to determine the role of vaccines.

High prevalence of DS-1-like rotavirus infection in Thai adults between 2016 and 2019

Rotavirus infection is the most common cause of viral diarrhea in infants and young children but uncommon and usually asymptomatic in adults. In the winter of 2017-2018, a large-scale outbreak of rotavirus in both children and adults was reported in Thailand. The current study focused on the prevalence, genotyping, and molecular characterization of rotavirus infections in Thai adults from July 2016 to December 2019. In 2,598 stool samples collected from adult residents of Bangkok (aged #x2265; 15 years) with acute gastroenteritis, rotavirus was detected via real-time RT-PCR analysis of the VP6 gene. G, P and I genotypes were determined by direct sequencing of VP7, VP4, and VP6 genes, respectively. Our results showed 8.7% (226/2,598) of stool samples were positive for rotavirus. The incidence of rotavirus was high during the winter season of 2017-2018 (17.7%) compared to another studied periods (4.5% between July 2016- October 2017 and 2.8% between March 2018- December 2019). Nucleotide sequencing of VP7 and VP4 revealed G3P[8] as the predominant strain (33.2%,75/226), followed by G9P[8] (17.3%,39/226), and G2P[4] (15.0%,34/226). Uncommon G and P combinations were additionally detected at low frequencies. VP6 sequencing was conducted to discriminate I genotype between the Wa and DS-1 genogroup. The unusual DS-1-like G3P[8] strain was most prevalent amomg rotavirus strains detected in this study (29.6%, 67/226), and the corresponding VP7 sequences showed high nucleotide identity with unusual DS-1-like globally circulating strains. Our study demonstrates that rotavirus outbreaks in adults are attributable not only to high prevalence of RV infection but also the unusual DS-like genogroup. The collective findings reinforce the importance of investigating rotavirus diagnosis in adults suffering from acute gastroenteritis and taking appropriate preventive measures.