Vaccines for preventing rotavirus diarrhoea: vaccines in use

Combatting infectious diarrhea: innovations in treatment and vaccination strategies

INTRODUCTION

The escalating prevalence of infectious diseases is an important cause of concern in society. Particularly in several developing countries, infectious diarrhea poses a major problem, with a high fatality rate, especially among young children. The condition is divided into four classes, namely, acute diarrhea, invasive diarrhea, acute bloody diarrhea, and chronic diarrhea. Various pathogenic agents, such as bacteria, viruses, protozoans, and helminths, contribute to the onset of this condition.

AREAS COVERED

The review discusses the scenario of infectious diarrhea, the prevalent types, as well as approaches to management including preventive, therapeutic, and vaccination strategies. The vaccination techniques are extensively discussed including the available vaccines, their advantages as well as limitations.

EXPERT OPINION

There are several approaches available to develop new-improved vaccines. In addition, route of immunization is important and aerosols/nasal sprays, oral route, skin patches, powders, and liquid jets to minimize needles can be used. Plant-based vaccines, such as rice, might save packing and refrigeration costs by being long-lasting, non-refrigerable, and immunogenic. Future research should utilize predetermined PCR testing intervals and symptom monitoring to identify persistent pathogens after therapy and symptom remission.

Anti-rotavirus antibody measurement in a rotavirus vaccine trial: Choice of vaccine antigen in immunoassays does matter

In a clinical trial of Bangladeshi infants who received three doses of RotaTeq (ages 6, 10, and 14 weeks), we did a head-to-head assessment of two vaccine virus strains to measure rotavirus IgA in sera. Serum samples collected at pre-dose 1 (age 6 weeks) and post-dose 3 (age 22 weeks) were tested for rotavirus IgA by EIA by using the matching vaccine strain (RotaTeq) and a different vaccine strain (Rotarix) as antigens. Overall, rotavirus IgA seropositivity and titers with each antigen were compared. At age 22 weeks (N = 531), the proportion of infants who tested rotavirus IgA seropositive was similar when measured using the RotaTeq (412/531 [78%]) or the Rotarix antigen (403/531 [76%]) in the EIA. However, the IgA geometric mean titer was higher when measured using the RotaTeq antigen as compared to that measured using the Rotarix antigen [218 (95%CI: 176-270) vs. 93 (77-111), p < .0001]. We have compared two globally licensed vaccines, the human monovalent, and the pentavalent reassortant, as antigens on a RotaTeq cohort, resulting in higher estimations of IgA antibodies in the same sample when measured using the RotaTeq antigen. Our findings support matching vaccine antigens in EIA for the most desired immunogenicity testing of the RotaTeq vaccine.

mRNA-based VP8* nanoparticle vaccines against rotavirus are highly immunogenic in rodents

Despite the availability of live-attenuated oral vaccines, rotavirus remains a major cause of severe childhood diarrhea worldwide. Due to the growing demand for parenteral rotavirus vaccines, we developed mRNA-based vaccine candidates targeting the viral spike protein VP8*. Our monomeric P2 (universal T cell epitope)-VP8* mRNA design is equivalent to a protein vaccine currently in clinical development, while LS (lumazine synthase)-P2-VP8* was designed to form nanoparticles. Cyro-electron microscopy and western blotting-based data presented here suggest that proteins derived from LS-P2-VP8* mRNA are secreted in vitro and self-assemble into 60-mer nanoparticles displaying VP8*. mRNA encoded VP8* was immunogenic in rodents and introduced both humoral and cellular responses. LS-P2-VP8* induced superior humoral responses to P2-VP8* in guinea pigs, both as monovalent and trivalent vaccines, with encouraging responses detected against the most prevalent P genotypes. Overall, our data provide evidence that trivalent LS-P2-VP8* represents a promising mRNA-based next-generation rotavirus vaccine candidate.

T7 expression plasmids for producing a recombinant human G1P[8] rotavirus comprising RIX4414 sequences of the RV1 (Rotarix , GSK) vaccine strain

The live oral rotavirus RV1 (Rotarix) vaccine is formulated from the human G1P[8] RIX4414 virus. Based on RIX4414 sequences, T7 expression plasmids were constructed that supported recovery of recombinant RIX4414-like viruses by reverse genetics. These plasmids will advance the study of the RV1 vaccine, possibly allowing improvements to its efficacy.

The success of publicly funded rotavirus vaccine programs for preventing community- and hospital-acquired rotavirus infections in Canadian pediatric hospitals: an observational study

BACKGROUND

Canadian immunization programs for rotavirus started in 2011. We sought to determine their effect on the burden of community-acquired admissions and hospital-acquired rotavirus at pediatric hospitals.

METHODS

The Canadian Immunization Monitoring Program Active (IMPACT) network conducted active surveillance for rotavirus-positive hospital admissions between 2005 and 2020 at 12 pediatric hospitals. We used yearly rates of community-acquired rotavirus per 10 000 admissions and hospital-acquired rotavirus infections per 1000 patient-days to determine changes in the pre- and post-vaccine program periods.

RESULTS

During the 15-year study period, 5691 rotavirus hospital admissions and hospital-acquired infections were detected, including 4323 (76%) community-acquired infections and 1368 (24%) hospital-acquired infections. The average community-acquired rate in the pre-vaccine period was 60.3 (95% confidence interval [CI] 53.7-68.3) per 10 000 admissions, with a decline to 11.0 (95% CI 7.5-15.1) per 10 000 admissions in the post-vaccine period, resulting in an average reduction of 81.7% (95% CI 74.4%-87.8%). The rate of hospital-acquired rotavirus declined from 0.35 (95% CI 0.29-0.41) per 1000 patient-days in the pre-vaccine period to 0.05 (95% CI 0.03-0.07) per 1000 patient-days in the post-vaccine period, resulting in an 85.3% (95% CI 77.7%-91.9%) average decline. Herd protection was present among children aged 2-16 years.

INTERPRETATION

Although start dates of rotavirus vaccine programs across provinces varied, there was around an 80% average decrease in both community-acquired and hospital-acquired rotavirus infections at pediatric hospitals in Canada in the 1- to 9-year interval after implementation of rotavirus vaccine programs. Herd protection is an important aspect of rotavirus vaccines for other children who are not vaccine eligible, and rotavirus vaccines continue to provide important benefits both for children and health care systems.

Healthy Drinking Water as a Necessity in Developing Countries Like India: A Narrative review

Water is an indispensable part of human life. This article is an extensive review that focuses on the importance of water to sustain human life, the necessity of healthy, safe drinking water, and the health hazards of drinking untreated and contaminated water. We drink treated water thinking it to be safe without the knowledge that it, too, has harmful effects. Detrimental health effects due to water chlorination are mentioned in this article. The usage of nanoparticles for the treatment of water is an alternative to chlorination, but they are little in use as they are expensive. Transmission of waterborne diseases through drinking water is widespread in a developing country like India. A list of the pathogens contaminating drinking water is present in the review. Pathogens pollute water, and heavy metals and chemicals from industries, pesticides, pharmaceutical compounds, and radioactive waste also taint it. The harmful effects of metal and chemical toxicities on human health are discussed in this review. The government of India has launched several programmes to ensure clean, safe drinking water for all its residents. The study reflects on the treatment given to individuals suffering from waterborne diseases in India. Significant changes in health status in India have been seen recently after the execution of various government programmes to provide safe, healthy drinking water to all its residents.

Whole-genome characterization of common rotavirus strains circulating in Vellore, India from 2002 to 2017: emergence of non-classical genomic constellations

Rotaviruses (RVs) are the most common etiological agent of acute gastroenteritis among young children, even after vaccine introduction in low-income countries. A whole-genome classification representing the 11 RV genes, was introduced for surveillance and characterization of RVs. This study characterized the common circulating strains in Vellore, India from 2002 to 2017 to understand rotavirus strain diversity and evolution using Whole genome sequencing (WGS) carried out on Illumina MiSeq. The 89% (92% of Wa-like, 86% of DS-1-like) of strains had classical constellations, while reassortant constellations were seen in 11% (8% of Wa-like, 14% of DS-1-like) of the strains. The rare E6-NSP4 in combination with DS-1 like G1P[8] and the emergence of the OP-354 subtype of P[8] were identified. Phylogenetics of RV strains revealed multiple subtypes circulating in the past 15 years, with strong evidence of animal to human gene transmission among several strains.

Immunogenicity and safety of a new hexavalent rotavirus vaccine in Chinese infants: A randomized, double-blind, placebo-controlled phase 2 clinical trial

Rotavirus remains a major cause of diarrhea among 5-y-old children, and vaccination is currently the most effective and economical measure. We conducted a randomized, double-blind, placebo-controlled phase II clinical trial designed to determine the dosage, immunogenicity, and safety profile of a novel hexavalent rotavirus vaccine. In total, 480 eligible healthy infants, who were 6-12 weeks of age at the time of randomization were randomly allocated (1:1:1) to receive 105.5 focus-forming unit (FFU) or 106.5FFU of vaccine or placebo on a 0, 28 and 56-d schedule. Blood samples were collected 28 d after the third dose to assess rotavirus immunoglobulin A (IgA) antibody levels. Adverse events (AEs) up to 28 d after each dose and serious adverse events (SAEs) up to 6 months after the third dose were recorded as safety measurements. The anti-rotavirus IgA seroconversion rate of the vaccine groups reached more than 70.00%, ranging from 74.63% to 76.87%. The postdose 3 (PD3) geometric mean concentrations (GMCs) of anti-rotavirus IgA among vaccine recipients ranged from 76.97 U/ml to 84.46 U/ml. At least one solicited AE was recorded in 114 infants (71.25%) in the high-dose vaccine group, 106 infants (66.25%) in the low-dose vaccine group and 104 infants (65.00%) in the placebo group. The most frequently solicited AE was fever. The novel oral hexavalent rotavirus vaccine was safe and immunogenic in infants support the conclusion to advance the candidate vaccine for phase 3 efficacy trials.

Cost-effectiveness analysis measuring the total costs against the health benefits of three different rotavirus vaccines for Mexico

Rotavirus (RV) infection causes acute rotavirus gastroenteritis (RVGE) in infants. Safe and effective RV vaccines are available, of which Mexico has included one in its national immunization program (NIP) since 2007. Health outcome gains, expressed in quality-adjusted life years (QALYs), and cost improvements are important additional factors for the selection of a NIP vaccine. These two factors were analyzed here for Mexico over one year implementing three RV vaccines: 2-dose Rotarix (HRV), versus 3-dose RotaTeq (HBRV), and 3-dose Rotasiil (BRV-PV), presented in a 1-dose or 2-dose vial). HRV would annually result in discounted QALY gains of 263 extra years compared with the other vaccines by averting an extra 24,022 homecare cases, 10779 medical visits, 392 hospitalizations, and 12 deaths. From a payer's perspective and compared with HRV, BRV-PV 2-dose vial and BRV-PV 1-dose vial would annually result in $13.5 million and $4.6 million net savings, respectively, while HBRV would result in $3.4 million extra costs. The societal perspective may also show savings compared with HRV for BRV-PV 2-dose vial of $4.9 million, while BRV-PV 1-dose vial and HBRV may show extra costs of $4.0 million and $12.1 million respectively. HRV and HBRV were both approved in Mexico, with HRV requiring less investment than HBRV with higher QALY gains and cost savings. The HRV vaccine produced those higher health gains due to its earlier protection and greater coverage achieved after its schedule completion with two doses only, providing full protection at four months of age instead of longer periods for the other vaccines.

M. Eljaro Z, Abu-Awwad F, Bozya Y, Hjaija D, Bhat N, Leader T, Ramlawi A, Marzouqa H. Introducing ROTAVAC® to the occupied Palestinian Territories: Impact on diarrhea incidence, rotavirus prevalence and genotype composition

BACKGROUND

Rotavirus infection remains an important cause of morbidity and mortality in children. The introduction of vaccination programs in more than 100 countries has contributed to a decrease in hospitalizations and mortality. This study investigates the epidemiological impact of the rotavirus vaccine ROTAVAC® in the Palestinian Territories, the first country to switch from ROTARIX® to this new vaccine.

METHODS

Clinical surveillance data was collected fromchildren younger than 5attendingoutpatient clinics throughout Gaza withdiarrhea between 2015 and 2020. The incidence of all-cause diarrhea was assessed using an interrupted time-series approach. Rotavirus prevalence was determined at the Caritas Baby Hospital in the West Bank usingELISA on stool specimen of children younger than 5with diarrhea. Genotyping was performed on 325 randomly selected rotavirus-positive samples from January 2015 through December 2020 using multiplex PCR analysis.

RESULTS

Average monthly diarrhea casesdropped by 16.7% annually fromintroduction of rotavirus vaccination in May 2016 to the beginning of the SARS-CoV-2 epidemic in March 2020 for a total of 53%. Case count declines were maintained afterthe switchto ROTAVAC® in October 2018. Rotavirus positivity in stool samples declined by 67.1% over the same period without change followingthe switch to ROTAVAC®. The distribution of predominant genotypes in rotavirus-positive stool samples changed from a pre-vaccination G1P [8] to G9P[8] and G12P[8] during the ROTARIX® period and G2P[4] after the introduction of ROTAVAC®.

CONCLUSION

ROTAVAC® has shown epidemiological impact on par with ROTARIX® after its introduction to the national immunization schedule in the Palestinian Territories. A molecular genotype shift from a pre-vaccination predominance of G1P[8] to a current predominance of G2P[4] requires more long-term surveillance.

Сost-effectiveness of pentavalent rotavirus vaccination in the Russian Federation

   One of the main causes of acute gastroenteritis in children under 5 years of age is rotavirus infection (RVI). Vaccines against RVI significantly reduce the incidence.   Aim. To evaluate the cost-effectiveness of mass vaccination of children with a 5-valent RVI vaccine in the Russian Federation.   Materials and methods. The assessment was carried out using modeling based on published data on the effectiveness of the vaccine and epidemiological indicators in the Russian Federation. The analysis was carried out from the perspective of the health care system and society as a whole with a 5-year horizon. The cost of RVI therapy corresponded to the compulsory health insurance tariffs for St. Petersburg for 2022, the price of 1 dose of the vaccine was the registered price, including VAT. Costs and life expectancy, taking into account quality, were discounted at 3.5 % per year.   Results. Given the assumptions made, routine vaccination will prevent an average of 468,637 cases of RVI over 5 years. Avoided direct medical costs, i. e. RVI treatment costs will amount to 53,4 %, and lost income due to temporary disability – 46,6 % of the total avoided costs. At the same time, the volume of avoided costs is 61,4 % due to a decrease in morbidity in the vaccinated population, and 38.6 % due to the development of a indirect effect. The predicted avoided costs per 1 vaccinated person is 2,975 thousand rubles. From a societal perspective, the cost-effectiveness of the Rota-V-Aid vaccine will be 364,813 thousand rubles / QALY (quality-adjusted life year), and from a healthcare perspective – 1726,399 thousand rubles / QALY. Thus, in both cases, the cost-effectiveness of RVI vaccination will not exceed the generally accepted threshold of willingness to pay, equal to three times the gross domestic product per capita in the Russian Federation (according to data for 2021 – ~2,7 million rubles). The predicted cost-effectiveness of selective vaccination is significantly lower than that of mass vaccination.   Conclusions. Mass vaccination of children with a 5-valent vaccine against RVI will not only reduce the incidence in the Russian Federation, but, taking into account the assumptions made, can also be considered as a cost-effective intervention.

The Value of Rotavirus Vaccination in Europe: A Call for Action

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has pushed many healthcare systems into crisis. High vaccine coverage amongst children reduces emergency room presentations, hospital admissions and deaths due to vaccine-preventable diseases, freeing up healthcare resources including polymerase chain reaction testing for patients with SARS-CoV-2. In Europe, rotavirus gastroenteritis leads to 75,000-150,000 hospitalisations and up to 600,000 medical encounters annually. Nevertheless, in 2022, only 18 countries in Europe (out of 38) have a publicly funded routine universal mass immunisation programme against rotavirus gastroenteritis. Evidence available in the last few years re-emphasises that rotavirus vaccines currently available in Europe are highly effective, preventing up to 96% of rotavirus-related hospitalisations in children less than 1 year of age (potentially 72,000-144,000 hospitalisations Europe-wide). Long-term surveillance indicates that rotavirus vaccination does not result in an overall increase in intussusception. On the contrary, increasing evidence suggests an overall reduction in intussusception in the first 12 months of life when early, high rotavirus vaccine coverage is achieved. Prevention of rotavirus gastroenteritis has marked positive impacts on parental wages and government tax revenue, with benefits extending across the whole economy. In the SARS-CoV-2 pandemic setting there is a new imperative to achieve high levels of paediatric vaccination against vaccine-preventable diseases, including rotavirus gastroenteritis. The introduction of rotavirus universal mass vaccination can be expected to reduce the number of preventable illnesses, hospitalisations and deaths caused by rotavirus gastroenteritis. Reducing vaccine-preventable diseases is particularly urgent at this time when healthcare systems are preoccupied and overwhelmed with SARS-CoV-2. Graphical abstract available for this article.

Genetic heterogeneity of group A rotaviruses: a review of the evolutionary dynamics and implication on vaccination

INTRODUCTION

Human rotavirus remains a major etiology of acute gastroenteritis among under 5-year children worldwide despite the availability of oral vaccines. The genetic instability of rotavirus and the ability to form different combinations from the different G- and P-types reshapes the antigenic landscape of emerging strains which often display limited or no antigen identities with the vaccine strain. As evidence also suggests, the selection of the antigenically distinct novel or rare strains and their successful spread in the human population has raised concerns regarding undermining the effectiveness of vaccination programs.

AREAS COVERED

We review aspects related to current knowledge about genetic and antigenic heterogeneity of rotavirus, the mechanism of genetic diversity and evolution, and the implication of genetic change on vaccination.

EXPERT OPINION

Genetic changes in the segmented genome of rotavirus can alter the antigenic landscape on the virion capsid and further promote viral fitness in a fully vaccinated population. Against this background, the potential risk of the appearance of new rotavirus strains over the long term would be better predicted by a continued and increased close monitoring of the variants across the globe to identify any change associated with disease dynamics.

Impact after the Change from Voluntary to Universal Oral Rotavirus Vaccination on Consecutive Emergency Department Visits for Acute Gastroenteritis among Children in Kobe City, Japan (2016-2022)

Rotavirus (RV) is the leading cause of acute gastroenteritis (AGE), particularly in infants. In 2006, the high efficacy of oral RV vaccines (RVVs, RotarixTM and RotaTeqTM) was demonstrated. Voluntary RVV started in Japan in 2011, and in October 2020 were launched as universal oral RVVs in Japan. However, the impact of changes from voluntary to universal RVVs has not been studied in a primary emergency medical center in Japan. We investigated changes in the number of pediatric patients with AGE after introducing universal RVVs in our center. A clinical database of consecutive patients aged <16 who presented to Kobe Children’s Primary Emergency Medical Center between 1 April 2016 and 30 June 2022 was reviewed. After implementing universal RVVs, fewer children presented with RV-associated AGE (the reduction of proportion of the patients in 2022 was −61.7% (all ages), −57.9% (<1 years), −67.8% (1−<3 years), and −61.4% (3−<5 years) compared to 2019). A similar decrease in those of age who were not covered by the universal RVV was observed. There was a significant decline in the number of patients with AGE during the RV season who presented to the emergency department after implementing universal RVVs.

Impact and cost-effectiveness of rotavirus vaccination in Niger: a modelling study evaluating alternative rotavirus vaccines

OBJECTIVES

To evaluate the cost-effectiveness of alternative rotavirus vaccines in Niger, using UNIVAC, a proportionate outcomes model.

SETTING

The study leverages global, regional and local data to inform cost-effectiveness modelling. Local data were collected as part of a clinical trial taking place in the Madarounfa district, Maradi region, Niger.

PARTICIPANTS

The study models impact of infants vaccination on rotavirus gastroenteritis in children under 5 years of age.

INTERVENTIONS

We compared the use of ROTARIX (GlaxoSmithKline, Belgium), ROTAVAC (Bharat Biotech, India) and ROTASIIL (Serum Institute, India) to no vaccination and to each other over a 10-year period starting in 2021.

RESULTS

We estimated that ROTARIX, ROTAVAC and ROTASIIL would each prevent 13 million cases and 20 000 deaths of children under 5 years over a 10-year period in Niger. Compared with no vaccination, the cost to avert a disability-adjusted life-year was US$146 with ROTARIX, US$107 with ROTASIIL and US$76 with ROTAVAC from the government perspective. ROTAVAC dominated ROTARIX and ROTASIIL (eg, provided similar or higher benefits at a lower cost) and had 90% chance to be cost-effective at a US$100 willingness-to-pay threshold.

CONCLUSIONS

This study can inform decision-making around rotavirus vaccination policy in Niger, demonstrating that ROTAVAC is likely the most cost-effective option. Alternative products (ROTASIIL and ROTARIX) may also be considered by decision-makers if they are priced more competitively, or if their cold chain requirements could bring additional economic benefits.

Genomic and evolutionary characteristics of G9P[8], the dominant group a rotavirus in China (2016–2018)

G9P[8] became the predominant rotavirus A (RVA) genotype in China in 2012. To evaluate its genetic composition at the whole-genome level, 115 G9P[8] RVA strains isolated from children under 5 years old were sequenced and characterized. All 13 strains in 2016 and 2017 and an additional 54 strains in 2018 were genotyped as G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. The other 48 strains in 2018 were all genotyped as G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1, with the NSP4 gene characterized as a DS-1-like genotype. The time of the most recent common ancestor (tMRCA) and evolution rates of the VP7, VP4, and NSP4 (E1 and E2) genes of these strains were estimated by Bayesian evolutionary dynamics analysis. We estimated the evolution rates (nt substitutions per site per year) as 1.38 × 10^–3 [the 95% highest posterior density (HPD) was 1.09–1.72 × 10^–3] for VP7, 0.87 × 10^–3 (95% HPD: 0.75–1.00 × 10^–3) for VP4, 0.56 × 10^–3 (95% HPD: 0.41–0.73 × 10^–3) for NSP4-E1, and 1.35 × 10^–3 (95% HPD: 0.92–1.86 × 10^–3) for NSP4-E2. The tMRCA was estimated to be 1935.4 (95% HPD: 1892.4–1961.3) for VP7, 1894.3 (95% HPD: 1850.5–1937.8) for VP4, 1929.4 (95% HPD: 1892.4–1961.3) for NSP4-E1, and 1969.2 (95% HPD: 1942.2–1985.3) for NSP4-E2. The baseline genetic information in this study is expected to improve our understanding of the genomic and evolutionary characteristics of the rotavirus genome. Furthermore, it will provide a basis for the development of next-generation rotavirus vaccines for humans.

Differentiation between Wild-Type Group A Rotaviruses and Vaccine Strains in Cases of Suspected Horizontal Transmission and Adverse Events Following Vaccination

Human group A rotaviruses (RVA) are important enteric pathogens, as they are a leading cause of acute gastroenteritis (AGE) in children worldwide. Since 2013, the German Standing Committee on vaccination recommended the routine rotavirus vaccination for infants in Germany. While vaccination has significantly decreased RVA cases and worldwide mortality, in some cases, infants can develop acute gastroenteritis as an adverse reaction after immunization with an attenuated live vaccine. Pediatricians, as well as clinicians and diagnostic laboratories, contacted the Consultant Laboratory for Rotaviruses and inquired whether cases of RVA-positive AGE after vaccination were associated with vaccine or with wild-type RVA strains. A testing algorithm based on distinguishing PCRs and confirmative sequencing was designed, tested, and applied. Diagnostic samples from 68 vaccinated children and six cases where horizontal transmission was suspected were investigated in this study. Using a combination of real-time PCR, fragment-length analysis of amplicons from multiplex PCRs and confirmative sequencing, vaccine-like virus was detected in 46 samples and wild-type RVA was detected in 6 samples. Three mixed infections of vaccine and wild-type RVA were detectable, no RVA genome was found in 19 samples. High viral loads (>1.0 × 107 copies/g stool) were measured in most RVA-positive samples. Furthermore, information on co-infections with other AGE pathogens in the vaccinated study population was of interest. A commercial multiplex PCR and in-house PCRs revealed three co-infections of vaccinated infants with bacteria (two samples with Clostridioides difficile and one sample with enteropathogenic E. coli) and six co-infections with norovirus in a subset of the samples. Human astrovirus was detected in one sample, with suspected horizontal transmission. The cases of suspected horizontal transmission of vaccine RVA strains could not be confirmed, as they either involved wild-type RVA or were RVA negative. This study shows that RVA-positive AGE after vaccination is not necessarily associated with the vaccine strain and provides a reliable workflow to distinguish RVA vaccine strains from wild-type strains.

Using Species a Rotavirus Reverse Genetics to Engineer Chimeric Viruses Expressing SARS-CoV-2 Spike Epitopes

Species A rotavirus (RVA) vaccines based on live attenuated viruses are used worldwide in humans. The recent establishment of a reverse genetics system for rotoviruses (RVs) has opened the possibility of engineering chimeric viruses expressing heterologous peptides from other viral or microbial species in order to develop polyvalent vaccines. We tested the feasibility of this concept by two approaches. First, we inserted short SARS-CoV-2 spike peptides into the hypervariable region of the simian RV SA11 strain viral protein (VP) 4. Second, we fused the receptor binding domain (RBD) of the SARS-CoV-2 spike protein, or the shorter receptor binding motif (RBM) nested within the RBD, to the C terminus of nonstructural protein (NSP) 3 of the bovine RV RF strain, with or without an intervening Thosea asigna virus 2A (T2A) peptide. Mutating the hypervariable region of SA11 VP4 impeded viral replication, and for these mutants, no cross-reactivity with spike antibodies was detected. To rescue NSP3 mutants, we established a plasmid-based reverse genetics system for the bovine RV RF strain. Except for the RBD mutant that demonstrated a rescue defect, all NSP3 mutants delivered endpoint infectivity titers and exhibited replication kinetics comparable to that of the wild-type virus. In ELISAs, cell lysates of an NSP3 mutant expressing the RBD peptide showed cross-reactivity with a SARS-CoV-2 RBD antibody. 3D bovine gut enteroids were susceptible to infection by all NSP3 mutants, but cross-reactivity with SARS-CoV-2 RBD antibody was only detected for the RBM mutant. The tolerance of large SARS-CoV-2 peptide insertions at the C terminus of NSP3 in the presence of T2A element highlights the potential of this approach for the development of vaccine vectors targeting multiple enteric pathogens simultaneously. IMPORTANCE We explored the use of rotaviruses (RVs) to express heterologous peptides, using SARS-CoV-2 as an example. Small SARS-CoV-2 peptide insertions (<34 amino acids) into the hypervariable region of the viral protein 4 (VP4) of RV SA11 strain resulted in reduced viral titer and replication, demonstrating a limited tolerance for peptide insertions at this site. To test the RV RF strain for its tolerance for peptide insertions, we constructed a reverse genetics system. NSP3 was C-terminally tagged with SARS-CoV-2 spike peptides of up to 193 amino acids in length. With a T2A-separated 193 amino acid tag on NSP3, there was no significant effect on the viral rescue efficiency, endpoint titer, and replication kinetics. Tagged NSP3 elicited cross-reactivity with SARS-CoV-2 spike antibodies in ELISA. We highlight the potential for development of RV vaccine vectors targeting multiple enteric pathogens simultaneously.

Rotavirus VP6: involvement in immunogenicity, adjuvant activity, and use as a vector for heterologous peptides, drug delivery, and production of nano-biomaterials

The first-generation, live attenuated rotavirus (RV) vaccines, such as RotaTeq and Rotarix, were successful in reducing the number of RV-induced acute gastroenteritis (AGE) and child deaths globally. However, the low efficacy of these first-generation oral vaccines, coupled with safety concerns, required development of improved RV vaccines. The highly conserved structural protein VP6 is highly immunogenic, and it can generate self-assembled nano-sized structures, including tubes and spheres (virus-like particles; VLPs). Amongst the RV proteins, only VP6 shows these features. Interestingly, VP6-assembled structures, in addition to being highly immunogenic, have several other useful characteristics that could allow them to be used as adjuvants, immunological carriers, and drug-delivery vehicles as well as acting a scaffold for production of valuable nano-biomaterials. This review provides an overview of the self-assembled nano-sized structures of VP6-tubes/VLPs and their various functions.

Leveraging Beneficial Off-Target Effects of Live-Attenuated Rotavirus Vaccines

Following the introduction of live-attenuated rotavirus vaccines in many countries, a notable reduction in deaths and hospitalisations associated with diarrhoea in children <5 years of age has been reported. There is growing evidence to suggest that live-attenuated vaccines also provide protection against other infections beyond the vaccine-targeted pathogens. These so called off-target effects of vaccination have been associated with the tuberculosis vaccine Bacille Calmette Guérin (BCG), measles, oral polio and recently salmonella vaccines, and are thought to be mediated by modified innate and possibly adaptive immunity. Indeed, rotavirus vaccines have been reported to provide greater than expected reductions in acute gastroenteritis caused by other enteropathogens, that have mostly been attributed to herd protection and prior underestimation of rotavirus disease. Whether rotavirus vaccines also alter the immune system to reduce non targeted gastrointestinal infections has not been studied directly. Here we review the current understanding of the mechanisms underlying off-target effects of vaccines and propose a mechanism by which the live-attenuated neonatal rotavirus vaccine, RV3-BB, could promote protection beyond the targeted pathogen. Finally, we consider how vaccine developers may leverage these properties to improve health outcomes in children, particularly those in low-income countries where disease burden and mortality is disproportionately high relative to developed countries.

Understanding Rotavirus Vaccine Efficacy and Effectiveness in Countries with High Child Mortality

Rotavirus claims thousands of lives of children globally every year with a disproportionately high burden in low- and lower-middle income countries where access to health care is limited. Oral, live-attenuated rotavirus vaccines have been evaluated in multiple settings in both low- and high-income populations and have been shown to be safe and efficacious. However, the vaccine efficacy observed in low-income settings with high rotavirus and diarrheal mortality was significantly lower than that seen in high-income populations where rotavirus mortality is less common. Rotavirus vaccines have been introduced and rolled out in more than 112 countries, providing the opportunity to assess effectiveness of the vaccines in these different settings. We provide an overview of the efficacy, effectiveness, and impact of rotavirus vaccines, focusing on high-mortality settings and identify the knowledge gaps for future research. Despite lower efficacy, rotavirus vaccines substantially reduce diarrheal disease and mortality and are cost-effective in countries with high burden. Continued evaluation of the effectiveness, impact, and cost–benefit of rotavirus vaccines, especially the new candidates that have been recently approved for global use, is a key factor for new vaccine introductions in countries, or for a switch of vaccine product in countries with limited resources.

Review of Over 15 Years Postmarketing Safety Surveillance Spontaneous Data for the Human Rotavirus Vaccine (Rotarix) on Intussusception

Introduction

Rotavirus (RV) is the most common cause of acute gastroenteritis in children <5 years of age worldwide, and vaccination reduces the disease burden. Evidence from postmarketing surveillance studies suggested an increased risk of intussusception (IS) in infants post-RV vaccination. An overall positive benefit–risk balance for the human RV vaccine (HRV) Rotarix (GlaxoSmithKline [GSK], Belgium) has been established and recent findings indicate an indirect effect of reduced IS over the long term.

Objective

The aim of this study was to discuss spontaneous data from the GSK worldwide safety database on IS post-Rotarix administration.

Methods

The database was reviewed for all spontaneous IS cases from 2004 to 2020. Additionally, an observed versus expected (O/E) analysis was done for adverse events attributed to IS. Data were reviewed as overall worldwide and stratified by region (Europe/USA/Japan) and dose.

Results

A male predominance of IS patients was observed, consistent with earlier reports. The most frequently reported events in confirmed IS cases (Brighton Collaboration Working Group [BCWG] level 1) with time to onset ≤ 30 days post-vaccination were vomiting (55.8%), haematochezia (47.2%), and crying (21.1%). The observations from the IS spontaneous cases review and results of the O/E analysis are consistent with the known IS safety profile of RV vaccines: a transient increased incidence of IS post-vaccination (primarily in Europe/Japan/worldwide), mostly within 7 days postdose 1.

Conclusion

Since the outcomes of early IS management are favourable over delayed management, healthcare professionals should inform parents about the importance of seeking immediate medical advice in case of unusual behaviour of the vaccinated infant. GSK continues to monitor the IS risk post-Rotarix administration through routine pharmacovigilance activities.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01141-4.

Rotavirus (RV) is the most common cause of acute gastroenteritis and a major cause of death in young children worldwide. Vaccination has been instrumental in reducing the impact of RV disease. Real-world evidence suggests an increased risk of intussusception (an infrequent type of bowel obstruction) in infants following RV vaccination. We reviewed IS cases reported spontaneously worldwide in children following a two-dose vaccination with the human RV vaccine (Rotarix, GlaxoSmithKline [GSK]) since its launch in 2004. We observed that (1) IS occurred more frequently 7 days after the first dose and, to a lesser extent, after the second dose; (2) boys were more frequently affected than girls (56.3%); (3) of 862 confirmed reported cases, 557 required hospitalisation; and (4) surgical intervention was required for 294 of 557 hospitalised cases. We used statistical analysis to assess whether the number of cases observed would be higher or lower than the natural occurrence of IS (irrespective of vaccination). These results were in line with the known RV vaccine safety profile. It is important to constantly monitor the real-world safety profile of RV vaccines in the postmarketing setting. Since the outcomes of early management of IS are favourable compared with delayed management, healthcare professionals should inform parents to seek immediate medical advice if they observe unusual behaviour in their vaccinated child. In conclusion, our analyses on data of a large patient pool for this rare event reinforce the favourable safety profile of human RV vaccine and the benefits of vaccination in young children.