Fulfilling the promise of rotavirus vaccines: how far have we come since licensure?

Left out in the cold - inequity in infectious disease control due to cold chain disparity

Vaccines and diagnostic tools stand out as among the most influential advancements in public health, credited with averting an estimated 6 million deaths annually and substantially alleviating the burden of infectious disease. Despite this progress, the global imperative to prevent, detect, and combat infectious disease persists. Regrettably, hundreds of thousands of lives are still lost due to inadequate access to vaccines and diagnostics. A critical obstacle in accessibility lies in the requirement of reliable cold chain for their transportation and storage, a resource that remains inadequate in many regions, particularly in the developing world. Various factors, including socio-economic disparities, biological complexities, and manufacturing processes, exert significant influence on the availability and integrity of vaccines and diagnostic materials. This review aims to explore the multifaceted issue of inequality in access to disease control tools, examining the vulnerabilities of vaccines and diagnostics while also investigating recent advancements that offer promising solutions to improve thermal stability.

Significant abundance of bacterial flagellin and expression of its surface localized receptor toll-like receptor 5 and cytokine interleukin-22 in South African infants with poor oral rotavirus vaccine take

Bacterial flagellin, a potent intestinal innate immune activator, prevents murine rotavirus (RV) infection independent of adaptive immunity and interferons. The flagellin-induced immunity is mediated by Toll-like receptor (TLR5) and Nod-like receptor C4 (NLRC4), which elicit the production of interleukins 22 (IL-22) and IL-18, respectively. Here, we assessed whether a high abundance of flagellin at the time of vaccination would negatively affect the oral RV vaccine take. Fecal samples were collected from infants a week after first dose of Rotarix vaccination to establish vaccine shedders (n = 50) and non-shedders (n = 44). The abundance of flagellin and expression of flagellin-encoding fliC, TLR5 and NLRC4, IL-22 and IL-18 genes was determined by qPCR. There were no differences in the abundance of flagellin between vaccine shedders and non-shedders (p = 0.15). However, the expression of FliC was increased 7.5-fold in non-shedders versus shedders (p = 0.001). Similarly, TLR5 (p = 0.045), and not NLRC4 (p = 0.507,) was significantly expressed in non-shedders versus shedders. The expression of IL-22 (p = 0.054), and not IL-18 dependent NLRC4 (p = 0.650), was increased 3.4-fold in non-shedders versus shedders. Collectively, our observations suggest a possible negative impact of the abundance of viable flagellated bacteria at the time of vaccination on the replication and therefore the performance of RV vaccines.

Protocol for detection of pathogenic enteric RNA viruses by regular monitoring of environmental samples from wastewater treatment plants using droplet digital PCR

BACKGROUND

The present comprehensive protocol is focused on the detection of pathogenic enteric RNA viruses, explicitly focusing on norovirus genogroup Ⅱ (GⅡ), astrovirus, rotavirus, Aichi virus, sapovirus, hepatitis A and E viruses in wastewater treatment plants through droplet digital PCR (ddPCR). Enteric viruses are of significant public health concern, as they are the leading cause of diseases like gastroenteritis. Regular monitoring of environmental samples, particularly from wastewater treatment plants, is crucial for early detection and control of these viruses. This research aims to improve the understanding of the prevalence and dynamics of enteric viruses in urban India and will serve as a model for similar studies in other regions. Our protocol's objective is to establish a novel ddPCR-based methodology for the detection and molecular characterization of enteric viruses present in wastewater samples sourced from Bhopal, India. Our assay is capable of accurately quantifying virus concentrations without standard curves, minimizing extensive optimization, and enhancing sensitivity and precision, especially for low-abundance targets.

METHODS

The study involves fortnightly collecting and analyzing samples from nine wastewater treatment plants over two years, ensuring comprehensive coverage and consistent data. Our study innovatively applies ddPCR to simultaneously detect and quantify enteric viruses in wastewater, a more advanced technique. Additionally, we will employ next-generation sequencing for detailed viral genome identification in samples tested positive for pathogenic viruses.

CONCLUSION

This study will aid in understanding these viruses' genetic diversity and mutation rates, which is crucial for developing tailored intervention strategies. The findings will be instrumental in shaping public health responses and improving epidemiological surveillance, especially in localities heaving sewage networks.

Rotavirus in developing countries: molecular diversity, epidemiological insights, and strategies for effective vaccination

Rotavirus (RV) causes the loss of numerous children's lives worldwide each year, and this burden is particularly heavy in low- and lower-middle-income countries where access to healthcare is limited. RV epidemiology exhibits a diverse range of genotypes, which can vary in prevalence and impact across different regions. The human genotypes that are most commonly recognized are G1P[8], G2P[4], G3P[8], G4P[8], G8P[8], G9P[8], and G12P[8]. The diversity of rotavirus genotypes presents a challenge in understanding its global distribution and developing effective vaccines. Oral, live-attenuated rotavirus vaccines have undergone evaluation in various contexts, encompassing both low-income and high-income populations, demonstrating their safety and effectiveness. Rotavirus vaccines have been introduced and implemented in over 120 countries, offering an opportunity to assess their effectiveness in diverse settings. However, these vaccines were less effective in areas with more rotavirus-related deaths and lower economic status compared to wealthier regions with fewer rotavirus-related deaths. Despite their lower efficacy, rotavirus vaccines significantly decrease the occurrence of diarrheal diseases and related mortality. They also prove to be cost-effective in regions with a high burden of such diseases. Regularly evaluating the impact, influence, and cost-effectiveness of rotavirus vaccines, especially the newly approved ones for worldwide use, is essential for deciding if these vaccines should be introduced in countries. This is especially important in places with limited resources to determine if a switch to a different vaccine is necessary. Future research in rotavirus epidemiology should focus on a comprehensive understanding of genotype diversity and its implications for vaccine effectiveness. It is crucial to monitor shifts in genotype prevalence and their association with disease severity, especially in high-risk populations. Policymakers should invest in robust surveillance systems to monitor rotavirus genotypes. This data can guide vaccine development and public health interventions. International collaboration and data sharing are vital to understand genotype diversity on a global scale and facilitate the development of more effective vaccines.

Rotavirus and bacterial diarrhoea among children in Ile-Ife, Nigeria: Burden, risk factors and seasonality

BACKGROUND

Diarrhoea is a leading cause of death among under-five children globally, with sub-Saharan Africa alone accounting for 1/3 episodes yearly. Viruses, bacteria and parasites may cause diarrhoea. Rotavirus is the most common viral aetiology of diarrhoea in children less than five years globally. In Nigeria, there is scarce data on the prevalence/importance, burden, clinical/risk factors and seasonality of rotavirus and bacteria and this study aims to determine the role of rotavirus and bacteria on diarrhoea cases in children less than five years in Ile-Ife, Nigeria.

METHODS

Socio-demographic data, environmental/risk factors and diarrhoiec stool samples were collected from children less than five years presenting with acute diarrhoea. Rotavirus was identified using ELISA. Bacteria pathogens were detected using cultural technique and typed using PCR. Diarrhoeagenic E. coli (DEC) isolates were subjected to antimicrobial susceptibility testing. Pathogen positive and negative samples were compared in terms of gender, age-group, seasonal distribution, and clinical/risk factors using chi-square with two-tailed significance. SPSS version 20.0.1 for Windows was used for statistical analysis.

RESULTS

At least one pathogen was detected from 63 (60.6%) children having gastroenteritis while 28 (44.4%) had multiple infections. Rotavirus was the most detected pathogen. Prevalence of rotavirus mono-infection was 22%, multiple infection with bacteria was 45%. Mono-infection prevalence of DEC, Shigella spp., and Salmonella spp. were 5.8% (6/104), 5.8% (6/104), and 2.9% (3/104) and co-infection with RVA were 23.1% (24/104), 21.2% (22/104) and 10.6% (11/104) respectively. All rotaviral infections were observed in the dry season. The pathotypes of DEC detected were STEC and EAEC. Parent earnings and mid-upper arm circumference measurement have statistical correlation with diarrhoea (p = 0.034; 0.035 respectively).

CONCLUSION

In this study, rotavirus was more prevalent than bacteria and occurred only in the dry season. Among bacteria aetiologies, DEC was the most common detected. Differences in seasonal peaks of rotavirus and DEC could be employed in diarrhoea management in Nigeria and other tropical countries to ensure optimal limited resources usage in preventing diarrhoea transmission and reducing indiscriminate use of antibiotics.

Circulation of Vaccine-derived Rotavirus G1P[8] in a Vulnerable Child Cohort in Rio de Janeiro

BACKGROUND

The expansion of rotavirus (RV) immunization in several countries reduced the burden of acute diarrheal disease (ADD) and diarrhea-associated mortality. Although community transmission of live attenuated monovalent rotavirus vaccine (G1P[8] RV1) virus has been demonstrated in children and household contacts, fecal shedding of these strains in neonates and infants under six weeks of age has never been demonstrated. The objective of the study was to assess ADD and rotavirus vaccine strain shedding before and after immunization through 24 months of age.

METHODS

This was a prospective cohort study in a low-resource community in which stool samples were collected from neonates from 15 to 45 days of age every 2 weeks, after both doses of G1P[8] RV1, and in subsequent ADD episodes until 2 years of age. RV was detected and genotyped in stool samples by RT-PCR.

RESULTS

We enrolled 242 participants who were followed for an average of 23 months. The specific prevalence of G1P[8] RV1 virus was 3.3% in neonates and infants less than six weeks of age, 50% after the first dose, and 25.6% after the second dose. Among the 70 participants with ADD, G1P[8] RV1 virus was identified in only one participant (1.4% prevalence).

CONCLUSIONS

In vaccinated children, there were no breakthrough infections with G1P[8] RV1 and ADD was rare supporting high vaccine effectiveness. We observed G1P[8] RV1 virus shedding among neonates and infants before the first vaccine dose, providing evidence of transmission of the vaccine strain from immunized children to those who are not yet vaccinated.

Molecular epidemiology, genetic diversity, and vaccine availability of viral acute gastroenteritis in the middle East and North Africa (MENA) region

Acute gastroenteritis is the cause of considerable mortality and morbidity worldwide, particularly among children under five years in underdeveloped countries. Most acute gastroenteritis (AGE) cases are attributed to viral etiologies, including rotavirus, norovirus, adenovirus, astrovirus, and sapovirus. This paper aimed to determine the prevalence rate of different viral etiologies of AGE in the Middle East and North Africa (MENA) region. Moreover, this paper explored rotavirus phylogenetic relatedness, compared VP7 and VP4 antigenic regions of rotavirus with vaccine strains, and explored the availability of vaccines in the MENA region. The literature search identified 160 studies from 18 countries from 1980 to 2019. The overall prevalence of rotavirus, norovirus, adenovirus, astrovirus, and sapovirus were 29.8 %, 13.9 %, 6.3 %, 3.5 %, and 3.2 % of tested samples, respectively. The most common rotavirus genotype combinations in the MENA region were G1P[8], G9P[9], and G2P[4], whereas GII.4 was the predominant norovirus genotype all of which were reported in almost all the studies with genotyping data. The comparison of VP7 and VP4 between circulating rotavirus in the MENA region and vaccine strains has revealed discrete divergent regions, including the neutralizing epitopes. Rotavirus vaccine was introduced to most of the countries of the MENA region; however, only a few studies have assessed the effectiveness of vaccine introduction. This paper provides a comprehensive update on the prevalence of the different viral agents of AGE in the MENA region.

Mucosal COVID-19 vaccines: Risks, benefits and control of the pandemic

Based on mucosal immunization to promote both mucosal and systemic immune responses, next-generation coronavirus disease 2019 (COVID-19) vaccines would be administered intranasally or orally. The goal of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines is to provide adequate immune protection and avoid severe disease and death. Mucosal vaccine candidates for COVID-19 including vector vaccines, recombinant subunit vaccines and live attenuated vaccines are under development. Furthermore, subunit protein vac-cines and virus-vectored vaccines have made substantial progress in preclinical and clinical settings, resulting in SARS-CoV-2 intranasal vaccines based on the previously successfully used nasal vaccines. Additional to their ability to trigger stable, protective immune responses at the sites of pathogenic infection, the development of 'specific' mucosal vaccines targeting coronavirus antigens could be an excellent option for preventing future pandemics. However, their efficacy and safety should be confirmed.

Infection with adenovirus, rotavirus, and coinfection among hospitalized children with gastroenteritis in an Egyptian university hospital

Acute gastroenteritis is the main cause of mortality and morbidity in children worldwide. Studies stated that rotavirus and human adenovirus (HAdV) are common causes of nonbacterial gastroenteritis in children aged 0-5 years. The aim of this study was to determine the prevalence and the distribution of rotavirus, HAdV, and coinfections among hospitalized children with gastroenteritis below 7 years old and determine the prevalence of enteric HAdV among all HAdV gastroenteritis. The study was conducted on 150 children below 7 years old. Antigen detection for rotavirus and HAdV by ELISA and determination of enteric HAdV (serotype 40 and 41) by nested PCR and restriction endonucleases study were performed. Detection of rotavirus and HAdV antigens in 150 stool specimens from patients with gastroenteritis were 58% (87), 6.7% (10), and 8% (12) positive for rotavirus, HAdV, and coinfection, respectively. Out of 22 HAdV antigen-positive cases, 15 cases were positive by PCR for enteric HAdV, with the prevalence rate of enteric HAdV gastroenteritis among all HAdV gastroenteritis cases of 68%, a serotyping study by PCR detected serotype 40 in 46.7% of cases (7/15) and serotype 41 in 53.3% of cases (8/15) with no statistically significant difference between them. The study confirmed that rotavirus and HAdV are prevalent etiological agents of diarrhea in children below the school-age group, highlighting the necessity of the rotavirus vaccine in addition to the obligatory schedule of vaccines in Egypt. Also, it determined that the enteric HAdV gastroenteritis prevalence rate was 68% among all HAdV gastroenteritis.

Vaccine Effectiveness Against Life-Threatening Influenza Illness in US Children

BACKGROUND

Predominance of 2 antigenically drifted influenza viruses during the 2019-2020 season offered an opportunity to assess vaccine effectiveness against life-threatening pediatric influenza disease from vaccine-mismatched viruses in the United States.

METHODS

We enrolled children aged <18 years admitted to the intensive care unit with acute respiratory infection across 17 hospitals. Respiratory specimens were tested using reverse-transcription polymerase chain reaction for influenza viruses and sequenced. Using a test-negative design, we estimated vaccine effectiveness comparing odds of vaccination in test-positive case patients vs test-negative controls, stratifying by age, virus type, and severity. Life-threating influenza included death or invasive mechanical ventilation, vasopressors, cardiopulmonary resuscitation, dialysis, or extracorporeal membrane oxygenation.

RESULTS

We enrolled 159 critically ill influenza case-patients (70% ≤8 years; 51% A/H1N1pdm09 and 25% B-Victoria viruses) and 132 controls (69% were aged ≤8 years). Among 56 sequenced A/H1N1pdm09 viruses, 29 (52%) were vaccine-mismatched (A/H1N1pdm09/5A+156K) and 23 (41%) were vaccine-matched (A/H1N1pdm09/5A+187A,189E). Among sequenced B-lineage viruses, majority (30 of 31) were vaccine-mismatched. Effectiveness against critical influenza was 63% (95% confidence interval [CI], 38% to 78%) and similar by age. Effectiveness was 75% (95% CI, 49% to 88%) against life-threatening influenza vs 57% (95% CI, 24% to 76%) against non-life-threating influenza. Effectiveness was 78% (95% CI, 41% to 92%) against matched A(H1N1)pdm09 viruses, 47% (95% CI, -21% to 77%) against mismatched A(H1N1)pdm09 viruses, and 75% (95% CI, 37% to 90%) against mismatched B-Victoria viruses.

CONCLUSIONS

During a season when vaccine-mismatched influenza viruses predominated, vaccination was associated with a reduced risk of critical and life-threatening influenza illness in children.

A literature review of severity scores for adults with influenza or community-acquired pneumonia - implications for influenza vaccines and therapeutics

Influenza vaccination and antiviral therapeutics may attenuate disease, decreasing severity of illness in vaccinated and treated persons. Standardized assessment tools, definitions of disease severity, and clinical endpoints would support characterizing the attenuating effects of influenza vaccines and antivirals. We review potential clinical parameters and endpoints that may be useful for ordinal scales evaluating attenuating effects of influenza vaccines and antivirals in hospital-based studies. In studies of influenza and community-acquired pneumonia, common physiologic parameters that predicted outcomes such as mortality, ICU admission, complications, and duration of stay included vital signs (hypotension, tachypnea, fever, hypoxia), laboratory results (blood urea nitrogen, platelets, serum sodium), and radiographic findings of infiltrates or effusions. Ordinal scales based on these parameters may be useful endpoints for evaluating attenuating effects of influenza vaccines and therapeutics. Factors such as clinical and policy relevance, reproducibility, and specificity of measurements should be considered when creating a standardized ordinal scale for assessment.

Differentiating severe and non-severe lower respiratory tract illness in patients hospitalized with influenza: Development of the Influenza Disease Evaluation and Assessment of Severity (IDEAS) scale

BACKGROUND

Experimental studies have shown that vaccination can reduce viral replication to attenuate progression of influenza-associated lower respiratory tract illness (LRTI). However, clinical studies are conflicting, possibly due to use of non-specific outcomes reflecting a mix of large and small airway LRTI lacking specificity for acute lung or organ injury.

METHODS

We developed a global ordinal scale to differentiate large and small airway LRTI in hospitalized adults with influenza using physiologic features and interventions (PFIs): vital signs, laboratory and radiographic findings, and clinical interventions. We reviewed the literature to identify common PFIs across 9 existing scales of pneumonia and sepsis severity. To characterize patients using this scale, we applied the scale to an antiviral clinical trial dataset where these PFIs were measured through routine clinical care in adults hospitalized with influenza-associated LRTI during the 2010-2013 seasons.

RESULTS

We evaluated 12 clinical parameters among 1020 adults; 210 (21%) had laboratory-confirmed influenza, with a median severity score of 4.5 (interquartile range, 2-8). Among influenza cases, median age was 63 years, 20% were hospitalized in the prior 90 days, 50% had chronic obstructive pulmonary disease, and 22% had congestive heart failure. Primary influencers of higher score included pulmonary infiltrates on imaging (48.1%), heart rate ≥110 beats/minute (41.4%), oxygen saturation <93% (47.6%) and respiratory rate >24 breaths/minute (21.0%). Key PFIs distinguishing patients with severity < or ≥8 (upper quartile) included infiltrates (27.1% vs 90.0%), temperature ≥ 39.1°C or <36.0°C (7.1% vs 27.1%), respiratory rate >24 breaths/minute (7.9% vs 47.1%), heart rate ≥110 beats/minute (29.3% vs 65.7%), oxygen saturation <90% (14.3% vs 31.4%), white blood cell count >15,000 (5.0% vs 27.2%), and need for invasive or non-invasive mechanical ventilation (2.1% vs 15.7%).

CONCLUSION

We developed a scale in adults hospitalized with influenza-associated LRTI demonstrating a broad distribution of physiologic severity which may be useful for future studies evaluating the disease attenuating effects of influenza vaccination or other therapeutics.

Diversity of Rotavirus Strains in Children; Results From a Community-Based Study in Nepal

Objective: The objectives of this study were to describe the incidence and genetic diversity of Rotavirus (RV) infection among children up to 3 years of age in a community in Nepal.

Methods: We investigated community-acquired cases of asymptomatic and symptomatic RV infections in children from birth to 36 months of age in a community-based birth cohort in Bhaktapur, Nepal. Monthly surveillance and diarrheal stool samples were collected from 240 children enrolled at birth, of which 238 completed the 3 years of follow-up. Samples were screened for rotavirus by Enzyme Immuno Assay (EIA). All RV screened positives were further genotyped by reverse transcription-polymerase chain reaction for the capsid genes VP7 and VP4.

Results: In total, 5,224 stool samples were collected from 238 children, followed from birth to 36 months of age. Diarrhea occurred in 92.4% (230/238) of all children in the cohort. During the 3 years study period, RV was more frequently seen in children with symptoms (7.6%) than in non-symptomatic children (0.8%). The highest RV detection rate was found in younger children between 3 and 21 months of age. Although rotavirus is known as winter diarrhea, it was detected throughout the year except in August. The highest positivity rate was observed in the months between December and March, with a peak in January. Four common G types were seen: G2 (30%), G1 (29%), G12 (19%), and G9 (16%). The most predominant genotypes seen were G2P[4] (30%), followed by G1P[8] (27.0%), G12P[6] (14.0%), G9P[8] (10%), and remaining were mixed, partial, and untyped.

Conclusion: Our study confirms that rotavirus is a common cause of gastroenteritis in young children in the community. The prevalence and pathogenicity of rotavirus infection differed by age. There was substantial variability in circulating strains in the community samples compared to samples collected from hospitals. This shows the importance of including community-based surveillance systems to monitor the diversity of circulating rotavirus strains in Nepal.

Clinical and molecular epidemiological characterization of rotavirus infections in children under five years old in Shandong province, China

Rotaviruses are important causative agents of acute gastroenteritis in children. In China, rotavirus infection has a prevalence rate of 30% and is therefore considered a serious public health problem. This study was carried out to investigate the clinical and molecular epidemiological characteristics of rotavirus infections in children under 5 years old with acute diarrhea in Shandong province, China. From July 2017 to June 2018, a total of 1211 fecal specimens were tested, and the prevalence of rotavirus infection was 32.12%. The mean age of the infected children was 12.2 ± 10.9 months, and the highest infection rate was observed in children aged 7-12 months, with a rate of 41.64%. G9P[8] (76.61%) was the most prevalent genotype combination, followed by G2P[4] (7.20%), G3P[8] (3.60%), and G9P[4] (2.06%). In addition to diarrhea, vomiting, fever, and dehydration were the most common clinical signs. In general, there was no significant difference in clinical manifestations among different age groups. However, the clinical manifestations differed significantly between vaccinated and unvaccinated children. Vaccinated children showed lower incidence and frequency of vomiting, lower incidence and degree of dehydration, and lower incidence of severe cases than unvaccinated children. These findings suggest that it is necessary to continuously monitor changes in the characteristics of rotavirus infections. Moreover, the introduction of vaccines into the national immunization program to prevent and control rotavirus infection is needed in China.

Thermostable, Dissolvable Buccal Film Rotavirus Vaccine Is Highly Effective in Neonatal Gnotobiotic Pig Challenge Model

Difficulties related to storage and transport of currently available live oral rotavirus vaccines can have detrimental consequences on the efficacy of the vaccines. Thus, there is a great need for thermostable vaccines that can eliminate the necessity for cold chain storage or reconstitution before administration. In this study, we developed a dissolvable oral polymeric film comprised of a live attenuated thermostable tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV) powder and antacid (CaCO3). Immunogenicity and protective efficacy of the vaccine after buccal delivery was evaluated in the gnotobiotic pig model of human rotavirus (HRV) infection and diarrhea. Two doses of the vaccine were highly immunogenic and conferred strong protection against virus shedding and diarrhea upon challenge with a high dose of a virulent G1 HRV in gnotobiotic pigs. Those pigs vaccinated with the preserved film vaccine had significantly delayed onset of diarrhea; reduced duration and area under the curve of diarrhea; delayed onset of fecal virus shedding; and reduced duration and peak of fecal virus shedding titers compared to pigs in both the placebo and the reconstituted liquid oral RRV-TV vaccine groups. Associated with the strong protection, high titers of serum virus neutralization antibodies against each of the four RRV-TV mono-reassortants and G1 HRV-specific serum IgA and IgG antibodies, as well as intestinal IgA antibodies, were induced by the preserved film vaccine. These results demonstrated the effectiveness of our thermostable buccal film rotavirus vaccine and warrant further investigation into the promise of the novel technology in addressing drawbacks of the current live oral HRV vaccines.

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.

The impact of publicly funded rotavirus immunization programs on Canadian children

Background

In 2008, the National Advisory Committee on Immunization recommended routine rotavirus immunizations in healthy Canadian infants. Over the following seven years, eight provinces and two territories introduced the rotavirus vaccine into their publicly funded immunization programs.

Objective

Assess the burden of rotavirus infections before and after implementation of publicly funded immunization programs.

Methods

We analyzed laboratory-confirmed community cases of rotavirus reported to the National Enteric Surveillance Program and hospitalizations of children younger than three years old from 2007 to 2017 with rotavirus diagnosis-specific ICD-10 codes. Rates of illness were calculated for each province for the two years prior to and after implementation of public funding of the vaccine. The year of implementation was not included to accommodate the uptake period of the vaccine. Age-specific rates were assessed in jurisdictions where five years of data were available the year after the vaccine was publicly funded. The pre-post and difference-in-difference (DID) methodologies were applied to hospital discharge data to evaluate changes between the funding and non-funding jurisdictions.

Results

Community cases of laboratory-confirmed rotavirus infection reported to the National Enteric Surveillance Program declined by 54% between 2010 and 2017. Rates of hospital discharges decreased significantly among children in six provinces after the adoption of the rotavirus vaccine. Hospital discharge rates in Alberta, Manitoba, Ontario and Prince Edward Island dropped between 53% and 71%, and by 75% for British Columbia and Saskatchewan.

Conclusion

Public funding of the rotavirus vaccine appeared to lead to significant reductions in laboratory-confirmed rotavirus cases reported to the National Enteric Surveillance Program and in the rates of rotavirus gastroenteritis-related hospital discharges.

Impact of Rotavirus Vaccination Varies by Level of Access to Piped Water and Sewerage: An Analysis of Childhood Clinic Visits for Diarrhea in Peru, 2005-2015

BACKGROUND

We conducted a national impact evaluation of routine rotavirus vaccination on childhood diarrhea in Peru, accounting for potential modifying factors.

METHODS

We utilized a dataset compiled from Peruvian governmental sources to fit negative binomial models investigating the impact of rotavirus vaccination, piped water access, sewerage access and poverty on the rate of diarrhea clinic visits in children under 5 years old in 194 Peruvian provinces. We considered the interaction between these factors to assess whether water access, sanitation access, or poverty modified the association between ongoing rotavirus vaccination and childhood diarrhea clinic visits. We compared the "pre-vaccine" (2005-2009) and "post-vaccine" (2010-2015) eras.

RESULTS

The rate of childhood diarrhea clinic visits was 7% [95% confidence interval (CI): 3%-10%] lower in the post-vaccine era compared with the pre-vaccine era, controlling for long-term trend and El Niño seasons. No impact of rotavirus vaccination was identified in provinces with the lowest access to piped water (when <40% of province households had piped water) or in the lowest category of sewerage (when <17% of province households had a sewerage connection). Accounting for long-term and El Niño trends, the rate of childhood diarrhea clinic visits was lower in the post-vaccine era by 7% (95% CI: 2%-12%), 13% (95% CI: 7%-19%) and 15% (95% CI: 10%-20%) in the second, third and fourth (highest) quartiles of piped water access, respectively (compared with the pre-vaccine era); results for sewerage access were similar.

CONCLUSION

Improved water/sanitation may operate synergistically with rotavirus vaccination to reduce childhood clinic visits for diarrhea in Peru.

Impact of Routine Rotavirus Vaccination in Germany: Evaluation Five Years After Its Introduction

BACKGROUND

Routine rotavirus (RV)-vaccination is recommended in Germany since August 2013. Five years later, we evaluated the recommendation by examining vaccine uptake and the impact on RV-gastroenteritis (RVGE) burden in all age groups and on intussusceptions in infants.

METHODS

We estimated RV-vaccine uptake in the 2014-2018 birth cohorts using statutory health insurance prescription data. For impact assessment, we analyzed RVGE-surveillance data of the German infectious diseases notification system. We compared age-specific RVGE-incidences of different severity between pre-vaccination (2005/06-2007/08) and routine vaccination period (2013/14-2017/18) calculating incidence rate ratios (IRR) using Poisson regression. To determine the effect on intussusception, we used hospital discharge data (2006-2017) and compared incidences between pre-vaccination and routine vaccination period using Poisson regression.

RESULTS

Vaccination coverage increased from 59% (2014) to 80% (2018). Incidences of RVGE-outpatient cases, RVGE-hospitalization and nosocomial RVGE among <5-year-olds decreased by 74% (IRR = 0.26; 95% CI: 0.26-0.27), 70% (IRR = 0.30; 95% CI: 0.30-0.31) and 70% (IRR = 0.30; 95% CI: 0.30-0.31), respectively. Incidence of RVGE-outpatient cases in age groups ineligible for RV-vaccination decreased by 38% (IRR 0.62; 95% CI: 0.61-0.63). Compared with the pre-vaccination period, incidence of intussusception in the first year of life decreased by 28% (IRR = 0.73; 95% CI: 0.68-0.79) while at age of the first vaccine-dose (7th-12th week of age) increase in incidence of intussusception was non-significant (IRR = 1.29; 95% CI: 0.93-1.78).

CONCLUSIONS

Routine RV-vaccination is well accepted in Germany. Since implementation of routine RV-vaccination, RVGE significantly decreased in <5-year-olds and in non-vaccinated older age groups through herd protection. The decline of intussusceptions in the first life year suggests a potential vaccination-associated protection against gastrointestinal infections that might trigger intussusceptions. These encouraging results should be communicated to doctors and parents for further improvement of vaccine uptake and protection of more infants.

Parenterally Administered P24-VP8* Nanoparticle Vaccine Conferred Strong Protection against Rotavirus Diarrhea and Virus Shedding in Gnotobiotic Pigs

Current live rotavirus vaccines are costly with increased risk of intussusception due to vaccine replication in the gut of vaccinated children. New vaccines with improved safety and cost-effectiveness are needed. In this study, we assessed the immunogenicity and protective efficacy of a novel P24-VP8* nanoparticle vaccine using the gnotobiotic (Gn) pig model of human rotavirus infection and disease. Three doses of P24-VP8* (200 μg/dose) intramuscular vaccine with Al(OH)₃ adjuvant (600 μg) conferred significant protection against infection and diarrhea after challenge with virulent Wa strain rotavirus. This was indicated by the significant reduction in the mean duration of diarrhea, virus shedding in feces, and significantly lower fecal cumulative consistency scores in post-challenge day (PCD) 1-7 among vaccinated pigs compared to the mock immunized controls. The P24-VP8* vaccine was highly immunogenic in Gn pigs. It induced strong VP8*-specific serum IgG and Wa-specific virus-neutralizing antibody responses from post-inoculation day 21 to PCD 7, but did not induce serum or intestinal IgA antibody responses or a strong effector T cell response, which are consistent with the immunization route, the adjuvant used, and the nature of the non-replicating vaccine. The findings are highly translatable and thus will facilitate clinical trials of the P24-VP8* nanoparticle vaccine.

Quantifying the Impact of Natural Immunity on Rotavirus Vaccine Efficacy Estimates: A Clinical Trial in Dhaka, Bangladesh (PROVIDE) and a Simulation Study

Background

The low efficacy of rotavirus vaccines in clinical trials performed in low-resource settings may be partially explained by acquired immunity from natural exposure, especially in settings with high disease incidence.

Methods

In a clinical trial of monovalent rotavirus vaccine in Bangladesh, we compared the original per-protocol efficacy estimate to efficacy derived from a recurrent events survival model in which children were considered naturally exposed and potentially immune after their first rotavirus diarrhea (RVD) episode. We then simulated trial cohorts to estimate the expected impact of prior exposure on efficacy estimates for varying rotavirus incidence rates and vaccine efficacies.

Results

Accounting for natural immunity increased the per-protocol vaccine efficacy estimate against severe RVD from 63.1% (95% confidence interval [CI], 33.0%-79.7%) to 70.2% (95% CI, 44.5%-84.0%) in the postvaccination period, and original year 2 efficacy was underestimated by 14%. The simulations demonstrated that this expected impact increases linearly with RVD incidence, will be greatest for vaccine efficacies near 50%, and can reach 20% in settings with high incidence and low efficacy.

Conclusions

High rotavirus incidence leads to predictably lower vaccine efficacy estimates due to the acquisition of natural immunity in unvaccinated children, and this phenomenon should be considered when comparing efficacy estimates across settings.

Clinical Trials Registration

NCT01375647.

Introduction of rotavirus vaccination in a Swedish region: assessing parental decision-making, obtained vaccination coverage and resulting hospital admissions

AIM

This study evaluated the introduction of rotavirus vaccination in Jönköping County, Sweden, starting in 2014. This project explored the parental factors that influenced the decision to vaccinate and studied the obtained vaccination coverage and its potential influence on hospital admissions due to acute gastroenteritis.

METHODS

This was a descriptive, cross-sectional study based on a study-specific questionnaire (n = 356) and regional statistical data on vaccination coverage and hospital admissions in Jönköping County, Sweden.

RESULTS

Central aspects when deciding on vaccination were vaccine efficacy and safety, that the vaccine was offered to all children, and recommended by healthcare professionals. One in five parents expressed uncertainty about whether they had sufficient information to make a decision. However, the rotavirus vaccination coverage was elevated from 76.1% to 81.0% and the hospital admissions due to acute gastroenteritis decreased by approximately 60%.

CONCLUSION

The results highlight the necessity for Child Health Services to have solid knowledge regarding vaccinations, to understand individual parental issues and to support uncertain parents. The high vaccination coverage achieved is an indication of the trust in healthcare professionals and is considered to be a major contributing factor to the substantial reduction of hospital admissions due to acute gastroenteritis.

Development of T cell immunity to norovirus and rotavirus in children under five years of age

Most of the research effort to understand protective immunity against norovirus (NoV) has focused on humoral immunity, whereas immunity against another major pediatric enteric virus, rotavirus (RV), has been studied more thoroughly. The aim of this study was to investigate development of cell-mediated immunity to NoV in early childhood. Immune responses to NoV GI.3 and GII.4 virus-like particles and RV VP6 were determined in longitudinal blood samples of 10 healthy children from three months to four years of age. Serum IgG antibodies were measured using enzyme-linked immunosorbent assay and production of interferon-gamma by peripheral blood T cells was analyzed by enzyme-linked immunospot assay. NoV-specific T cells were detected in eight of 10 children by the age of four, with some individual variation. T cell responses to NoV GII.4 were higher than those to GI.3, but these responses were generally lower than responses to RV VP6. In contrast to NoV-specific antibodies, T cell responses were transient in nature. No correlation between cell-mediated and antibody responses was observed. NoV exposure induces vigorous T cell responses in children under five years of age, similar to RV. A role of T cells in protection from NoV infection in early childhood warrants further investigation.

Introducing rotavirus vaccine to the Palestinian territories: the role of public-private partnerships

BACKGROUND

Introducing childhood immunization poses challenges in environments of societal fragility. The Palestinian territories (Pt) are considered 'fragile' because of their lack of political, economic and territorial sovereignty. Poverty is rife, infant mortality high, and diseases associated with overcrowding widespread. Under these circumstances the Rostropovich Vishneskaya Foundation (RVF) has assembled a network of public and private stakeholders to introduce a country-wide rotavirus immunization program.

METHODS

The incidence of diarrhea was determined for 18 months before and 18 months after the introduction of rotavirus vaccine among all children younger than 5 years presenting to outpatient clinics in Gaza with three or more loose stools per day. Simultaneously the prevalence of rotavirus was established by rotavirus antigen detection in stool samples collected from children younger than 3 years at Caritas Baby Hospital in Bethlehem during the corresponding time periods.

RESULTS

Within 12 months 97.4% immunization coverage was achieved. The incidence of diarrhea dropped by 32.2%, while the prevalence of rotavirus in stool samples decreased by 64.6% throughout the following year.

CONCLUSION

In environments of economic or political instability private-public partnerships for the introduction of comprehensive vaccination programs can work based on close collaboration, shared vision, flexibility and inter-organizational trust.

T Lymphocytes as Measurable Targets of Protection and Vaccination Against Viral Disorders

Continuous epidemiological surveillance of existing and emerging viruses and their associated disorders is gaining importance in light of their abilities to cause unpredictable outbreaks as a result of increased travel and vaccination choices by steadily growing and aging populations. Close surveillance of outbreaks and herd immunity are also at the forefront, even in industrialized countries, where previously eradicated viruses are now at risk of re-emergence due to instances of strain recombination, contractions in viral vector geographies, and from their potential use as agents of bioterrorism. There is a great need for the rational design of current and future vaccines targeting viruses, with a strong focus on vaccine targeting of adaptive immune effector memory T cells as the gold standard of immunity conferring long-lived protection against a wide variety of pathogens and malignancies. Here, we review viruses that have historically caused large outbreaks and severe lethal disorders, including respiratory, gastric, skin, hepatic, neurologic, and hemorrhagic fevers. To observe trends in vaccinology against these viral disorders, we describe viral genetic, replication, transmission, and tropism, host-immune evasion strategies, and the epidemiology and health risks of their associated syndromes. We focus on immunity generated against both natural infection and vaccination, where a steady shift in conferred vaccination immunogenicity is observed from quantifying activated and proliferating, long-lived effector memory T cell subsets, as the prominent biomarkers of long-term immunity against viruses and their associated disorders causing high morbidity and mortality rates.

Circulating rotavirus G and P strains post rotavirus vaccination in Eastern Mediterranean Region

OBJECTIVE

To detect changes in circulating strains of rotavirus in the Eastern Mediterranean Region post rotavirus immunization drive.

METHODS

We searched MEDLINE, PubMed, ScienceDirect, and the Cochrane Library and specific database website (Nutrition and Food Sciences) for relevant articles. Our search included websites of a number of relevant organizations in addition to gray literature search. Of the 2198 articles found, we included only 35 studies after excluding irrelevant, ineligible, duplicated, and very low-quality papers.

RESULTS

Thirty pre-vaccination studies reported frequent rotavirus strains among children below 5 years of age. G1P[8] has been identified as the most dominant type prior to vaccination in Eastern Mediterranean Region (EMR) countries. Five post-vaccination studies conducted in 3 countries (Saudi Arabia, Morocco, and Yemen) illustrated that G1P[8] is the most prevalent strain in Saudi Arabia, and the incidence of G2P[4] has increased from 21.6% to 33.3%. In Yemen, G1P[4] is the most prevalent strain (87.5%), followed by G9P[8] (57%) and G1P[8] (18.5%). Furthermore, in Yemen, G9P[8] were the most prevalent strains accounting to 57% and 14% in G9P[4], post vaccination. Finally, in Morocco, G1P[8] was not reported 3 years post vaccination; however, incidence of G9P[8] was reported at 67% and G2P[4] at 33%.

CONCLUSIONS

Rotavirus circulating strain prevalence in EMR countries has changed post vaccination, and G9P[8], G2P[4], and G9P[4] have become more dominant. Proportion of rotavirus strains in these countries after vaccination has significantly reduced. There is an increase in circulating strain G2P[4] in the post-vaccination period, which needs further monitoring.

Rotavirus Vaccination and the Global Burden of Rotavirus Diarrhea Among Children Younger Than 5 Years

IMPORTANCE

Rotavirus infection is the global leading cause of diarrhea-associated morbidity and mortality among children younger than 5 years.

OBJECTIVES

To examine the extent of rotavirus infection among children younger than 5 years by country and the number of deaths averted because of the rotavirus vaccine.

DESIGN, SETTING, AND PARTICIPANTS

This report builds on findings from the Global Burden of Disease Study 2016, a cross-sectional study that measured diarrheal diseases and their etiologic agents. Models were used to estimate burden in data-sparse locations.

EXPOSURE

Diarrhea due to rotavirus infection.

MAIN OUTCOMES AND MEASURES

Rotavirus-associated mortality and morbidity by country and year and averted deaths attributable to the rotavirus vaccine by country.

RESULTS

Rotavirus infection was responsible for an estimated 128 500 deaths (95% uncertainty interval [UI], 104 500-155 600) among children younger than 5 years throughout the world in 2016, with 104 733 deaths occurring in sub-Saharan Africa (95% UI, 83 406-128 842). Rotavirus infection was responsible for more than 258 million episodes of diarrhea among children younger than 5 years in 2016 (95% UI, 193 million to 341 million), an incidence of 0.42 cases per child-year (95% UI, 0.30-0.53). Vaccine use is estimated to have averted more than 28 000 deaths (95% UI, 14 600-46 700) among children younger than 5 years, and expanded use of the rotavirus vaccine, particularly in sub-Saharan Africa, could have prevented approximately 20% of all deaths attributable to diarrhea among children younger than 5 years.

CONCLUSIONS AND RELEVANCE

Rotavirus-associated mortality has decreased markedly over time in part because of the introduction of the rotavirus vaccine. This study suggests that prioritizing vaccine introduction and interventions to reduce diarrhea-associated morbidity and mortality is necessary in the continued global reduction of rotavirus infection.

Design and testing of a highly conserved human rotavirus VP8* immunogenic peptide with potential for vaccine development

Rotavirus infection of young children particularly below five years of age resulting in severe diarhoea, is the cause of a large number of infant deaths all over the world, more so in developing countries like India. Vaccines developed against this infection in the last two decades have shown mixed results with some of them leading to complications. Oral vaccines have not been very effective in India. Significant diversity has been found in circulating virus strains in India. Development of a vaccine against diverse genetic variants of the different strains would go a long way in reducing the incidence of infection in developing countries. Success of such a vaccine would depend to a large extent on the antigenic peptide to be used in antibody production. The non-glycosylated protein VP4 on the surface capsid of the virus is important in rota viral immunogenicity and the major antigenic site(s) responsible for neutralization of the virus via VP4 is in the VP8* subunit of VP4. It is necessary that the peptide should be very specific and a peptide sequence which would stimulate both the T and B immunogenic cells would provide maximum protection against the virus. Advanced computational techniques and existing databases of sequences of the VP4 protein of rotavirus help in identification of such specific sequences. Using an in silico approach we have identified a highly conserved VP8* subunit of the VP4 surface protein of rotavirus which shows both T and B cell processivity and is also non-allergenic. This sub-unit could be used in in vivo models for induction of antibodies.

Rotavirus Gastroenteritis Infection Among Children Vaccinated and Unvaccinated With Rotavirus Vaccine in Southern China: A Population-Based Assessment

IMPORTANCE

Since 2000, the Lanzhou lamb rotavirus vaccine has been exclusively licensed in China for voluntary rotavirus gastroenteritis (RV-GE) prevention.

OBJECTIVE

To evaluate the association of the Lanzhou lamb rotavirus vaccination with RV-GE among children in southern China.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional, ecological study was set in Guangzhou, China. Participants were infants possibly vaccinated (aged 2 months to 3 years) and the children ineligible for vaccination (aged ≥4 years). The study was conducted from May 1, 2007, to April 30, 2016, and the data analysis was conducted in July 2016.

MAIN OUTCOMES AND MEASURES

Annual median age at onset of RV-GE and seasonal distribution of incidence. Cases of RV-GE in Guangzhou, China, diagnosed from May 1, 2007, to April 30, 2016, and reported to the National Information System for Disease Control and Prevention were examined. Poisson regression models were fitted among 32 452 children younger than 4 years and among 450 children who had been ineligible for vaccination, while controlling for secular trends, socioeconomic status, and meteorological factors. Logistic regression was used to assess the indirect effects provided by the vaccinated infants from 2009 to 2011 on unvaccinated infants aged 2 to 35 months based on a separate case-control data set.

RESULTS

During 9 seasons, 119 705 patients with gastroenteritis were reported; 33 407 were confirmed for RV-GE (21 202 [63.5%] male, 32 022 [95.8%] aged <4 years, and 31 306 [93.8%] residing in urban districts). The median age at onset for all patients with RV-GE increased from 11 months during the 2007 season to 15 months during the 2015 season, and the onset, peak, and cessation of incidence were delayed. When citywide vaccination coverage in the prior 12 months was classified into high and low groups (≥8.36% vs <8.36%), the incidence rate ratio for the high coverage group decreased by 32.4% among children younger than 4 years (incidence rate ratio, 0.676; 95% CI, 0.659-0.693; P < .001). Among the children ineligible for vaccination, the incidence rate ratio in higher coverage periods was 0.790 (95% CI, 0.351-0.915; P < .001) compared with the lower coverage. Compared with districts with 14% or less vaccination coverage, the adjusted odds ratio for RV-GE among unvaccinated children younger than 3 years was 0.85 (95% CI, 0.73-0.99; P = .03) for districts with 15% to 19% of coverage, and 0.79 (95% CI, 0.67-0.93; P = .004) for districts with more than 20% of coverage.

CONCLUSIONS AND RELEVANCE

This study provides evidence of the population health benefits of the Lanzhou lamb rotavirus vaccination in preventing RV-GE among children in China younger than 4 years, including herd effects.

Viral gastroenteritis

Enteric viruses, particularly rotaviruses and noroviruses, are a leading cause of gastroenteritis worldwide. Rotaviruses primarily affect young children, accounting for almost 40% of hospital admissions for diarrhoea and 200 000 deaths worldwide, with the majority of deaths occurring in developing countries. Two vaccines against rotavirus were licensed in 2006 and have been implemented in 95 countries as of April, 2018. Data from eight high-income and middle-income countries showed a 49-89% decline in rotavirus-associated hospital admissions and a 17-55% decline in all-cause gastroenteritis-associated hospital admissions among children younger than 5 years, within 2 years of vaccine introduction. Noroviruses affect people of all ages, and are a leading cause of foodborne disease and outbreaks of gastroenteritis worldwide. Prevention of norovirus infection relies on frequent hand hygiene, limiting contact with people who are infected with the virus, and disinfection of contaminated environmental surfaces. Norovirus vaccine candidates are in clinical trials; whether vaccines will provide durable protection against the range of genetically and antigenically diverse norovirus strains remains unknown. Treatment of viral gastroenteritis is based primarily on replacement of fluid and electrolytes.

Cynomolgus Monkeys (Macaca fascicularis) as an Experimental Infection Model for Human Group A Rotavirus

Group A rotaviruses (RVA) are one of the most common causes of severe acute gastroenteritis in infants worldwide. Rotaviruses spread from person to person, mainly by faecal–oral transmission. Almost all unvaccinated children may become infected with RVA in the first two years of life. The establishment of an experimental monkey model with RVA is important to evaluate new therapeutic approaches. In this study, we demonstrated viral shedding and viraemia in juvenile–adult Macaca fascicularis orally inoculated with Wa RVA prototype. Nine monkeys were inoculated orally: seven animals with human RVA and two control animals with saline solution. During the study, the monkeys were clinically monitored, and faeces and blood samples were tested for RVA infection. In general, the inoculated animals developed an oligosymptomatic infection pattern. The main clinical symptoms observed were diarrhoea in two monkeys for three days, associated with a reduction in plasmatic potassium content. Viral RNA was detected in seven faecal and five sera samples from inoculated animals, suggesting virus replication. Cynomolgus monkeys are susceptible hosts for human Wa RVA infection. When inoculated orally, they presented self-limited diarrhoea associated with presence of RVA infectious particles in faeces. Thus, cynomolgus monkeys may be useful as animal models to evaluate the efficacy of new antiviral approaches.

Effectiveness of Rotavirus Vaccination: A Systematic Review of the First Decade of Global Postlicensure Data, 2006-2016

Two rotavirus vaccines, Rotarix (RV1) and RotaTeq (RV5), were licensed for global use in 2006. A systematic review of 48 peer- reviewed articles with postlicensure data from 24 countries showed a median RV1 vaccine effectiveness (VE) of 84%, 75%, and 57% in countries with low, medium, and high child mortality, respectively, and RV5 VE of 90% and 45% in countries with low and high child mortality, respectively. A partial vaccine series provided considerable protection, but not to the same level as a full series. VE tended to decline in the second year of life, particularly in medium- and high-mortality settings, and tended to be greater against more severe rotavirus disease. Postlicensure data from countries across geographic regions and with different child mortality levels demonstrate that under routine use, both RV1 and RV5 are effective against rotavirus disease, supporting the World Health Organization recommendation that all countries introduce rotavirus vaccine into their national immunization program.

Epidemiological Survey of Rotaviruses Responsible for Infantile Diarrhea by the Immunomolecular Technique in Cotonou (Benin, West Africa)

Rotavirus remains the main causative agent of gastroenteritis in young children, in countries that have not yet introduced the vaccine. Benin, in order to implement the WHO recommendations, projects to introduce the rotavirus vaccine in 2018 as part of its Expanded Program on Immunization. But before the introduction of this vaccine, epidemiological data on rotavirus infections and rotavirus genotypes circulating in Benin should be available. The aim of this study is to generate epidemiological data on infantile rotavirus diarrhea in Benin. In order to determine the epidemiological characteristics and electrophoretypes of rotavirus responsible for gastroenteritis in diarrheic children aged 0 to 5 years, 186 stool samples were collected according to the WHO Rotavirus Laboratory Manual from March 2014 to February 2015 at Suru-Lere University Hospital Center. Detection of rotavirus antigen was performed by the ELISA test, followed by molecular characterization using polyacrylamide gel electrophoresis. 186 stool samples were analyzed for rotavirus, and seventy-three (39.2%) were found to be positive for rotavirus antigen by ELISA. Children aged 3 to 24 months were the most affected by rotavirus diarrhea in this study. Of the seventy-three children affected with rotavirus diarrhea, 27 (37%) had vomiting accompanied by dehydration and fever. Results based on electrophoresis showed that, among the 73 samples tested, 38 yielded typical rotavirus electrophoretic migration profiles.

Clinical characteristics and complications of rotavirus gastroenteritis in children in east London: A retrospective case-control study

Background

Rotavirus is the leading cause of acute gastroenteritis in children and is associated with neurological complications such as seizures and encephalopathy. The aim of this study was to investigate the presentation and complications of rotavirus compared to non-rotavirus gastroenteritis in UK children.

Methods

This was a retrospective, case-control, hospital-based study conducted at three sites in east London, UK. Cases were children aged 1 month to 16 years diagnosed with acute gastroenteritis between 1 June 2011 and 31 December 2013, in whom stool virology investigations confirmed presence of rotavirus by PCR. They were matched by age, gender and month of presentation to controls with rotavirus-negative gastroenteritis.

Results

Data were collected from 116 children (50 cases and 66 controls). Children with rotavirus gastroenteritis tended to present more frequently with metabolic acidosis (pH 7.30 vs 7.37, P = 0.011) and fever (74% versus 46%; P = 0.005) and were more likely to require hospitalisation compared to children with non-rotavirus gastroenteritis (93% versus 73%; P = 0.019). Neurological complications were the most common extra-intestinal manifestations, but did not differ significantly between children with rotavirus-positive gastroenteritis (RPG) and rotavirus-negative gastroenteritis (RNG) (24% versus 15%, respectively; P = 0.24). Encephalopathy occurred only in children with rotavirus infection (n = 3, 6%).

Conclusion

Rotavirus causes longer and more severe disease compared to other viral pathogens. Seizures and milder neurological signs were surprisingly common and associated with multiple pathogens, but encephalopathy occurred only in children with rotavirus gastroenteritis. Rotavirus vaccination may reduce seizures and presentation to hospital, but vaccines against other pathogens causing gastroenteritis are required.

Rotavirus infection

Rotavirus infections are a leading cause of severe, dehydrating gastroenteritis in children <5 years of age. Despite the global introduction of vaccinations for rotavirus over a decade ago, rotavirus infections still result in >200,000 deaths annually, mostly in low-income countries. Rotavirus primarily infects enterocytes and induces diarrhoea through the destruction of absorptive enterocytes (leading to malabsorption), intestinal secretion stimulated by rotavirus non-structural protein 4 and activation of the enteric nervous system. In addition, rotavirus infections can lead to antigenaemia (which is associated with more severe manifestations of acute gastroenteritis) and viraemia, and rotavirus can replicate in systemic sites, although this is limited. Reinfections with rotavirus are common throughout life, although the disease severity is reduced with repeat infections. The immune correlates of protection against rotavirus reinfection and recovery from infection are poorly understood, although rotavirus-specific immunoglobulin A has a role in both aspects. The management of rotavirus infection focuses on the prevention and treatment of dehydration, although the use of antiviral and anti-emetic drugs can be indicated in some cases.

Update on the epidemiology of rotavirus in the Middle East and North Africa

Rotavirus (RV) is the leading cause of severe acute gastroenteritis (AGE) worldwide. Consequently, we conducted a systematic literature review on articles studying RV in the 25 countries of the MENA region during the past 15years (2000-2015). The methods and reporting were set according to the 2015 preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) and based on the elements from the international prospective register of systematic reviews (PROSPERO). Our literature search identified 169 studies meeting our predefined inclusion criteria. Studies reporting on RV were conducted in 19 out of the 24 countries of the MENA region. The largest number of studies was reported in Turkey (n=32), Iran (n=31), Saudi Arabia (n=19) and Egypt (n=17). The majority of studies reporting on RV gastroenteritis rates were clinical observational studies. In 115 studies out of 169, RV was reported among in-patients whereas 35 studies reported RV among outpatients. The predominantly reported RV genotype in the region was G1[P8] followed by G2[P4] and G9[P8]. The majority of studies (n=108) were conducted among children less than 5years of age whereas the remaining studies reported on AGE among other age groups and rarely adults. In MENA countries, RV infection was reported all year round with peaks described in cold as well as hot months. This systematic review provides a current update on the epidemiology of RV-associated gastroenteritis in countries of the MENA region and draws attention to the major gaps existing in the continuous monitoring of RV.

Epidemiology of childhood intussusception in Bangladesh: Findings from an active national hospital based surveillance system, 2012-2016

INTRODUCTION

Rotavirus vaccines have significantly decreased the burden of diarrheal diseases in countries that have introduced them into their immunization programs. In some studies, there has been a small association between rotavirus vaccines and intussusception in post-marketing surveillance, highlighting the importance of tracking incidence before and after vaccine introduction. The objective of this study was to describe the epidemiology of intussusception among Bangladeshi children pre-vaccine introduction.

METHODS

We conducted active, hospital-based surveillance for intussusception at 7 tertiary care hospitals with pediatric surgical facilities during July 2012 to September 2016. Hospitalized children under 2years of age were identified according to Brighton Collaboration level 1 criteria for intussusception. The frequency and proportion of intussusception among overall surgical admissions, as well as the demographic and clinical information of the cases is described.

RESULTS

Overall 153 cases of intussusception among children <2years-old were identified at participating sites over the enrolment period, confirmed by Level 1 Brighton criteria. These cases represented 2% of all surgical admissions under 2years of age. One hundred twelve cases (73%) were male; the median age was 7months; and the median duration of hospitalization was 7days. One hundred forty-six (95%) children with intussusception required surgery, and 11 (7%) died.

CONCLUSIONS

Confirmed cases of intussusception represented nearly 2% of pediatric surgical admissions at tertiary referral centers in Bangladesh during the study period and 7% of children with intussusception died. Given the high burden of rotavirus disease in Bangladesh, vaccine introduction is warranted, however, further studies after introduction of rotavirus vaccine are necessary to determine any association between vaccine and intussusception in this setting.

Expansion of Surveillance for Vaccine-preventable Diseases: Building on the Global Polio Laboratory Network and the Global Measles and Rubella Laboratory Network Platforms

Laboratory networks were established to provide accurate and timely laboratory confirmation of infections, an essential component of disease surveillance systems. The World Health Organization (WHO) coordinates global laboratory surveillance of vaccine-preventable diseases (VPDs), including polio, measles and rubella, yellow fever, Japanese encephalitis, rotavirus, and invasive bacterial diseases. In addition to providing high-quality laboratory surveillance data to help guide disease control, elimination, and eradication programs, these global networks provide capacity-building and an infrastructure for public health laboratories. There are major challenges with sustaining and expanding the global laboratory surveillance capacity: limited resources and the need for expansion to meet programmatic goals. Here, we describe the WHO-coordinated laboratory networks supporting VPD surveillance and present a plan for the further development of these networks.

The Burden and Etiology of Diarrheal Illness in Developing Countries

Reductions in mortality from diarrheal diseases among young children have occurred in recent decades; however, approximately 500,000 children continue to die each year. Moreover, similar reductions in disease incidence have not been seen, episodes that impact the growth and development of young children. Two recent studies, MAL-ED and GEMS, have more clearly defined the burden and cause of diarrhea among young children, identifying four leading pathogens: rotavirus, CryptosporidiumShigella, and heat stable toxin-producing enterotoxigenic Escherichia coli. Global introduction of rotavirus vaccine is poised to substantially reduce the incidence of rotavirus infection. Interventions are needed to reduce the burden that remains.

Sustained low rotavirus activity and hospitalisation rates in the post-vaccination era in Belgium, 2007 to 2014

In 2006, Belgium was the first country in the European Union to recommend rotavirus vaccination in the routine infant vaccination schedule and rapidly achieved high vaccine uptake (86-89% in 2007). We used regional and national data sources up to 7 years post-vaccination to study the impact of vaccination on laboratory-confirmed rotavirus cases and rotavirus-related hospitalisations and deaths. We showed that (i) from 2007 until 2013, vaccination coverage remained at 79-88% for a complete course, (ii) in children 0-2 years, rotavirus cases decreased by 79% (95% confidence intervals (CI): 68--89%) in 2008-2014 compared to the pre-vaccination period (1999--2006) and by 50% (95% CI: 14-82%) in the age group ≥ 10 years, (iii) hospitalisations for rotavirus gastroenteritis decreased by 87% (95% CI: 84-90%) in 2008--2012 compared to the pre-vaccination period (2002--2006), (iv) median age of rotavirus cases increased from 12 months to 17 months and (v) the rotavirus seasonal peak was reduced and delayed in all post-vaccination years. The substantial decline in rotavirus gastroenteritis requiring hospitalisations and in rotavirus activity following introduction of rotavirus vaccination is sustained over time and more pronounced in the target age group, but with evidence of herd immunity.

Variation in rotavirus vaccine coverage by sub-counties in Kenya

Rotavirus gastroenteritis is an important cause of childhood morbidity and mortality in Kenya. In July 2014, Kenya introduced the rotavirus vaccine into her national immunization program. Although immunization coverage is crucial in assessing the real-world impact of this vaccine, variability in the vaccine coverage across the country is likely to occur. In view of this, we estimated the extent of coverage for the rotavirus vaccine at two socio-economically different sub-counties using the administrative data. The findings indicate disparities in vaccine coverage and access between the sub-counties and, thus, underscore the need to strengthen immunization systems to facilitate timely, accessible, and equitable vaccine delivery across the country. Both sub-counties recorded high vaccine dropout, suggestive of poor utilization of the vaccine. In this regard, increased social mobilization is needed to encourage vaccine compliance and to enhance tracking of vaccine defaulters. While efforts to improve the accuracy of the administrative coverage estimates are crucial, vaccination coverage surveys will be needed to verify the administrative coverage data and help identify specific factors relating to rotavirus vaccine coverage in the country.

Case-control vaccine effectiveness studies: Data collection, analysis and reporting results

The case-control methodology is frequently used to evaluate vaccine effectiveness post-licensure. The results of such studies provide important insight into the level of protection afforded by vaccines in a 'real world' context, and are commonly used to guide vaccine policy decisions. However, the potential for bias and confounding are important limitations to this method, and the results of a poorly conducted or incorrectly interpreted case-control study can mislead policies. In 2012, a group of experts met to review recent experience with case-control studies evaluating vaccine effectiveness; we summarize the recommendations of that group regarding best practices for data collection, analysis, and presentation of the results of case-control vaccine effectiveness studies. Vaccination status is the primary exposure of interest, but can be challenging to assess accurately and with minimal bias. Investigators should understand factors associated with vaccination as well as the availability of documented vaccination status in the study context; case-control studies may not be a valid method for evaluating vaccine effectiveness in settings where many children lack a documented immunization history. To avoid bias, it is essential to use the same methods and effort gathering vaccination data from cases and controls. Variables that may confound the association between illness and vaccination are also important to capture as completely as possible, and where relevant, adjust for in the analysis according to the analytic plan. In presenting results from case-control vaccine effectiveness studies, investigators should describe enrollment among eligible cases and controls as well as the proportion with no documented vaccine history. Emphasis should be placed on confidence intervals, rather than point estimates, of vaccine effectiveness. Case-control studies are a useful approach for evaluating vaccine effectiveness; however careful attention must be paid to the collection, analysis and presentation of the data in order to best inform evidence-based vaccine policies.

Case-control vaccine effectiveness studies: Preparation, design, and enrollment of cases and controls

Case-control studies are commonly used to evaluate effectiveness of licensed vaccines after deployment in public health programs. Such studies can provide policy-relevant data on vaccine performance under ‘real world’ conditions, contributing to the evidence base to support and sustain introduction of new vaccines. However, case-control studies do not measure the impact of vaccine introduction on disease at a population level, and are subject to bias and confounding, which may lead to inaccurate results that can misinform policy decisions. In 2012, a group of experts met to review recent experience with case-control studies evaluating the effectiveness of several vaccines; here we summarize the recommendations of that group regarding best practices for planning, design and enrollment of cases and controls. Rigorous planning and preparation should focus on understanding the study context including healthcare-seeking and vaccination practices. Case-control vaccine effectiveness studies are best carried out soon after vaccine introduction because high coverage creates strong potential for confounding. Endpoints specific to the vaccine target are preferable to non-specific clinical syndromes since the proportion of non-specific outcomes preventable through vaccination may vary over time and place, leading to potentially confusing results. Controls should be representative of the source population from which cases arise, and are generally recruited from the community or health facilities where cases are enrolled. Matching of controls to cases for potential confounding factors is commonly used, although should be reserved for a limited number of key variables believed to be linked to both vaccination and disease. Case-control vaccine effectiveness studies can provide information useful to guide policy decisions and vaccine development, however rigorous preparation and design is essential.

The rotavirus vaccine development pipeline

Rotavirus disease is a leading global cause of mortality and morbidity in children under 5 years of age. The effectiveness of the two globally used oral rotavirus vaccines quickly became apparent when introduced into both developed and developing countries, with significant reductions in rotavirus-associated mortality and hospitalizations. However, the effectiveness and impact of the vaccines is reduced in developing country settings, where the burden and mortality is highest.

New rotavirus vaccines, including live oral rotavirus candidates and non-replicating approaches continue to be developed, with the major aim to improve the global supply of rotavirus vaccines and for local implementation, and to improve vaccine effectiveness in developing settings. This review provides an overview of the new rotavirus vaccines in development by developing country manufacturers and provides a rationale why newer candidates continue to be explored. It describes the new live oral rotavirus vaccine candidates as well as the non-replicating rotavirus vaccines that are furthest along in development.

Efficacy of a Low-Cost, Heat-Stable Oral Rotavirus Vaccine in Niger

BACKGROUND

Each year, rotavirus gastroenteritis is responsible for about 37% of deaths from diarrhea among children younger than 5 years of age worldwide, with a disproportionate effect in sub-Saharan Africa.

METHODS

We conducted a randomized, placebo-controlled trial in Niger to evaluate the efficacy of a live, oral bovine rotavirus pentavalent vaccine (BRV-PV, Serum Institute of India) to prevent severe rotavirus gastroenteritis. Healthy infants received three doses of the vaccine or placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis were assessed through active and passive surveillance and were graded on the basis of the score on the Vesikari scale (which ranges from 0 to 20, with higher scores indicating more severe disease). The primary end point was the efficacy of three doses of vaccine as compared with placebo against a first episode of laboratory-confirmed severe rotavirus gastroenteritis (Vesikari score, ≥11) beginning 28 days after dose 3.

RESULTS

Among the 3508 infants who were included in the per-protocol efficacy analysis, there were 31 cases of severe rotavirus gastroenteritis in the vaccine group and 87 cases in the placebo group (2.14 and 6.44 cases per 100 person-years, respectively), for a vaccine efficacy of 66.7% (95% confidence interval [CI], 49.9 to 77.9). Similar efficacy was seen in the intention-to-treat analyses, which showed a vaccine efficacy of 69.1% (95% CI, 55.0 to 78.7). There was no significant between-group difference in the risk of adverse events, which were reported in 68.7% of the infants in the vaccine group and in 67.2% of those in the placebo group, or in the risk of serious adverse events (in 8.3% in the vaccine group and in 9.1% in the placebo group); there were 27 deaths in the vaccine group and 22 in the placebo group. None of the infants had confirmed intussusception.

CONCLUSIONS

Three doses of BRV-PV, an oral rotavirus vaccine, had an efficacy of 66.7% against severe rotavirus gastroenteritis among infants in Niger. (Funded by Médecins sans Frontières Operational Center and the Kavli Foundation; ClinicalTrials.gov number, NCT02145000 .).