Surveillance of Human Rotaviruses in Wuhan, China (2019-2022): Whole-Genome Analysis of Emerging DS-1-like G8P[8] Rotavirus.

Group A rotaviruses (RVAs) are major etiologic agents of gastroenteritis in infants and young children worldwide. To study the prevalence and genetic characteristics of RVAs, a hospital-based surveillance study was conducted in Wuhan, China from June 2019 through May 2022. The detection rates of RVAs were 19.40% (142/732) and 3.51% (8/228) in children and adults, respectively. G9P[8] was the predominant genotype, followed by G8P[8] and G3P[8]. G8P[8] emerged and was dominant in the 2021-2022 epidemic season. The genome constellation of six G8P[8] strains was assigned to G8-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Phylogenetic analysis revealed that the VP7, VP4, VP2, VP3, NSP1, NSP2, NSP3, and NSP5 genes of these G8P[8] strains clustered closely with those of the G8P[8] strains in Asia and were distant from those of the P[8] and G2P[4] strains simultaneously detected in Wuhan. In contrast, the VP1, VP6, and NSP4 genes were closely related to the typical G2P[4] rotavirus, including those of G2P[4] strains simultaneously detected in Wuhan. The detection rate of RVAs decreased in the COVID-19 pandemic era. It was deduced that the G8P[8] rotaviruses that emerged in China may be reassortants, carrying the VP6, VP1, and NSP4 genes derived from the G2P[4] rotavirus in the backbone of the neighboring DS-1-like G8P[8] strains represented by CAU17L-103.

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.

Genomic epidemiology of the rotavirus G2P[4] strains in coastal Kenya pre- and post-rotavirus vaccine introduction, 2012-8.

The introduction of rotavirus vaccines into the national immunization programme in many countries has led to a decline in childhood diarrhoea disease burden. Coincidentally, the incidence of some rotavirus group A (RVA) genotypes has increased, which may result from non-vaccine-type replacement. Here, we investigate the evolutionary genomics of rotavirus G2P[4] which has shown an increase in countries that introduced the monovalent Rotarix® vaccine. We examined sixty-three RVA G2P[4] strains sampled from children (aged below 13 years) admitted to Kilifi County Hospital, coastal Kenya, pre- (2012 to June 2014) and post-(July 2014 to 2018) rotavirus vaccine introduction. All the sixty-three genome sequences showed a typical DS-1-like genome constellation (G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2). Pre-vaccine G2 sequences predominantly classified as sub-lineage IVa-3 and co-circulated with low numbers of sub-lineage IVa-1 strains, whereas post-vaccine G2 sequences mainly classified into sub-lineage IVa-3. In addition, in the pre-vaccine period, P[4] sub-lineage IVa strains co-circulated with low numbers of P[4] lineage II strains, but P[4] sub-lineage IVa strains predominated in the post-vaccine period. On the global phylogeny, the Kenyan pre- and post-vaccine G2P[4] strains clustered separately, suggesting that different virus populations circulated in the two periods. However, the strains from both periods exhibited conserved amino acid changes in the known antigenic epitopes, suggesting that replacement of the predominant G2P[4] cluster was unlikely a result of immune escape. Our findings demonstrate that the pre- and post-vaccine G2P[4] strains circulating in Kilifi, coastal Kenya, differed genetically but likely were antigenically similar. This information informs the discussion on the consequences of rotavirus vaccination on rotavirus diversity.

Genomic Analysis of G2P[4] Group A Rotaviruses in Zambia Reveals Positive Selection in Amino Acid Site 7 of Viral Protein 3.

The G2P[4] genotype is among the rotavirus strains that circulate commonly in humans. Several countries have reported its immediate upsurge after the introduction of rotavirus vaccination, raising concern about sub-optimal vaccine effectiveness against this genotype in the long term. This study aimed to gain insight into the evolution of post-vaccine Zambian G2P[4] group A rotavirus (RVA) strains and their overall genetic make-up by analysis of sequence alignments at the amino acid (AA) level. Twenty-nine Zambian G2P[4] rotavirus strains were subjected to whole-genome sequencing using the Illumina MiSeq® platform. All the strains exhibited the typical DS-1-like genotype constellation, and the nucleotide sequences of the 11 genome segments showed high nucleotide similarities (>97%). Phylogenetic analyses together with representative global G2P[4] RVA showed that Zambian strains clustered into human lineages IV (for VP2, VP4, VP7, NSP1, and NSP5), V (for VP1, VP3, VP6, NSP2, and NSP3), and XXIII (for NSP4). The AA differences between the lineages where the study strains clustered and lineages of global reference strains were identified and analyzed. Selection pressure analysis revealed that AA site seven in the Viral Protein 3 (VP3) genome segment was under positive selection. This site occurs in the region of intrinsic disorder in the VP3 protein, and Zambian G2P[4] strains could potentially be utilizing this intrinsically disordered region to survive immune pressure. The Zambian G2P[4] strains from 2012 to 2016 comprised the G2P[4] strains that have been circulating globally since the early 2000s, highlighting the epidemiological fitness of these contemporary G2P[4] strains. Continuous whole-genome surveillance of G2P[4] strains remains imperative to understand their evolution during the post-vaccination period.

Evolutionary changes between pre- and post-vaccine South African group A G2P[4] rotavirus strains, 2003-2017.

The transient upsurge of G2P[4] group A rotavirus (RVA) after Rotarix vaccine introduction in several countries has been a matter of concern. To gain insight into the diversity and evolution of G2P[4] strains in South Africa pre- and post-RVA vaccination introduction, whole-genome sequencing was performed for RVA positive faecal specimens collected between 2003 and 2017 and samples previously sequenced were obtained from GenBank (n=103; 56 pre- and 47 post-vaccine). Pre-vaccine G2 sequences predominantly clustered within sub-lineage IVa-1. In contrast, post-vaccine G2 sequences clustered mainly within sub-lineage IVa-3, whereby a radical amino acid (AA) substitution, S15F, was observed between the two sub-lineages. Pre-vaccine P[4] sequences predominantly segregated within sub-lineage IVa while post-vaccine sequences clustered mostly within sub-lineage IVb, with a radical AA substitution R162G. Both S15F and R162G occurred outside recognised antigenic sites. The AA residue at position 15 is found within the signal sequence domain of Viral Protein 7 (VP7) involved in translocation of VP7 into endoplasmic reticulum during infection process. The 162 AA residue lies within the hemagglutination domain of Viral Protein 4 (VP4) engaged in interaction with sialic acid-containing structure during attachment to the target cell. Free energy change analysis on VP7 indicated accumulation of stable point mutations in both antigenic and non-antigenic regions. The segregation of South African G2P[4] strains into pre- and post-vaccination sub-lineages is likely due to erstwhile hypothesized stepwise lineage/sub-lineage evolution of G2P[4] strains rather than RVA vaccine introduction. Our findings reinforce the need for continuous whole-genome RVA surveillance and investigation of contribution of AA substitutions in understanding the dynamic G2P[4] epidemiology.

Characterisation of a G2P[4] Rotavirus Outbreak in Western Australia, Predominantly Impacting Aboriginal Children.

In May, 2017, an outbreak of rotavirus gastroenteritis was reported that predominantly impacted Aboriginal children ≤4 years of age in the Kimberley region of Western Australia. G2P[4] was identified as the dominant genotype circulating during this period and polyacrylamide gel electrophoresis revealed the majority of samples exhibited a conserved electropherotype. Full genome sequencing was performed on representative samples that exhibited the archetypal DS-1-like genome constellation: G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 and phylogenetic analysis revealed all genes of the outbreak samples were closely related to contemporary Japanese G2P[4] samples. The outbreak samples consistently fell within conserved sub-clades comprised of Hungarian and Australian G2P[4] samples from 2010. The 2017 outbreak variant was not closely related to G2P[4] variants associated with prior outbreaks in Aboriginal communities in the Northern Territory. When compared to the G2 component of the RotaTeq vaccine, the outbreak variant exhibited mutations in known antigenic regions; however, these mutations are frequently observed in contemporary G2P[4] strains. Despite the level of vaccine coverage achieved in Australia, outbreaks continue to occur in vaccinated populations, which pose challenges to regional areas and remote communities. Continued surveillance and characterisation of emerging variants are imperative to ensure the ongoing success of the rotavirus vaccination program in Australia.

Rotavirus outbreak among adults in a university hospital in Germany.

BACKGROUND: Rotaviruses are the main cause of acute viral gastroenteritis in children under five years of age. Adults seem to be less frequently affected by rotaviruses most likely due to partial immunity resulting from prior infections. OBJECTIVES: To describe a hospital-associated outbreak of rotavirus infections among adults. STUDY DESIGN: Routine diagnostics and contact screening of symptomatic patients hospitalized at the university hospital of Freiburg. For rotavirus-positive patients, we performed rotavirus genotyping of all rotavirus RT-PCR positive samples and phylogenetic analysis. RESULTS: Between December 2016 and April 2017 routine diagnostics showed an unexpectedly high number of rotavirus infections among adults with the exception of one pediatric case. In total, 32 temporal-associated cases were identified. Among these, two asymptomatic cases were detected. Genotyping showed that all isolates belonged to rotavirus G2P[4]. Phylogenetic analysis confirmed an outbreak. Infection prevention and control successfully contained further spread. CONCLUSIONS: Infections with rotavirus are rare among adults but may spread between patients making timely recognition of rotavirus infections important for infection control. Rapid phylogenetic analysis is crucial for proactive infection control.

Dynamics of G2P[4] strain evolution and rotavirus vaccination: A review of evidence for Rotarix.

Rotavirus (RV) gastroenteritis is a vaccine-preventable disease that creates high medical and economic burden in both developed and developing countries. Worldwide, more than 100 countries have introduced RV vaccines in their national immunization programs, and the remarkable impact of reducing the burden of severe childhood gastroenteritis has been unequivocally demonstrated. Currently, 2 oral vaccines (Rotarix, GSK and RotaTeq, Merck) are widely utilized. Recent temporary increases in the relative prevalence of G2P[4] RV strains have been observed in countries implementing RV vaccination. This comprehensive literature review aims to provide an insight on RV genotype evolution in the context of mass vaccination with Rotarix, particularly in the case of G2P[4]. In the post-vaccine era, strain surveillance data indicated temporal and spatial changes in countries both with and without RV vaccination programs. Annual fluctuations in G2P[4] prevalence seem to occur naturally, with no substantial differences between countries using Rotarix, RotaTeq or mixed vaccination programs. Moreover, Rotarix has been shown to be efficacious and effective against gastroenteritis caused by non-vaccine strains, including G2P[4]. These data indicate that shifts in RV genotype distribution are likely to constitute an inherent process of virus evolution to infect the human gut. Following RV vaccine introduction, incidences of RV gastroenteritis declined dramatically and mass vaccination will likely maintain this status, despite possible fluctuations in the relative distribution of genotypes. There is no conclusive evidence of unusual burst of new or vaccine-escape strains since global RV vaccines use. The emergence of strains with a potential to increase the current burden of RV disease should be continuously monitored and can only be established by exhaustive characterization of strains, including whole genomic sequencing. Given the natural fluctuations in RV strains over time, caution is advised when interpreting temporal changes in RV strain dynamics, as they could mistakenly be attributed to vaccination.

Australian Rotavirus Surveillance Program: Annual Report, 2017

This report, from the Australian Rotavirus Surveillance Program and collaborating laboratories Australia-wide, describes the rotavirus genotypes identified in children and adults with acute gastroenteritis during the period 1 January to 31 December 2017. During this period, 2,285 faecal specimens were referred for rotavirus G and P genotype analysis, including 1,103 samples that were confirmed as rotavirus positive. Of these, 1,014/1,103 were wildtype rotavirus strains and 89/1,103 were identified as rotavirus vaccine-like. Genotype analysis of the 1,014 wildtype rotavirus samples from both children and adults demonstrated that G2P[4] was the dominant genotype nationally, identified in 39% of samples, followed by equine-like G3P[8] and G8P[8] (25% and 16% respectively). Multiple outbreaks were recorded across Australia, including G2P[4] (Northern Territory, Western Australia, and South Australia), equine-like G3P[8] (New South Wales), and G8P[8] (New South Wales and Victoria). This year also marks the change in the Australian National Immunisation Program to the use of Rotarix exclusively, on 1 July 2017.

Genomic constellation and evolution of Ghanaian G2P[4] rotavirus strains from a global perspective.

Understanding of the genetic diversity and evolution of Rotavirus A (RVA) strains, a common cause of severe diarrhoea in children, needs to be based on the analysis at the whole genome level in the vaccine era. This study sequenced the whole genomes of six representative G2P[4] strains detected in Ghana from 2008 to 2013, and analysed them phylogenetically with a global collection of G2P[4] strains and African non-G2P[4] DS-1-like strains. The genotype constellation of the study strains was G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Strains from the same season were highly identical across the whole genome while strains from different seasons were more divergent from each other. The VP7, VP4, VP2, NSP1, and NSP5 genes belonged to lineage IVa; the VP6, VP1, NSP2, and NSP3 genes belonged to lineage V, and all these genes evolved in the same fashion as the global strains. In the NSP4 gene, lineages V (2008) and X (2009) were replaced by VI (2012/2013) whereas in the VP3 gene, lineage V (2008/2009) was replaced by VII (2012/2013) and these replacements coincided with the vaccine introduction period (2012). The evolutionary rate of the NSP4 gene was 1.2×10-3 substitutions/site/year and was rather comparable to that of the remaining 10 genes. The multiple NSP4 lineages were explained by intra-genotype reassortment with co-circulating African human DS-1-like strains bearing G2[6], G3P[6], G6[6] and G8. There was no explicit evidence of the contribution of animal RVA strains to the genome of the Ghanaian G2P[4] strains. In summary, this study revealed the dynamic evolution of the G2P[4] strains through intra-genotype reassortment events leading to African specific lineages such IX and X in the NSP4 gene. So far, there was no evidence of a recent direct involvement of animal RVA genes in the genome diversity of African G2P[4] strains.

Changes in the distribution of lineage constellations of G2P[4] Rotavirus A strains detected in Japan over 32 years (1980-2011).

Rotavirus A (RVA) is a leading cause of acute gastroenteritis in young children worldwide. Most human RVA strains are classified into three major genotype constellations: Wa-like, DS-1-like and AU-1-like. The evolution of G2P[4] strains possessing the DS-1-like genetic background was described in a few recent studies. However, the strains analyzed in these studies were almost exclusively the ones detected after 2000. In recognition of the scarcity of G2P[4] strains detected before 2000 for which whole genome information was available, this study was undertaken to characterize 19 Japanese G2P[4] strains detected between 1983 and 1990 (14 strains) and between 2001 and 2011 (5 strains), and to compare them with 131 G2P[4] strains from across the world. The Japanese strains along with the strains elsewhere in the world underwent stepwise changes from lineage I to IVa in 5 genes (the VP7, VP4, VP2, NSP1 and NSP5 genes) and from lineage I to V in 6 genes (the VP6, VP1, VP3, NSP2, NSP3 and NSP4 genes). Furthermore, G2P[4] strains detected after 2004 appeared to have undergone further intragenotype reassortment, resulting in the emergence of lineage V in the VP7 gene, and VI and VII in the VP3 and NSP4 genes. The time of the most recent common ancestor (tMRCA) for the emergent lineages VI and VII was estimated to be around the early 2000s. However, the year when the ancestor of the emergent lineages diverged from that of the rest of the lineages in the respective genes preceded the tMRCA 80-90 years. The origin of the emergent lineages is likely to be human RVA strains possessing genotypes other than G2P[4], and not RVA strains of an animal origin. In conclusion, stepwise changes in lineages imparted new genomic constellations to G2P[4] strains, which appears to have contributed to their successful spread across the globe, most notably since 2004.

Group a rotavirus and norovirus genotypes circulating in the northeastern Brazil in the post-monovalent vaccination era.

Group A rotaviruses (RVA) and noroviruses (NoV) are the leading cause of acute gastroenteritis (AGE) worldwide. Childhood diarrhea deaths and hospital admissions have declined since the introduction of the monovalent (G1P[8]) vaccine (Rotarix(®) [RV1]) in the National Immunization Program in Brazil in 2006. This study aims to investigate the epidemiological profile of NoV and RVA infections from children with AGE in the Northeastern region of Brazil in the post vaccine season. Two-hundred fecal samples collected from children up to 10 years old in Fortaleza, Ceará between 2008-2009 were screened for the presence of RVA and NoV. Positive samples were genotyped and sequenced. The RVA screening revealed 12% prevalence and all RVA strains belonged to G2P[4] genotype. Phylogenetic analysis based on the 11 RVA genome segments sequenced from eight samples revealed a DS-1-like genotype constellation: I2-R2-C2-M2-A2-N2-T2-E2-H2. For NoV screening, the prevalence observed was 17% and the following genotypes were detected: GII.4 (59%), GII.12 (17%), GII.6 (9%), GII.3 (6%), and GII.? (9%). At least four different NoVs genotypes and two RVA G2P[4] variants were identified circulating in the Northeastern region of Brazil. RVA phylogenetic analysis suggests that the RVA G2P[4] strains might have originated from intragenogroup reassortment events. Whether the genetic modifications observed in these contemporary G2P[4] RVA strains may impact the long-term effectiveness of the current vaccination programs remains to be explored. These data reinforce the importance of surveillance for monitoring the emergence of new strains of RVA and NoV and their impact on cases of acute gastroenteritis.

Prevalence and genomic characterization of G2P[4] group A rotavirus strains during monovalent vaccine introduction in Brazil.

This study aims to: estimate the prevalence of G2P[4] rotaviruses in Brazil between 2001-2011 from patients with acute gastroenteritis; perform phylogenetic analyses of G2P[4] Brazilian strains (from vaccinated and non-vaccinated children) based on VP7 and VP8(∗) encoding genes and analyze the antigenic regions of these proteins comparing with RV1; and assess the full genetic background of eleven selected Brazilian strains. The G2P[4] detection rate among RVA positive samples was 0/157 in 2001, 3/226 (1.3%) in 2002, 0/514 in 2003, 0/651 in 2004, 31/344 (9%)/2005, 112/227 (49%)/2006, 139/211 (66%)/2007, 240/284 (85%)/2008, 66/176 (37.5%)/2009, 367/422 (87%)/2010 and 75/149 (50%)/2011. For the VP7 and VP8(∗) encoding genes, 52 sequences were analyzed and shared up to 99% nucleotide identity with other contemporary G2P[4] strains detected worldwide, grouping into different clusters. Most differences inside antigenic epitopes of VP7 and VP8(∗) have been maintained in the G2P[4] Brazilian strains along the years, and all were present before RV1 introduction. Eleven G2P[4] strains (4-vaccinated/7-non-vaccinated) were completely characterized and possessed the typical DS-1-like genotype constellation (G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2) sharing up to 99% of nucleotide identity with contemporary worldwide strains. Reassortments between Brazilian G2P[4] human strains were observed. In conclusion, the data obtained in the current study suggests that implementation of RV1 vaccination might not influence the genetic diversity observed in G2P[4] analyzed strains. Several factors might have contributed to the increased prevalence of this genotype in Brazil since 2005: the introduction of RV1 into the Brazilian National Immunization Program has resulted in a decrease in the relative prevalence of predominant Wa-like RVA strains facilitating the increase of the heterotypic (DS-1-like) RVA strain G2P[4] in the Brazilian population; the genetic diversity found in different geographical regions throughout the years before, and after the introduction of RV1; the long period of low or no circulation of this genotype in Brazil previous to RV1 introduction could have created favorable conditions for the accumulation of immunological susceptible individuals.

Characterization of G2P[4] rotavirus strains causing outbreaks of gastroenteritis in the Northern Territory, Australia, in 1999, 2004 and 2009.

Outbreaks of rotavirus diarrhea cause a large disease burden in the Alice Springs region of the Northern Territory, Australia. The introduction of the rotavirus vaccine Rotarix® has been associated with an increase in detection of G2P[4] strains in many countries. However, G2P[4] emergence has also been observed in vaccine-naive countries, suggesting a general global increase in the circulation of G2P[4] strains. A G2P[4] rotavirus outbreak occurred in 2009, 28 months after the introduction of the Rotarix® vaccine and 43 children were hospitalized. Pre-vaccine introduction, G2P[4] strains were observed associated with large outbreaks in 1999 and 2004. To determine the genetic relationship between these strains whole genome sequence analysis was conducted on representative strains from each of the G2P[4] outbreaks, in 1999, 2004 and 2009. Phylogenetic analysis revealed the majority of genes from 2009 outbreak strain clustered with contemporary global strains, while the VP7 gene clustered with contemporary and older strains and was antigenically distinct to the majority of contemporary global G2P[4] strains; suggesting the strain was an intragenogroup reassortant. The 1999 and 2009 strains appear to share similar evolutionary origins, and both had a high degree of genetic identity to previously identified Australian and global strains. Conversely, the 2004 outbreak strain was more divergent in comparison to Australian and global strains. The 1999 and 2004 outbreaks likely occurred due to the accumulation of immunologically naïve children in the population following low levels of G2P[4] rotavirus disease in the community in the years prior to each outbreak. The 2009 outbreak was associated with moderate vaccine coverage in the population and vaccine efficacy against the strain was low. The circulation of this unusual strain in the population combined with low vaccine coverage and diminished vaccine efficacy likely contributed to the outbreak occurring in this population.

Longitudinal analysis of VP7 gene of group A human rotavirus G2P[4] strains circulating in the pre-vaccine era in Sapporo, Japan from 1991 to 2011.

Sequence analysis of the VP7 gene in 23 group A human rotavirus G2P[4] strains obtained during 1991-2011, that is, the pre-vaccine era, in Sapporo, Japan showed considerable genetic diversity, mainly in variable regions. Recent G2P[4] epidemic strains were located in sublineage IVa with a distinctive substitution of D96N. This study provides background data on the genetic variability of G2P[4] rotavirus-VP7 gene prior to the widespread use of rotavirus vaccines in Japan.

Characterization of G2P[4] rotavirus strains associated with increased detection in Australian states using the RotaTeq® vaccine during the 2010-2011 surveillance period.

The introduction of rotavirus vaccines Rotarix® and RotaTeq® into the Australian National Immunisation Program in July 2007 has resulted in a dramatic decrease in the burden of rotavirus disease. G2P[4] strains became the dominant genotype Australia-wide during the 2010-2011 surveillance period and for the first time since vaccine introduction, a higher proportion were isolated in jurisdictions using RotaTeq® vaccine compared to locations using Rotarix®. Phylogenetic analysis of the VP7 gene of 32 G2P[4] strains identified six genetic clusters, these distinct clusters were also observed in the VP4 gene for a subset of 12 strains. The whole genome was determined for a representative strain of clusters; A (RVA/Human-wt/AUS/SA066/2010/G2P[4]), B (RVA/Human-wt/AUS/WAPC703/2010/G2P[4]), C (RVA/Human-wt/AUS/MON008/2010/G2P[4]) and E (RVA/Human-wt/AUS/RCH041/2010/G2P[4]). All of the strains possessed the archetypal DS-1 like genome constellation G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Three of the strains, SA066, MON008 and WAPC703 clustered together and were distinct to RCH041 for all 11 genes. The VP7 genes of 31/32 of the strains characterized in this study possessed five conserved amino acid substitutions when compared to the G2 VP7 gene present in the RotaTeq® vaccine. Three of the substitutions were in the VP7 antigenic regions A and C, the substitutions A87T, D96N and S213D have been reported in the majority of G2P[4] strains circulating globally over the previous decade. These changes may have improved the ability of strains to circulate in settings of high vaccine use.

Higher proportion of G2P[4] rotaviruses in vaccinated hospitalized cases compared with unvaccinated hospitalized cases, despite high vaccine effectiveness against heterotypic G2P[4] rotaviruses.

The overall vaccine effectiveness of the monovalent rotavirus vaccine in an observational, prospective, multicentre, hospital-based case-control study in Belgium (RotaBel) was 90%. However, rotavirus genotype and co-infecting pathogens are important parameters to take into account when assessing vaccine effectiveness. In this study we specifically investigated the effect of rotavirus genotypes and co-infecting pathogens on vaccine effectiveness of the monovalent vaccine. In addition, we also investigated the effect of co-infecting pathogens on disease severity. From February 2008 to June 2010 stool samples of rotavirus gastroenteritis cases of a random sample of 39 Belgian hospitals were collected and subsequently genotyped. Fisher's exact tests were performed to investigate the relationships between rotavirus genotype, co-infecting pathogens and disease severity. The vaccine effectiveness of a full series of the monovalent rotavirus vaccine against hospitalized rotavirus gastroenteritis caused by G1P[8] rotavirus strains was 95% (95% CI 77.5-98.7). Against G2P[4], the vaccine effectiveness was 85% (95% CI: 63.7-93.8). G4P[8]- and G3P[8]-specific vaccine effectiveness was 90% (95% CI 19.2-98.7) and 87% (95% CI -5.2 to 98.4), respectively. A post-hoc analysis showed that the genotype distribution was significantly related to the vaccination status (p <0.001), whereby G2P[4] strains were proportionally more prevalent in vaccinated cases than in unvaccinated cases. No statistical associations were found between co-infection status and vaccination status, Vesikari severity score or rotavirus genotype. The high vaccine effectiveness against the individual genotypes implies robust protection of the monovalent rotavirus vaccine against hospitalized rotavirus gastroenteritis caused by the major human rotavirus genotypes. The prevalence of G2P[4] requires continued monitoring.