Health Impact of Rotavirus Vaccination in Developing Countries: Progress and Way Forward

Long-term impact of rotavirus vaccination on all-cause and rotavirus-specific gastroenteritis and strain distribution in Central Kenya: An 11-year interrupted time-series analysis

BACKGROUND

Kenya introduced a monovalent rotavirus vaccine administered orally at 6 and 10 weeks of age into her National Immunization Program in July 2014. The study evaluated the long-term impact of the vaccine on hospitalization for all-cause and rotavirus-specific acute gastroenteritis (AGE) and strain epidemiology in Kenya.

METHODS

Data on all-cause and rotavirus-specific AGE and strain distribution were derived from an eleven-year hospital-based surveillance of AGE among children aged <5 years at Kiambu County Teaching and Referral Hospital (KCTRH) in Central Kenya between 2009 and 2020. Fecal samples were screened for group A rotavirus using ELISA and genotyped using multiplex semi-nested RT-PCR. Trends in all-cause and rotavirus-related AGE and strain distribution were compared between the pre-vaccine (July 2009-June 2014), early post-vaccine (July 2014-June 2016) and late post-vaccine (February 2019-October 2020) periods.

RESULTS

Rotavirus-specific AGE was detected at 27.5% (429/1546, 95% CI: 25.5-30.1%) in the pre-vaccine period; 13.8% (91/658, 95% CI: 11.3-16.6%) in the early post-vaccine period (July 2014-June 2016); and 12.0% (229/1916, 95% CI: 10.6-13.5%) in the late post-vaccine period (February 2019-October 2020). This amounted to a decline of 49.8% (95% CI: 34.6%-63.7%) in rotavirus-specific AGE in the early post-vaccine period and 53.4% (95% CI: 41.5-70.3%) in the late post-vaccine period when compared to the pre-vaccine period. All-cause AGE hospitalizations declined by 40.2% (95% CI: 30.8%-50.2%) and 75.3% (95% CI: 65.9-83.1%) in the early post-vaccine and late post-vaccine periods, respectively, when compared to the pre-vaccine period. G3P [8] was the predominant strain in the late post-vaccine period, replacing G1P[8] which had predominated in the pre-vaccine and early post-vaccine periods. Additionally, we detected considerable proportions of uncommon strains G3P[6] (4.8%) and G12P[6] (3.5%) in the post-vaccine era.

CONCLUSION

Rotavirus vaccination has resulted in a significant decline in all-cause and rotavirus-specific AGE, and thus, provides strong evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunization. However, the shift in strain dominance and age distribution of rotavirus AGE in the post-vaccine era underscores the need for continued surveillance to assess any possible vaccine-induced selective pressure that could diminish the vaccine effectiveness over time.

Differences in Rotavirus Shedding and Duration by Infant Oral Rotavirus Vaccination Status in Dhaka, Bangladesh, 2011-2014

To evaluate how breakthrough rotavirus disease contributes to transmission, we examined the impact of rotavirus vaccination on fecal shedding and duration of illness. We used multivariable linear regression to analyze rotavirus quantity by RT-qPCR and duration among 184 episodes of rotavirus diarrhea positive by ELISA in the PROVIDE study. Vaccinated children had less fecal viral shedding compared to unvaccinated children (mean difference = -0.59 log copies per gram of stool; 95% confidence interval [CI], -.99 to -.19). Duration of illness was on average 0.47 days (95% CI, -.23 to 1.17 days) shorter among vaccinated children. Rotarix vaccination reduces shedding burden among breakthrough cases of rotavirus gastroenteritis. Clinical Trials Registration . NCT01375647.

Prediction of effectiveness of universal rotavirus vaccination in Southwestern Vietnam based on a dynamic mathematical model

Vaccinating young children against rotavirus (RV) is a promising preventive strategy against rotavirus gastroenteritis (RVGE). We evaluated the relative risk reduction of RVGE induced by universal vaccination in Vietnam through dynamic model analysis. We developed an age-stratified dynamic Vaccinated-Susceptible-Infectious-Recovered-Susceptible model to analyze RV transmission and assess vaccine effectiveness (VE). We assumed 3 different vaccine efficacies: 55%, 70%, and 85%. For model calibration, we used a database of patients under 5 years of age admitted to Ho Chi Minh No.1 Hospital with RVGE between January 2013 and December 2018. Assuming a vaccination rate of 95%, the number of RVGE hospitalizations after 5 years from universal RV vaccination decreased from 92,502 cases to 45,626 with 85% efficacy, to 54,576 cases with 70% efficacy, and to 63,209 cases with 55% efficacy. Additionally, RVGE hospitalizations after 10 years decreased from 177,950 to 89,517 with 85% efficacy and to 121,832 cases with 55% efficacy. The relative risk reductions of RVGE after 10 years were 49.7% with 85% efficacy, 40.6% with 70% efficacy, and 31.5% with 55% efficacy. The VE was 1.10 times (95% CI, 1.01-1.22) higher in the 4-months to 1-year-old age group than in the other age groups (P = 0.038), when applying 85% efficacy with 95% coverage. In conclusion, despite its relatively lower efficacy compared to high-income countries, RV vaccination remains an effective intervention in Southwestern Vietnam. In particular, implementing universal RV vaccination with higher coverage would result in a decrease in RVGE hospitalizations among Vietnamese children under 5 years of age.

Mining for crypto protection: a search for Cryptosporidium antibodies reveals antigens associated with immunity

Infectious diarrhea is a major cause of morbidity and mortality, particularly for children in low- and middle-income countries. Cryptosporidium is a diarrheal pathogen for which there is no vaccine and current therapies are only partially effective. In this issue of the JCI, Gilchrist, Campo, and colleagues surveyed a large cohort of Bangladeshi children to profile antibody responses against an array of Cryptosporidium proteins. They discovered 233 proteins to which children developed antibodies, identified seven as being associated with protection from reinfection, and provided insights regarding the longevity of Cryptosporidium antibodies and the development of antibody breadth. In this commentary, we discuss the burden of disease caused by Cryptosporidium and how these studies highlight the strategies to better manage this parasite.

Potential impact of rotavirus vaccination on reduction of childhood diarrheal disease in India: An analysis of National Family Health Survey-5

Rotavirus is one of the leading causes of diarrhea in infants and young children worldwide. In this study, we investigated the impact of rotavirus vaccination on the prevalence of diarrheal disease among children under five years of age in India. Research on the impact of the rotavirus vaccine on reducing diarrheal disease is therefore important in contributing to the growing body of evidence on the effectiveness of this intervention in improving child health outcomes. We adopted multivariate logistic regression and propensity score matching analysis to examine the association between diarrhea and the rotavirus vaccine. The bivariate analysis finding shows that the prevalence of diarrhea was remarkably higher (9.1%) among children who had not received rotavirus and the prevalence was 7.5%, 7.5%, and 7.2% among children who received one dose, two doses, and three rotavirus doses (all) respectively. The result of multivariate logistic regression shows that children who received all three doses of the rotavirus vaccine were 16% less likely to experience diarrhea compared to those who did not receive any rotavirus vaccine. Our analysis also found that the prevalence of diarrhea decreased significantly in the years following the introduction of the vaccine. The results of this study suggest that the rotavirus vaccine has a significant impact on reducing childhood diarrheal disease in India. These results have the potential to inform policy decisions and enable healthcare professionals to concert their efforts in reducing the diarrheal disease burden and its timely prevention in children. The study will also contribute to the existing literature on the impact of rotavirus vaccination in reducing the prevalence of diarrhea among children in India.

Deployment of Rotavirus Vaccine in Western Kenya Coincides with a Reduction in All-Cause Child Mortality: A Retrospective Cohort Study

Rotavirus is an important cause of fatal pediatric diarrhea worldwide. Many national immunization programs began adding rotavirus vaccine following a 2009 World Health Organization recommendation. Kenya added rotavirus vaccine to their immunization program at the end of 2014. From a cohort of 38,463 children in the Kisumu health and demographic surveillance site in western Kenya, we assessed how the implementation of the rotavirus vaccine affected mortality in children under 3 years of age. Following its introduction in late 2014, the span of rotavirus vaccine coverage for children increased to 75% by 2017. Receiving the rotavirus vaccine was associated with a 44% reduction in all-cause child mortality (95% confidence interval = 28-68%, p < 0.0001), but not diarrhea-specific mortality (p = 0.401). All-cause child mortality declined 2% per month following the implementation of the rotavirus vaccine (p = 0.002) among both vaccinated and unvaccinated children, but diarrhea-specific mortality was not associated with the implementation of the rotavirus vaccine independent of individual vaccine status (p = 0.125). The incidence of acute diarrhea decreased over the study period, and the introduction of the rotavirus vaccine was not associated with population-wide trends (p = 0.452). The receipt of the rotavirus vaccine was associated with a 34% reduction in the incidence of diarrhea (95% confidence interval = 24-43% reduction). These results suggest that rotavirus vaccine may have had an impact on all-cause child mortality. The analyses of diarrhea-specific mortality were limited by relatively few deaths (n = 57), as others have found a strong reduction in diarrhea-specific mortality. Selection bias may have played a part in these results-children receiving rotavirus vaccine were more likely to be fully immunized than children not receiving the rotavirus vaccine.

Advances in the development of antivirals for rotavirus infection

Rotavirus (RV) causes 200,000 deaths per year and imposes a serious burden to public health and livestock farming worldwide. Currently, rehydration (oral and intravenous) remains the main strategy for the treatment of rotavirus gastroenteritis (RVGE), and no specific drugs are available. This review discusses the viral replication cycle in detail and outlines possible therapeutic approaches including immunotherapy, probiotic-assisted therapy, anti-enteric secretory drugs, Chinese medicine, and natural compounds. We present the latest advances in the field of rotavirus antivirals and highlights the potential use of Chinese medicine and natural compounds as therapeutic agents. This review provides an important reference for rotavirus prevention and treatment.

Public health impact and cost-effectiveness of rotavirus vaccination in China: Comparison between private market provision and national immunization programs

In China, progress to include the RV vaccine in the national immunization program (NIP) is slow. The only two vaccines, the Lanzhou lamb rotavirus vaccine (LLR) and Rotateq, are provided through the private market. This study aims to assess the health impact and cost-effectiveness of using three vaccines in the NIP, Rotateq, Rotarix, and LLR, compared to the status quo. A decision-tree Markov model was adopted to follow the 2019 birth cohort, and a societal perspective was used. Input parameters were based on the latest local data when possible. Outcomes included cases and deaths averted, quality-adjusted life years (QALYs) gained, and incremental cost-effectiveness ratios (ICER). Sensitivity analyses and scenario analyses to consider herd immunity and vaccine price reduction were performed. Including Rotateq in the NIP was projected to prevent 348 million RVGE cases (62.6% reduction) and 4251 deaths (72.6% reduction) compared to the status quo. Rotarix through the NIP would prevent 48.7% of cases and 63.2% of deaths, and LLR would avert 20.3% of cases and 22.4% of deaths. The ICERs per QALY gained were US$ 8833 for Rotateq through the NIP, US$ 9503 for Rotarix, and US$ 26,759 for LLR. In uncertainty analyses, the reduction of vaccine prices and the incorporation of herd immunity further improved the cost-effectiveness of the NIPs, especially Rotateq or Rotarix. In conclusion, introducing the RV vaccine in China's NIP is expected to be cost-effective compared to the GDP per capita. Reducing vaccine prices and adopting vaccines with better efficacy would be the future focus.

Current and next-generation formulation strategies for inactivated polio vaccines to lower costs, increase coverage, and facilitate polio eradication

Implementation of inactivated polio vaccines (IPV) containing Sabin strains (sIPV) will further enable global polio eradication efforts by improving vaccine safety during use and containment during manufacturing. Moreover, sIPV-containing vaccines will lower costs and expand production capacity to facilitate more widespread use in low- and middle-income countries (LMICs). This review focuses on the role of vaccine formulation in these efforts including traditional Salk IPV vaccines and new sIPV-containing dosage forms. The physicochemical properties and stability profiles of poliovirus antigens are described. Formulation approaches to lower costs include developing multidose and combination vaccine formats as well as improving storage stability. Formulation strategies for dose-sparing and enhanced mucosal immunity include employing adjuvants (e.g. aluminum-salt and newer adjuvants) and/or novel delivery systems (e.g. ID administration with microneedle patches). The potential for applying these low-cost formulation development strategies to other vaccines to further improve vaccine access and coverage in LMICs is also discussed.

Viral pathogens of acute gastroenteritis in Egyptian children: role of the parechovirus

BACKGROUND AND AIM

Human parechovirus (HPeV) has emerged as a pathogen associated with acute gastroenteritis (AGE).

AIM

To detect the presence of HPeV in the stool samples from Egyptian children with AGE seeking care and the possibility of its co-infection with other enteric viruses.

METHODOLOGY

One hundred stool samples were collected from children attending Mansoura University Children's Hospital with AGE. HPeV and astrovirus were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). At the same time, detection of rotavirus antigen and norovirus was achieved by enzyme-linked immunosorbent assay and rapid immunochromatographic method, respectively.

RESULTS

The most frequently detected virus was rotavirus (39%), followed by norovirus (27%), HPeV (19%), and astrovirus (12%). Interestingly, the single infection with HPeV was 5%. Among the 19 HPeV positive samples, the co-infection of HPeV with other enteric viruses was detected in 9(43.9%) for rotavirus, 7(36.8%) for norovirus, 2(10.5%) for astrovirus, in 3(15.8%) for rotavirus and norovirus and 1(5.3%) for norovirus and astrovirus. Regarding the clinical presentation, there was no significant difference between children infected with HPeV alone and those infected with viruses other than HPeV alone; fever (p = 0.3), vomiting (p = 0.12), abdominal pain (p = 0.12), and grades of severity (P = 0.82). HPeV alone infected children were of mild severity (60%), and their main presenting symptom was fever (60%).

CONCLUSIONS

Detection of HPeV as a single viral pathogen in the stool of some children with AGE showed that this virus could be a causative agent of AGE in Egyptian children. Therefore, HPeV could be included as one of the viruses screened for AGE diagnosis in children in Egypt.

T-Cell Responses after Rotavirus Infection or Vaccination in Children: A Systematic Review

Cellular immunity against rotavirus in children is incompletely understood. This review describes the current understanding of T-cell immunity to rotavirus in children. A systematic literature search was conducted in Embase, MEDLINE, Web of Science, and Global Health databases using a combination of “t-cell”, “rotavirus” and “child” keywords to extract data from relevant articles published from January 1973 to March 2020. Only seventeen articles were identified. Rotavirus-specific T-cell immunity in children develops and broadens reactivity with increasing age. Whilst occurring in close association with antibody responses, T-cell responses are more transient but can occur in absence of detectable antibody responses. Rotavirus-induced T-cell immunity is largely of the gut homing phenotype and predominantly involves Th1 and cytotoxic subsets that may be influenced by IL-10 Tregs. However, rotavirus-specific T-cell responses in children are generally of low frequencies in peripheral blood and are limited in comparison to other infecting pathogens and in adults. The available research reviewed here characterizes the T-cell immune response in children. There is a need for further research investigating the protective associations of rotavirus-specific T-cell responses against infection or vaccination and the standardization of rotavirus-specific T-cells assays in children.

Effect of rotavirus genetic diversity on vaccine impact

Group A rotaviruses (RVAs) are the leading cause of gastroenteritis, causing 0.2 million deaths and several million hospitalisations globally each year. Four rotavirus vaccines (Rotarix^TM , RotaTeq^TM , Rotavac^® and ROTASIIL^® ) have been pre-qualified by the World Health Organization (WHO), but the two newly pre-qualified vaccines (Rotavac^® and ROTASIIL^® ) are currently only in use in Palestine and India, respectively. In 2009, WHO strongly proposed that rotavirus vaccines be included in the routine vaccination schedule of all countries around the world. By the end of 2019, a total of 108 countries had administered rotavirus vaccines, and 10 countries have currently been approved by Gavi for the introduction of rotavirus vaccine in the near future. With 39% of global coverage, rotavirus vaccines have had a substantial effect on diarrhoeal morbidity and mortality in different geographical areas, although efficacy appears to be higher in high income settings. Due to the segmented RNA genome, the pattern of RVA genotypes in the human population is evolving through interspecies transmission and/or reassortment events for which the vaccine might be less effective in the future. However, despite the relative increase in some particular genotypes after rotavirus vaccine use, the overall efficacy of rotavirus mass vaccination worldwide has not been affected. Some of the challenges to improve the effect of current rotavirus vaccines can be solved in the future by new rotavirus vaccines and by vaccines currently in progress.

Formulation development of a live attenuated human rotavirus (RV3-BB) vaccine candidate for use in low- and middle-income countries

Formulation development was performed with the live, attenuated, human neonatal rotavirus vaccine candidate (RV3-BB) with three main objectives to facilitate use in low- and middle- income countries including (1) a liquid, 2-8°C stable vaccine, (2) no necessity for pre-neutralization of gastric acid prior to oral administration of a small-volume dose, and (3) a low-cost vaccine dosage form. Implementation of a high-throughput RT-qPCR viral infectivity assay for RV3-BB, which correlated well with traditional FFA assays in terms of monitoring RV3-BB stability profiles, enabled more rapid and comprehensive formulation development studies. A wide variety of different classes and types of pharmaceutical excipients were screened for their ability to stabilize RV3-BB during exposure to elevated temperatures, freeze-thaw and agitation stresses. Sucrose (50-60% w/v), PEG-3350, and a solution pH of 7.8 were selected as promising stabilizers. Using a combination of an in vitro gastric digestion model (to mimic oral delivery conditions) and accelerated storage stability studies, several buffering agents (e.g., succinate, adipate and acetate at ~200 to 400 mM) were shown to protect RV3-BB under acidic conditions, and at the same time, minimize virus destabilization during storage. Several optimized RV3-BB candidate formulations were identified based on negligible viral infectivity losses during storage at 2-8°C and -20°C for up to 12 months, as well as by relative stability comparisons at 15°C and 25°C (up to 12 and 3 months, respectively). These RV3-BB stability results are discussed in the context of stability profiles of other rotavirus serotypes as well as future RV3-BB formulation development activities.

Genetic characterization and phylogenetic variations of human adenovirus-F strains circulating in eastern India during 2017-2020

Human adenovirus-F (HAdV-F) (genotype 40/41) is the second-most leading cause of pediatric gastroenteritis after rotavirus, worldwide, accounting for 2.8%-11.8% of infantile diarrheal cases. Earlier studies across eastern India revealed a shift in the predominance of genotypes from HAdV41 in 2007-09 to HAdV40 in 2013-14. Thus, the surveillance for HAdV-F genotypes in this geographical setting was undertaken over 2017-2020 to analyze the viral evolutionary dynamics. A total of 3882 stool samples collected from children (≤5 years) were screened for HAdV-F positivity by conventional PCR. The hypervariable regions of the hexon and the partial shaft region of long fiber genes were amplified, sequenced, and phylogenetically analyzed with respect to the prototype strains. A marginal decrease in enteric HAdV prevalence was observed (9.04%, n = 351/3882) compared to the previous report (11.8%) in this endemic setting. Children <2 years were found most vulnerable to enteric HAdV infection. Reduction in adenovirus-rotavirus co-infection was evident compared to the sole adenovirus infection. HAdV-F genotypes 40 and 41 were found to co-circulate, but HAdV41 was predominant. HAdV40 strains were genetically conserved, whereas HAdV41 strains accumulated new mutations. On the basis of a different set of mutations in their genome, HAdV41 strains segregated into 2 genome type clusters (GTCs). Circulating HAdV41 strains clustered with GTC1 of the fiber gene, for the first time during this study period. This study will provide much-needed baseline data on the emergence and circulation of HAdV40/41 strains for future vaccine development.

Wa-1 Equine-Like G3P[8] Rotavirus from a Child with Diarrhea in Colombia

Rotavirus A (RVA) has been considered the main cause of diarrheal disease in children under five years in emergency services in both developed and developing countries. RVA belongs to the Reoviridae family, which comprises 11 segments of double-stranded RNA (dsRNA) as a genomic constellation that encodes for six structural and five to six nonstructural proteins. RVA has been classified in a binary system with Gx[Px] based on the spike protein (VP4) and the major outer capsid glycoprotein (VP7), respectively. The emerging equine-like G3P[8] DS-1-like strains reported worldwide in humans have arisen an important concern. Here, we carry out the complete genome characterization of a previously reported G3P[8] strain in order to recognize the genetic diversity of RVA circulating among infants in Colombia. A near-full genome phylogenetic analysis was done, confirming the presence of the novel equine-like G3P[8] with a Wa-like backbone for the first time in Colombia. This study demonstrated the importance of surveillance of emerging viruses in the Colombian population; furthermore, additional studies must focus on the understanding of the spread and transmission dynamic of this important RVA strain in different areas of the country.

Rotavirus Genotype Trends and Gastrointestinal Pathogen Detection in the United States, 2014-16: Results from the New Vaccine Surveillance Network

BACKGROUND

Following the implementation of rotavirus vaccination in 2006, severe acute gastroenteritis (AGE) due to group A rotavirus (RVA) has substantially declined in USA (US) children. We report the RVA genotype prevalence as well as co-infection data from seven US New Vaccine Surveillance Network (NVSN) sites during three consecutive RVA seasons, 2014-2016.

METHODS

A total of 1041 stool samples that tested positive for RVA by Rotaclone enzyme immunoassay (EIA) were submitted to the Centers for Disease Control and Prevention (CDC) for RVA genotyping and multipathogen testing.

RESULTS

A total of 795 (76%) contained detectable RVA at CDC. Rotavirus disease was highest in children < 3 years of age. Four G types (G1, G2, G9, and G12) accounted for 94.6% of strains while two P types (P[4] and P[8]) accounted 94.7% of the strains. Overall, G12P[8] was the most common genotype detected in all three seasons. Stepwise conditional logistic analysis found year and study site were significant predictors of genotype. Twenty four percent (24%) of RVA-positive specimens contained other AGE pathogens.

CONCLUSIONS

G12P[8] predominated over three seasons, but strain predominance varied by year and study site. Ongoing surveillance provides continuous tracking and monitoring of US genotypes during the post vaccine era.

Duration and Density of Fecal Rotavirus Shedding in Vaccinated Malawian Children With Rotavirus Gastroenteritis

Quantifying rotavirus shedding among vaccinated individuals will aid understanding of vaccine indirect effects. Serial stool samples were collected from 196 children who presented with rotavirus gastroenteritis to health facilities in Blantyre, Malawi, and were tested for rotavirus using a VP6 semi-quantitative, real-time polymerase chain reaction. The median duration of fecal shedding was 28 days (95% CI, 19–28). The median copy numbers for peak shedding were 1.99 × 10⁷ (interquartile range, 3.39 × 10⁶ to 6.37 × 10⁷). The fecal viral load was positively associated with disease severity and negatively associated with serum anti-rotavirus immunoglobin A. High and persistent rotavirus shedding among vaccinated children with breakthrough disease may contribute to ongoing transmission in this setting.

Acute Gastroenteritis in Children Below 5 Years of Age at Tirupati, Andhra Pradesh, India Post Introduction of Rotavirus Vaccine into National Immunization Programme

OBJECTIVE

To identify the burden of rotavirus acute gastroenteritis (AGE) and the genotypes presenting in the authors' area in the period after introduction of rotavirus vaccine in Universal Immunization Programme (UIP).

METHODS

Children aged less than 5 y and presenting to hospital for the treatment of AGE were enrolled into the study from January 2016 to June 2019. Clinical details including age, gender, extent of illness, number of stools, concomitant vomiting and fever, grade of dehydration, and associated illness were recorded. Stool samples were tested for rotavirus using a commercially available ELISA Kit. Genotyping was performed for the rotavirus antigen-positive samples.

RESULTS

Rotavirus positive AGE was seen in 14.2% of the children. High burden of rotavirus gastroenteritis was seen in the age group of 6-23 mo and more cases were observed from December to February months. In our region the prevalent rotavirus genotypes in positive samples are G3 and G1 in G-typing, P[8] and P[4] in P-typing, respectively. G3P[8] and G1P[8] are the most prevalent genotypes identified in our area with a frequency of 35.1% and 25.9%, respectively. Almost all the cases (97.7%) got discharged and only one patient has died.

CONCLUSION

The findings conclude a declining trend in the rotavirus positive AGE cases in the authors' area after introduction of Rotavac vaccine in the UIP.

Diarrheal Deaths After the Introduction of Rotavirus Vaccination in 4 Countries

BACKGROUND

We aim in our analysis to estimate the reduction of diarrhea-related mortality rates after introduction of a rotavirus vaccine in subregions of 4 Latin American countries.

METHODS

We selected diarrhea-related deaths from individual-level data from death certificates in Brazil, Colombia, Ecuador, and Mexico. Counts were aggregated by region, year and month, and age group for each country. We ran an interrupted time-series analysis using Poisson regression to obtain seasonal and trend-adjusted estimates of impact. Results are reported as percentages (1 - mortality rate ratio).

RESULTS

We found a reduction in diarrhea-related mortality in children <5 years old of 18% (95% confidence interval [CI], 15 to 20) for Mexico, 39% (95% CI, 35 to 44) for Colombia, 19 (95% CI, 17 to 22) for Brazil, and -26% (95% CI, -40 to -14) for Ecuador. Using wavelet analyses, we found a reduction of 6- and 12-month seasonality in Brazil, Colombia, and Mexico. We also found that the increased reduction of diarrhea-related deaths was larger with greater prevaccine burden of diarrhea in infants.

CONCLUSIONS

Our findings and available evidence support the recommendation from the World Health Organization for the monovalent and/or pentavalent rotavirus vaccine in countries worldwide. We found an increased benefit in those settings with a higher burden of infant diarrhea-related deaths.

A pilot study on use of live attenuated rotavirus vaccine (Rotarix™) as an infection challenge model

BACKGROUND

Rotavirus remains the commonest cause of dehydrating diarrhoea, particularly in developing countries. Human infection challenge studies in children in these countries offers an opportunity to rapidly evaluate new vaccine candidates that may have improved efficacy. We evaluated use of Rotarix™ as a live-attenuated challenge agent.

METHODS

We undertook an open label, exploratory study in infants receiving two standard doses of Rotarix™ at 6 and 10 weeks of age in a cohort of 22 Zambian infants. The first vaccine dose was considered as primary vaccination, and the second at day 28 as a live-attenuated virus challenge. Saliva, stool and serum samples were collected on days 0, 3, 5, 7, 14, and 28 following each dose. The primary outcome was stool shedding of rotavirus, determined by NSP2 qPCR. We calculated mean shedding index as average of natural logarithm of viral copies per gram of stool.

FINDINGS

After the first dose, viral shedding was high at day 3, peaked by day 5. After the second dose, viral shedding at day 3 was low and reduced gradually in most infants until day 14. Mean shedding index was significantly lower post dose 2 across all infants and timepoints (5.0 virus copies/g of stool [95%CI: 0.3-9.7] vs 10.4 virus copies/g of stool [95%CI: 6.2-14.6]; p-value < 0.0001; rho = 0.20, SD = 4.97. Seroconversion at day 28 was associated with a mean reduction of -1.03 (95%CI = -8.07, 6.01) in viral shedding after challenge dose but this was not statistically significant (p = 0.774). A borderline positive correlation between fold-change in IgA titre at day 28 from day 0 in saliva and serum was observed; Spearman's correlation coefficient, r = 0.69; p = 0.086.

INTERPRETATION

Shedding after the 'challenge' dose was reduced compared with the first dose, consistent with the induction of mucosal immunity by the first dose. This supports the use of Rotarix vaccine as a live-attenuated infection challenge.

FUNDING

Medical Research Council (UK) through the HIC-Vac Network.

An overview of rotavirus vaccination programs in developing countries

INTRODUCTION

Rotavirus is the leading cause of acute diarrhea among children <5 years worldwide. As all children are equally susceptible to infection and disease development, rotavirus vaccination programs are the best upstream approach to preventing rotavirus disease, and the subsequent risk of hospitalization or death.

AREAS COVERED

We provide an overview of global rotavirus vaccine policy, summarize the burden of rotavirus disease in developing countries, review data on the effectiveness, impact, safety, and the cost-effectiveness of rotavirus vaccination programs, and identify areas for further research and improvement.

EXPERT OPINION

Rotavirus vaccines continue to be an effective, safe, and cost-effective solution to preventing rotavirus disease. As two new rotavirus vaccines enter the market (Rotasiil and Rotavac) and Asian countries continue to introduce rotavirus vaccines into their national immunization programs, documenting vaccine safety, effectiveness, and impact in these settings will be paramount.

Clinical and Environmental Surveillance of Rotavirus Common Genotypes Showed High Prevalence of Common P Genotypes in Egypt

The objective of this study was to compare the prevalence of human rotavirus group A common G and P genotypes in human Egyptian stool specimens and raw sewage samples to determine the most common genotypes for future vaccine development. From 1026 stool specimens of children with acute diarrhea and using nested RT-PCR, 250 samples (24.37%) were positive for human rotavirus group A. Using multiplex RT-PCR, rotavirus common P and G genotypes were detected as 89.20% and 46.40% of the positive clinical specimens respectively. This low percentage of common G genotypes frequency may affect the efficiency of the available live attenuated oral rotavirus vaccines [Rotarix® (human rotavirus G1P[8]) and RotaTeq® (reassortant bovine-human rotavirus G1-4P[5] and G6P[8])], however the percentage of clinical specimens which were negative for common G genotypes but positive for P[8] genotype was 12.00%. From 24 positive raw sewage samples for rotavirus group A VP6 collected from Zenin and El-Gabal El-Asfar wastewater treatment plants (WWTPs), 21 samples (87.50%) were typeable for common P genotypes while 13 samples (54.17%) were typeable for common G genotypes. Phylogenetic analysis of a VP8 partial gene of 45 P-typeable clinical isolates and 20 P-typeable raw sewage samples showed high similarity to reference strains and the majority of mutations were silent and showed lower to non-significant similarity with the two vaccine strains. This finding is useful for determining the most common antigens required for future vaccine development.

Effectiveness of Monovalent Rotavirus Vaccine Against Hospitalization With Acute Rotavirus Gastroenteritis in Kenyan Children

BACKGROUND

Rotavirus remains a leading cause of pediatric diarrheal illness and death worldwide. Data on rotavirus vaccine effectiveness in sub-Saharan Africa are limited. Kenya introduced monovalent rotavirus vaccine (RV1) in July 2014. We assessed RV1 effectiveness against rotavirus-associated hospitalization in Kenyan children.

METHODS

Between July 2014 and December 2017, we conducted surveillance for acute gastroenteritis (AGE) in 3 Kenyan hospitals. From children age-eligible for ≥1 RV1 dose, with stool tested for rotavirus and confirmed vaccination history we compared RV1 coverage among rotavirus positive (cases) vs rotavirus negative (controls) using multivariable logistic regression and calculated effectiveness based on adjusted odds ratio.

RESULTS

Among 677 eligible children, 110 (16%) were rotavirus positive. Vaccination data were available for 91 (83%) cases; 51 (56%) had 2 RV1 doses and 33 (36%) 0 doses. Among 567 controls, 418 (74%) had vaccination data; 308 (74%) had 2 doses and 69 (16%) 0 doses. Overall 2-dose effectiveness was 64% (95% confidence interval [CI], 35%-80%); effectiveness was 67% (95% CI, 30%-84%) for children aged <12 months and 72% (95% CI, 10%-91%) for children aged ≥12 months. Significant effectiveness was seen in children with normal weight for age, length/height for age and weight for length/height; however, no protection was found among underweight, stunted, or wasted children.

CONCLUSIONS

RV1 in the Kenyan immunization program provides significant protection against rotavirus-associated hospitalization which persisted beyond infancy. Malnutrition appears to diminish vaccine effectiveness. Efforts to improve rotavirus uptake and nutritional status are important to maximize vaccine benefit.

Evidence of rotavirus vaccine impact in sub-Saharan Africa: Systematic review and meta-analysis

BACKGROUND

Over 34 countries in Africa have introduced rotavirus vaccine to their national immunization programs: monovalent (Rotarix®, RV1) and pentavalent (RotaTeq®, RV5) after South Africa introduced it in 2009. Since then several studies assessing the impact of the vaccine have been conducted. The principal aim of this study was to evaluate the impact of rotavirus vaccine in sub-Saharan Africa.

METHODS

A Literature search was performed using Mendeley, PubMed, ScienceDirect, grey literature and Web of Science databases of published studies from January 1, 2017, as years of recent publications on rotavirus vaccine impact in sub-Saharan Africa. A meta-analysis was conducted for rotavirus infection in children under 5 years using proportions of pre and post-vaccine introduction in these populations. Random-effect estimates were considered since the samples were from universal populations.

RESULTS

Out of the 935 articles identified, 17 studies met the inclusion for systematic review and meta-analysis. The pooled proportion for pre-vaccination period was 42%, 95% (CI: 38-46%), and reduced to 21%, 95% (CI: 17-25%) during post-vaccination period. Rotavirus diarrhea significantly reduced in children < 12 months as compared to children 12-24 months old. Seasonal peaks of rotavirus diarrhea were between June-September. However, data is limited to one year of post-vaccine introduction, and bias may present due to early vaccine impact.

CONCLUSION

We observed that the introduction of the rotavirus vaccine was partly responsible for the significant reduction in the burden of rotavirus-associated diarrhea in sub-Saharan Africa. Therefore, there is a need to encourage the remaining countries to introduce the vaccine to their routine national immunization programs.

Immunogenicity of four doses of oral poliovirus vaccine when co-administered with the human neonatal rotavirus vaccine (RV3-BB)

BACKGROUND

The RV3-BB human neonatal rotavirus vaccine was developed to provide protection from severe rotavirus disease from birth. The aim of this study was to investigate the potential for mutual interference in the immunogenicity of oral polio vaccine (OPV) and RV3-BB.

METHODS

A randomized, placebo-controlled trial involving 1649 participants was conducted from January 2013 to July 2016 in Central Java and Yogyakarta, Indonesia. Participants received three doses of oral RV3-BB, with the first dose given at 0-5 days (neonatal schedule) or ~8 weeks (infant schedule), or placebo. Two sub-studies assessed the immunogenicity of RV3-BB when co-administered with either trivalent OPV (OPV group, n = 282) or inactivated polio vaccine (IPV group, n = 333). Serum samples were tested for antibodies to poliovirus strains 1, 2 and 3 by neutralization assays following doses 1 and 4 of OPV.

RESULTS

Sero-protective rates to poliovirus type 1, 2 or 3 were similar (range 0.96-1.00) after four doses of OPV co-administered with RV3-BB compared with placebo. Serum IgA responses to RV3-BB were similar when co-administered with either OPV or IPV (difference in proportions OPV vs IPV: sIgA responses; neonatal schedule 0.01, 95% CI -0.12 to 0.14; p = 0.847; infant schedule -0.10, 95% CI -0.21 to -0.001; p = 0.046: sIgA GMT ratio: neonatal schedule 1.23, 95% CI 0.71-2.14, p = 0.463 or infant schedule 1.20, 95% CI 0.74-1.96, p = 0.448).

CONCLUSIONS

The co-administration of OPV with RV3-BB rotavirus vaccine in a birth dose strategy did not reduce the immunogenicity of either vaccine. These findings support the use of a neonatal RV3-BB vaccine where either OPV or IPV is used in the routine vaccination schedule.

Rotavirus prevalence and seasonal distribution post vaccine introduction in Nairobi county Kenya

Rotaviruses are one of the leading etiological agents of gastroenteritis in young children, for which a monovalent G1P(8) vaccine has been provided for free in Kenyan since July 2014. The main objective was to estimate the post vaccine prevalence and seasonal distribution of rotavirus diarrhea in children less than 5 years in Nairobi County, Kenya. Rotavirus positive samples were collected from children below 5 years of age in two hospitals within Nairobi County where vaccination status was card-confirmed. The children were examined and the demographic and clinical profiles of the children were recorded. Fecal specimens were analyzed for rotavirus antigen using an ELISA kit, followed by characterization by PAGE. Out of the total 323 samples, 49 had detectable rotavirus infection, representing 15.2% prevalence. Age distribution of rotavirus prevalence was as follows: ≤ 6 months-8.5%, 7-12 months-27.4%, 13-24 months - 41.4%, 25-36 months - 16.4% while 36-65 months had 6.3%. Rotavirus diarrhea was more common in wet and cold months of the year, the highest prevalence being observed in August (24.5%), 12.3% in both July and March, while April scored a prevalence of 10.2%. Out of the 49 rotavirus positive children, 48 had vomiting and abdominal cramps while all had fever and watery stool. The prevalence of Rotaviral diarrhea in children less than 5 years in Nairobi County Kenya has greatly reduced following the vaccine introduction and is more common during the wet and cold seasons of the year.

Identifying signatures of the impact of rotavirus vaccines on hospitalizations using sentinel surveillance data from Latin American countries

BACKGROUND

Passive surveillance data are often the only available source of data that can be used to evaluate the population-level impact of vaccination, but such data often suffer from important limitations such as changes in surveillance efforts. This study provides an example of how to identify important signatures of rotavirus vaccine impact, including evaluating the overall effectiveness and changes in rotavirus seasonal dynamics.

METHODS

We used data from a standardized sentinel rotavirus surveillance network in six Latin American countries (Bolivia, El Salvador, Guatemala, Honduras, Paraguay, and Venezuela) from 2004 to 2017. A random-effects model was used to evaluate changes in the proportion of rotavirus-associated hospitalizations following vaccine introduction. Harmonic regression models were used to estimate vaccine impact on the number of rotavirus hospitalizations, controlling for trends in rotavirus-negative cases. Changes to rotavirus seasonality were evaluated using center of gravity analysis, wavelet analysis, and harmonic regression.

RESULTS

All countries observed declines in the proportion of rotavirus-positive acute diarrhea samples with a mean reduction of 16% (95% confidence interval: 10-22%). We estimate that each 10% increase in vaccine coverage was associated with declines in the number of rotavirus-positive cases, ranging from 4.3% (1.3-7.2%) in Honduras to 21.4% (16.8-25.9%) in Venezuela. The strength of the seasonal peak in rotavirus incidence became smaller after vaccine introduction in Guatemala, Honduras, and Venezuela. Seasonal peaks also shifted later in the surveillance year, especially in higher-mortality countries.

CONCLUSIONS

The combination of methods we applied have different strengths that allow us to identify common signatures of rotavirus vaccine impact.

A Meta-analysis Assessing Diarrhea and Pneumonia in HIV-Exposed Uninfected Compared With HIV-Unexposed Uninfected Infants and Children

OBJECTIVE

Previous studies have demonstrated that HIV-exposed uninfected (HEU) infants and children experience morbidity and mortality at rates exceeding those of their HIV-unexposed uninfected (HUU) counterparts. We sought to summarize the association between HEU vs. HUU infants and children for the outcomes of diarrhea and pneumonia.

DESIGN

Meta-analysis.

METHODS

We reviewed studies comparing infants and children in the 2 groups for these infectious disease outcomes, in any setting, from 1993 to 2018 from 6 databases.

RESULTS

We included 12 studies, and 17,955 subjects total [n = 5074 (28.3%) HEU and n = 12,881 (71.7%) HUU]. Random-effects models showed HEU infants and children had a 20% increase in the relative risk of acute diarrhea and a 30% increase in the relative risk of pneumonia when compared with their HUU counterparts. When stratifying by time since birth, we showed that HEU vs. HUU children had a 50% and 70% increased risk of diarrhea and pneumonia, respectively, in the first 6 months of life.

CONCLUSIONS

We show an increased risk of diarrhea and pneumonia for HEU vs. HUU infants and children. Although we acknowledge, and commend, the immense public health success of prevention of mother-to-child transmission, we now have an enlarging population of children that seem to be vulnerable to not only death, but increased morbidity. We need to turn our attention to understanding the underlying mechanism and designing effective public health solutions. Further longitudinal research is needed to elucidate possible underlying immunological and/or sociological mechanisms that explain these differences in morbidity.

Heterogeneous susceptibility to rotavirus infection and gastroenteritis in two birth cohort studies: Parameter estimation and epidemiological implications

Cohort studies, randomized trials, and post-licensure studies have reported reduced natural and vaccine-derived protection against rotavirus gastroenteritis (RVGE) in low- and middle-income countries. While susceptibility of children to rotavirus is known to vary within and between settings, implications for estimation of immune protection are not well understood. We sought to re-estimate naturally-acquired protection against rotavirus infection and RVGE, and to understand how differences in susceptibility among children impacted estimates. We re-analyzed data from studies conducted in Mexico City, Mexico and Vellore, India. Cumulatively, 573 rotavirus-unvaccinated children experienced 1418 rotavirus infections and 371 episodes of RVGE over 17,636 child-months. We developed a model that characterized susceptibility to rotavirus infection and RVGE among children, accounting for aspects of the natural history of rotavirus and differences in transmission rates between settings. We tested whether model-generated susceptibility measurements were associated with demographic and anthropometric factors, and with the severity of RVGE symptoms. We identified greater variation in susceptibility to rotavirus infection and RVGE in Vellore than in Mexico City. In both cohorts, susceptibility to rotavirus infection and RVGE were associated with male sex, lower birth weight, lower maternal education, and having fewer siblings; within Vellore, susceptibility was also associated with lower socioeconomic status. Children who were more susceptible to rotavirus also experienced higher rates of rotavirus-negative diarrhea, and higher risk of moderate-to-severe symptoms when experiencing RVGE. Simulations suggested that discrepant estimates of naturally-acquired immunity against RVGE can be attributed, in part, to between-setting differences in susceptibility of children, but result primarily from the interaction of transmission rates with age-dependent risk for infections to cause RVGE. We found that more children in Vellore than in Mexico City belong to a high-risk group for rotavirus infection and RVGE, and demonstrate that unmeasured individual- and age-dependent susceptibility may influence estimates of naturally-acquired immune protection against RVGE.

Differences in susceptibility can help explain why some individuals, and not others, acquire infection and exhibit symptoms when exposed to infectious disease agents. However, it is difficult to distinguish between differences in susceptibility versus exposure in epidemiological studies. We developed a modeling approach to distinguish transmission intensity and susceptibility in data from cohort studies of rotavirus infection among children in Mexico City, Mexico, and Vellore, India, and evaluated how these factors may have contributed to differences in estimates of naturally-acquired immune protection between the studies. Given the same exposure, more children were at high risk of acquiring rotavirus infection, and of experiencing gastroenteritis when infected, in Vellore than in Mexico City. The probability of belonging to this high-risk stratum was associated with well-known individual factors such as lower socioeconomic status, lower birth weight, and incidence of diarrhea due to other causes. We also found the risk for rotavirus infections to cause symptoms declined with age, independent of acquired immunity. These findings can, in part, account for estimates of lower protective efficacy of acquired immunity against rotavirus gastroenteritis in high-incidence settings, mirroring estimates of reduced effectiveness of live oral rotavirus vaccines in low- and middle-income countries.

Impact of Rotavirus Vaccine Introduction and Postintroduction Etiology of Diarrhea Requiring Hospital Admission in Haydom, Tanzania, a Rural African Setting

Background

No data are available on the etiology of diarrhea requiring hospitalization after rotavirus vaccine introduction in Africa. The monovalent rotavirus vaccine was introduced in Tanzania on 1 January 2013. We performed a vaccine impact and effectiveness study as well as a quantitative polymerase chain reaction (qPCR)–based etiology study at a rural Tanzanian hospital.

Methods

We obtained data on admissions among children <5 years to Haydom Lutheran Hospital between 1 January 2010 and 31 December 2015 and estimated the impact of vaccine introduction on all-cause diarrhea admissions. We then performed a vaccine effectiveness study using the test-negative design. Finally, we tested diarrheal specimens during 2015 by qPCR for a broad range of enteropathogens and calculated pathogen-specific attributable fractions (AFs).

Results

Vaccine introduction was associated with a 44.9% (95% confidence interval [CI], 17.6%–97.4%) reduction in diarrhea admissions in 2015, as well as delay of the rotavirus season. The effectiveness of 2 doses of vaccine was 74.8% (95% CI, –8.2% to 94.1%) using an enzyme immunoassay–based case definition and 85.1% (95% CI, 26.5%–97.0%) using a qPCR-based case definition. Among 146 children enrolled in 2015, rotavirus remained the leading etiology of diarrhea requiring hospitalization (AF, 25.8% [95% CI, 24.4%–26.7%]), followed by heat-stable enterotoxin-producing Escherichia coli (AF, 18.4% [95% CI, 12.9%–21.9%]), Shigella/enteroinvasive E. coli (AF, 14.5% [95% CI, 10.2%–22.8%]), and Cryptosporidium (AF, 7.9% [95% CI, 6.2%–9.3%]).

Conclusions

Despite the clear impact of vaccine introduction in this setting, rotavirus remained the leading etiology of diarrhea requiring hospitalization. Further efforts to maximize vaccine coverage and improve vaccine performance in these settings are warranted.

Prevalence and molecular typing of rotavirus in children with acute diarrhoea in Northeastern Colombia

After the introduction of the rotavirus vaccine, the number of rotavirus-associated deaths and the predicted annual rotavirus detection rate had slightly declined worldwide. Taking in account that in Colombia, Rotarix vaccine was introduced in 2009, the purpose of this study was to evaluate the presence of rotavirus A in children under five years who were treated for acute diarrhoea in Bucaramanga, Colombia and, moreover, to determine the genotypes of rotavirus present in those children. We performed an analytical cross-sectional study of rotavirus A in faecal samples from children up to five years of age. Stool samples were screened for rotavirus A using a lateral-flow immunochromatographic assay and confirmed using a VP6 sandwich ELISA. Genotyping of rotavirus A-positive samples was performed by PCR and sequencing of VP7 and VP4 genes. The overall prevalence of rotavirus was 30.53% (95% confidence interval [CI] 21.2 - 39.7). Most of the children with rotavirus (86.2%) had received two doses of the rotavirus vaccine. G3 strains accounted for the vast majority of cases (82.8%), followed by G12 strains (13.8%) and G3/G9 coinfections (3.4%). Among the P genotypes, P[8] was the most prevalent (69%), followed by P[9] (31%). The most common G[P] genotype combination was G3P[8], followed by G3P[9]. The main finding in this study was that rotavirus, in a Colombian region, is still an important pathogen in children under five years old, previously vaccinated. The results showed that different factors, such as kindergarten attendance, could explain the epidemiology and transmission of rotavirus in Bucaramanga.

Evolution of P[8], P[4], and P[6] VP8* genes of human rotaviruses globally reported during 1974 and 2017: possible implications for rotavirus vaccines in development

Non-replicating parenteral rotavirus (RV) vaccine candidates are in development in an attempt to overcome the lower efficacy and effectiveness of oral RV vaccines in low-income countries. One of the leading candidates is a truncated recombinant VP8* protein, expressed in Escherichia coli from original sequences of the prototype RV genotypes P[8], P[4], or P[6] isolated before 1983. Since VP8* is highly variable, it was considered useful to examine the evolutionary changes of RV strains reported worldwide over time in relation to the three P2-VP8 vaccine strains. Here, we retrieved from the GenBank 6,366 RV VP8* gene sequences of P[8], P[4], or P[6] strains isolated between 1974 and 2017, in 77 countries, and compared them with those of the three P2-VP8 vaccine strains: Wa (USA, 1974, G1P[8]), DS-1 (USA, 1976, G2P[4]), and 1076 (Sweden, 1983, G2P[6]). Phylogenetic analysis showed that 94.9% (4,328/4,560), 99.8% (1,141/1,143), and 100% (663/663) of the P[8], P[4], and P[6] strains, respectively, reported globally between 1974 and 2018 belong to non-vaccine lineages. These P[8], P[4], and P[6] RV strains have a mean of 9%, 5%, and 6% amino acid difference from the corresponding vaccine strains. Additionally, in the USA, the mean percentage difference between all the P[8] RV strains and the original Wa strain increased over time: 4% (during 1974-1980), 5% (1988-1991), and 9% (2005-2013). Our analysis substantiated high evolutionary changes in VP8* of the P[8], P[4], and P[6] major RV strains and their increasing variations from the candidate subunit vaccine strains over time. These findings may have implications for the development of new RV vaccines.

Rotavirus vaccine impact assessment surveillance in India: protocol and methods

INTRODUCTION

Rotavirus infection accounts for 39% of under-five diarrhoeal deaths globally and 22% of these deaths occur in India. Introduction of rotavirus vaccine in a national immunisation programme is considered to be the most effective intervention in preventing severe rotavirus disease. In 2016, India introduced an indigenous rotavirus vaccine (Rotavac) into the Universal Immunisation Programme in a phased manner. This paper describes the protocol for surveillance to monitor the performance of rotavirus vaccine following its introduction into the routine childhood immunisation programme.

METHODS

An active surveillance system was established to identify acute gastroenteritis cases among children less than 5 years of age. For all children enrolled at sentinel sites, case reporting forms are completed and a copy of vaccination record and a stool specimen obtained. The forms and specimens are sent to the referral laboratory for data entry, analysis, testing and storage. Data from sentinel sites in states that have introduced rotavirus vaccine into their routine immunisation schedule will be used to determine rotavirus vaccine impact and effectiveness.

ETHICS AND DISSEMINATION

The Institutional Review Board of Christian Medical College, Vellore, and all the site institutional ethics committees approved the project. Results will be disseminated in peer-reviewed journals and with stakeholders of the universal immunisation programme in India.

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.

Rates of hospitalization and death for all-cause and rotavirus acute gastroenteritis before rotavirus vaccine introduction in Kenya, 2010-2013

Background

Rotavirus vaccine was introduced in Kenya immunization program in July 2014. Pre-vaccine disease burden estimates are important for assessing vaccine impact.

Methods

Children with acute gastroenteritis (AGE) (≥3 loose stools and/or ≥ 1 episode of unexplained vomiting followed by loose stool within a 24-h period), hospitalized in Siaya County Referral Hospital (SCRH) from January 2010 through December 2013 were enrolled. Stool specimens were tested for rotavirus (RV) using an enzyme immunoassay (EIA). Hospitalization rates were calculated using person-years of observation (PYO) from the Health Demographic Surveillance System (HDSS) as a denominator, while adjusting for healthcare utilization at household level and proportion of stool specimen collected from patients who met the case definition at the surveillance hospital. Mortality rates were calculated using PYO as the denominator and number of deaths estimated using total deaths in the HDSS, proportion of deaths attributed to diarrhoea by verbal autopsy (VA) and percent positive for rotavirus AGE (RVAGE) hospitalizations.

Results

Of 7760 all-cause hospitalizations among children < 5 years of age, 3793 (49%) were included in the analysis. Of these, 21% (805) had AGE; RV was detected in 143 (26%) of 541 stools tested. Among children < 5 years, the estimated hospitalization rates per 100,000 PYO for AGE and RVAGE were 2413 and 429, respectively. Mortality rate associated with AGE and RVAGE were 176 and 45 per 100,000 PYO, respectively.

Conclusion

AGE and RVAGE caused substantial health care burden (hospitalizations and deaths) before rotavirus vaccine introduction in Kenya.

RA-839, a selective agonist of Nrf2/ARE pathway, exerts potent anti-rotaviral efficacy in vitro

Acute watery diarrhea due to Rotavirus (RV) infection is associated with high infantile morbidity and mortality in countries with compromised socio-economic backgrounds. Although showing promising trends in developed countries, the efficacy of currently licensed RV vaccines is sub-optimal in socio-economically poor settings with high disease burden. Currently, there are no approved anti-rotaviral drugs adjunct to classical vaccination program. Interestingly, dissecting host-rotavirus interaction has yielded novel, non-mutable host determinants which can be subjected to interventions by selective small molecules. The present study was undertaken to evaluate the anti-RV potential of RA-839, a recently discovered small molecule with potent and highly selective agonistic activity towards cellular redox stress-sensitive Nuclear factor erytheroid-derived-2-like 2 (Nrf2)/Antioxidant Response Element (ARE) pathway. In vitro studies revealed that RA-839 inhibits RV RNA and protein expression, viroplasm formation, yield of virion progeny and virus-induced cytopathy independent of RV strains, RV-permissive cell lines and without bystander cytotoxicity. Anti-RV potency of RA-839 was subsequently identified to be independent of stochastic Interferon (IFN) stimulation but to be dependent on RA-839's ability to stimulate Nrf2/ARE signaling. Interestingly, anti-rotaviral effects of RA-839 were also mimicked by 2-Cyano-3, 12-dioxo-oleana-1, 9(11)-dien-28-oic acid methyl ester (CDDO-Me) and Hemin, two classical pharmacological activators of Nrf2/ARE pathway. Overall, this study highlights that RA-839 is a potent antagonist of RV propagation in vitro and can be developed as anti-rotaviral therapeutics.

Therapeutics and Immunoprophylaxis Against Noroviruses and Rotaviruses: The Past, Present, and Future

Background:

Noroviruses and rotaviruses are important viral etiologies of severe gastroenteritis. Noroviruses are the primary cause of nonbacterial diarrheal outbreaks in humans, whilst rotaviruses are a major cause of childhood diarrhea. Although both enteric pathogens substantially impact human health and economies, there are no approved drugs against noroviruses and rotaviruses so far. On the other hand, whilst the currently licensed rotavirus vaccines have been successfully implemented in over 100 countries, the most advanced norovirus vaccine has recently completed phase-I and II trials.

Methods:

We performed a structured search of bibliographic databases for peer-reviewed research litera-ture on advances in the fields of norovirus and rotavirus therapeutics and immunoprophylaxis.

Results:

Technological advances coupled with a proper understanding of viral morphology and replication over the past decade has facilitated pioneering research on therapeutics and immunoprophylaxis against noroviruses and rotaviruses, with promising outcomes in human clinical trials of some of the drugs and vaccines. This review focuses on the various developments in the fields of norovirus and rotavirus thera-peutics and immunoprophylaxis, such as potential antiviral drug molecules, passive immunotherapies (oral human immunoglobulins, egg yolk and bovine colostral antibodies, llama-derived nanobodies, and anti-bodies expressed in probiotics, plants, rice grains and insect larvae), immune system modulators, probiot-ics, phytochemicals and other biological substances such as bovine milk proteins, therapeutic nanoparti-cles, hydrogels and viscogens, conventional viral vaccines (live and inactivated whole virus vaccines), and genetically engineered viral vaccines (reassortant viral particles, virus-like particles (VLPs) and other sub-unit recombinant vaccines including multi-valent viral vaccines, edible plant vaccines, and encapsulated viral particles).

Conclusions:

This review provides important insights into the various approaches to therapeutics and im-munoprophylaxis against noroviruses and rotaviruses..

Variation in Childhood Diarrheal Morbidity and Mortality in Africa, 2000-2015

BACKGROUND

Diarrheal diseases are the third leading cause of disease and death in children younger than 5 years of age in Africa and were responsible for an estimated 30 million cases of severe diarrhea (95% credible interval, 27 million to 33 million) and 330,000 deaths (95% credible interval, 270,000 to 380,000) in 2015. The development of targeted approaches to address this burden has been hampered by a paucity of comprehensive, fine-scale estimates of diarrhea-related disease and death among and within countries.

METHODS

We produced annual estimates of the prevalence and incidence of diarrhea and diarrhea-related mortality with high geographic detail (5 km2) across Africa from 2000 through 2015. Estimates were created with the use of Bayesian geostatistical techniques and were calibrated to the results from the Global Burden of Diseases, Injuries, and Risk Factors Study 2016.

RESULTS

The results revealed geographic inequality with regard to diarrhea risk in Africa. Of the estimated 330,000 childhood deaths that were attributable to diarrhea in 2015, more than 50% occurred in 55 of the 782 first-level administrative subdivisions (e.g., states). In 2015, mortality rates among first-level administrative subdivisions in Nigeria differed by up to a factor of 6. The case fatality rates were highly varied at the national level across Africa, with the highest values observed in Benin, Lesotho, Mali, Nigeria, and Sierra Leone.

CONCLUSIONS

Our findings showed concentrated areas of diarrheal disease and diarrhea-related death in countries that had a consistently high burden as well as in countries that had considerable national-level reductions in diarrhea burden. (Funded by the Bill and Melinda Gates Foundation.).

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: Genetics, pathogenesis and vaccine advances

Since its discovery 40 years ago, rotavirus (RV) is considered to be a major cause of infant and childhood morbidity and mortality particularly in developing countries. Nearly every child in the world under 5 years of age is at the risk of RV infection. It is estimated that 90% of RV-associated mortalities occur in developing countries of Africa and Asia. Two live oral vaccines, RotaTeq (RV5, Merck) and Rotarix (RV1, GlaxoSmithKline) have been successfully deployed to scale down the disease burden in Europe and America, but they are less effective in Africa and Asia. In April 2009, the World Health Organization recommended the inclusion of RV vaccination in national immunization programs of all countries with great emphasis in developing countries. To date, 86 countries have included RV vaccines into their national immunization programs including 41 Global Alliance for Vaccines and Immunization eligible countries. The predominant RV genotypes circulating all over the world are G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8], while G12[P6] and G12[P8] are emerging genotypes. On account of the segmented genome, RV shows an enormous genetic diversity that leads to the evolution of new genotypes that can influence the efficacy of current vaccines. The current need is for a global RV surveillance program to monitor the prevalence and antigenic variability of new genotypes to formulate future vaccine development planning. In this review, we will summarize the previous and recent insights into RV structure, classification, and epidemiology and current status of RV vaccination around the globe and will also cover the status of RV research and vaccine policy in Pakistan.

Using surveillance and economic data to make informed decisions about rotavirus vaccine introduction

While rotavirus vaccines are available, safe, and effective, many countries are not yet widely using these vaccines. Surveillance for rotavirus disease and potential vaccine adverse events is critical for country decision making about rotavirus vaccine. This special issue shares rotavirus and intussusception disease surveillance data and rotavirus vaccine cost-effectiveness analyses from countries that have yet to introduce rotavirus vaccines into their routine infant immunization programs. The studies highlight the substantial burden of rotavirus disease and the cost-effectiveness of rotavirus vaccine in a broad set of countries without rotavirus vaccine in their routine immunization programs.

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.

Effects of geographic and economic heterogeneity on the burden of rotavirus diarrhea and the impact and cost-effectiveness of vaccination in Pakistan

Globally, rotavirus is a leading cause of childhood diarrhea and related mortality. Although rotavirus vaccination has been introduced in many countries worldwide, there are numerous low- to middle-income countries that have not yet introduced. Pakistan is one of the countries with the highest number of rotavirus deaths in children under five years. Although rotavirus infection is almost universal among children, mortality is often a result of poor nutrition and lack of access to health care and other aspects of poverty. We assess the impact and cost-effectiveness of introducing childhood rotavirus vaccination in Pakistan. We use household data from the 2012-2013 Demographic Health survey in Pakistan to estimate heterogeneity in rotavirus mortality risk, vaccination benefits, and cost-effectiveness across geographic and economic groups. We estimate two-dose rotavirus vaccination coverage that would be distributed through a routine vaccination program. In addition, we estimate rotavirus mortality (burden), and other measures of vaccine cost-effectiveness and impact by subpopulations of children aggregated by region and economic status. Results indicate that the highest estimated regional rotavirus burden is in Sindh (3.3 rotavirus deaths/1000 births) and Balochistan (3.1 rotavirus deaths/1000 births), which also have the lowest estimated vaccination coverage, particularly for children living in the poorest households. In Pakistan, introduction could prevent 3061 deaths per year with current routine immunization patterns at an estimated $279/DALY averted. Increases in coverage to match the region with highest coverage (Islamabad) could prevent an additional 1648 deaths per year. Vaccination of children in the highest risk regions could result in a fourfold mortality reduction as compared to low risk children, and children in the poorest households have a three to four times greater mortality reduction benefit than the richest. Based on the analysis presented here, the benefits and cost-effectiveness of rotavirus vaccination can be maximized by reaching economically and geographically vulnerable children.

Preventive Effect of a Synbiotic Combination of Galacto- and Fructooligosaccharides Mixture With Bifidobacterium breve M-16V in a Model of Multiple Rotavirus Infections

Rotavirus (RV) causes morbidity and mortality among infants worldwide, and there is evidence that probiotics and prebiotics can have a positive influence against infective processes such as that due to RV. The aim of this study was to evidence a preventive role of one prebiotic mixture (of short-chain galactooligosaccharide/long-chain fructooligosaccharide), the probiotic Bifidobacterium breve M-16V and the combination of the prebiotic and the probiotic, as a synbiotic, in a suckling rat double-RV infection model. Hyperimmune bovine colostrum was used as protection control. The first infection was induced with RV SA11 and the second one with EDIM. Clinical variables and immune response were evaluated after both infections. Dietary interventions ameliorated clinical symptoms after the first infection. The prebiotic and the synbiotic significantly reduced viral shedding after the first infection, but all the interventions showed higher viral load than in the RV group after the second infection. All interventions modulated ex vivo antibody and cytokine production, gut wash cytokine levels and small intestine gene expression after both infections. In conclusion, a daily supplement of the products tested in this preclinical model is highly effective in preventing RV-induced diarrhea but allowing the boost of the early immune response for a future immune response against reinfection, suggesting that these components may be potential agents for modulating RV infection in infants.

Sustained impact of rotavirus vaccine on rotavirus hospitalisations in Lusaka, Zambia, 2009-2016

BACKGROUND

Monovalent rotavirus vaccine (RV1) was introduced in Lusaka in February 2012 and rolled out countrywide in November 2013 in the routine Expanded Programme on Immunisation and administered at 6 and 10 weeks with no catch up dose. Reported here is the monitoring of rotavirus acute gastroenteritis hospitalisations at the University Teaching Hospital, Lusaka, Zambia as part of efforts to document the impact of rotavirus vaccine.

METHODS

Children <5 years hospitalised for acute gastroenteritis (AGE) from January 2009 to December 2016 were recruited into the rotavirus disease burden active surveillance and had their stools tested for rotavirus by enzyme immunoassay. We compared rotavirus-associated AGE hospitalisations of the pre-vaccine era (2009-2011) with the post-rotavirus vaccine introduction period (2013-2016).

RESULTS

With the increase in RV1 coverage in Lusaka, rotavirus AGE declined significantly from 40% of diarrhoea hospitalisation in the pre-vaccine era to 29% of diarrhoea hospitalisation in the post-vaccine era (p < 0.001) in children <5 years. After a decreasing trend in rotavirus positivity from 2013 to 2015, positivity increased to 37% in 2016. However, the post-vaccine years (2012-2016) saw substantial decline in the number tested (median decline: 34% (range: 20-43%)) and the number of positive results (median decline: 52% (range: 30-65%).

CONCLUSION

A sustained and significant decline in rotavirus AGE hospitalisations was observed in children <5 years since the introduction of RV1 in Lusaka, Zambia. Despite an increase in rotavirus positivity in 2016, the total number of children enrolled and the number of rotavirus positive children remained below baseline. The reason for the increase in rotavirus positivity in 2016 is unknown but could be due to an accumulation of susceptible children and the shifting of disease to children of older age groups. This finding underscores the need for continued monitoring of rotavirus vaccine impact.

Whole-genome sequencing and analyses identify high genetic heterogeneity, diversity and endemicity of rotavirus genotype P[6] strains circulating in Africa

Rotavirus A (RVA) exhibits a wide genotype diversity globally. Little is known about the genetic composition of genotype P[6] from Africa. This study investigated possible evolutionary mechanisms leading to genetic diversity of genotype P[6] VP4 sequences. Phylogenetic analyses on 167 P[6] VP4 full-length sequences were conducted, which included six porcine-origin sequences. Of the 167 sequences, 57 were newly acquired through whole genome sequencing as part of this study. The other 110 sequences were all publicly-available global P[6] VP4 full-length sequences downloaded from GenBank. The strength of association between the phenotypic features and the phylogeny was also determined. A number of reassortment and mixed infections of RVA genotype P[6] strains were observed in this study. Phylogenetic analyses demostrated the extensive genetic diversity that exists among human P[6] strains, porcine-like strains, their concomitant clades/subclades and estimated that P[6] VP4 gene has a higher substitution rate with the mean of 1.05E-3 substitutions/site/year. Further, the phylogenetic analyses indicated that genotype P[6] strains were endemic in Africa, characterised by an extensive genetic diversity and long-time local evolution of the viruses. This was also supported by phylogeographic clustering and G-genotype clustering of the P[6] strains when Bayesian Tip-association Significance testing (BaTS) was applied, clearly supporting that the viruses evolved locally in Africa instead of spatial mixing among different regions. Overall, the results demonstrated that multiple mechanisms such as reassortment events, various mutations and possibly interspecies transmission account for the enormous diversity of genotype P[6] strains in Africa. These findings highlight the need for continued global surveillance of rotavirus diversity.

Impact of rotavirus vaccination on rotavirus hospitalisation rates among a resource-limited rural population in Mbita, Western Kenya

OBJECTIVES

A two-dose oral monovalent rotavirus vaccine (RV1) was introduced into the Kenyan National Immunization Program in July 2014. We assessed trends in hospitalisation for rotavirus-specific acute gastroenteritis (AGE) and strain distribution among children <5 years in a rural, resource-limited setting in Kenya before and after the nationwide implementation of the vaccine.

METHODS

Data on rotavirus AGE and strain distribution were derived from a 5-year hospital-based surveillance. We compared rotavirus-related hospitalisations and strain distribution in the 2-year post-vaccine period with the 3-year pre-vaccine baseline. Vaccine administrative data from the Unit of Vaccines and Immunization Services (UVIS) for Mbita sub-county were used to estimate rotavirus immunisation coverage in the study area.

RESULTS

We observed a 48% (95% CI: 27-64%) overall decline in rotavirus-related hospitalisations among children aged <5 years in the post-vaccine period. Coverage with the last dose of rotavirus vaccine increased from 51% in year 1% to 72% in year 2 of the vaccine implementation. Concurrently, reductions in rotavirus hospitalisations increased from 40% in the first year to 53% in the second year of vaccine use. The reductions were most pronounced among the vaccine-eligible group, with the proportion of cases in this age group dropping to 14% in post-vaccine years from a high of 51% in the pre-vaccine period. A diversity of rotavirus strains circulated before the introduction of the vaccine with G1P[8] being the most dominant strain. G2P[4] replaced G1P[8] as the dominant strain after the vaccine was introduced.

CONCLUSIONS

Rotavirus vaccination has resulted in a notable decline in hospital admissions for rotavirus infections in a rural resource-limited population in Kenya. This provides early evidence for continued use of rotavirus vaccines in routine childhood immunisations in Kenya. Our data also underscore the need for expanding coverage on second dose so as to maximise the impact of the vaccine.