Monovalent Rotavirus Vaccine Effectiveness Against Rotavirus Hospitalizations Among Children in Zimbabwe

Effectiveness and impact of monovalent rotavirus vaccination in Afghanistan: a test-negative case-control analysis

BACKGROUND

Afghanistan introduced monovalent rotavirus vaccine (Rotarix) into its national immunisation schedule in January, 2018. While post-licensure studies have shown substantial declines in rotavirus gastroenteritis cases and deaths globally, there is little evidence of rotavirus vaccine effectiveness and impact from low-income countries in Asia. We aimed to evaluate the effectiveness of the Rotarix vaccine and the impact of Rotarix vaccine on rotavirus gastroenteritis hospitalisations (ie, hospital admissions) among children younger than 5 years in Afghanistan.

METHODS

We used a test-negative case-control design embedded in an active sentinel surveillance platform to evaluate vaccine effectiveness. Children born on or after Jan 1, 2018, who had documentation of their rotavirus vaccination status and who were admitted for acute gastroenteritis at one of four sentinel hospitals from May, 2018 to December, 2021 were eligible to be included. We used an unconditional logistic regression model to estimate vaccine effectiveness and 95% CIs for a complete series of doses compared with no rotavirus vaccine doses among patients admitted with acute gastroenteritis. Vaccine effectiveness against hospitalisation was calculated as (1 - [odds of being vaccinated in cases] / [odds of being vaccinated in controls]) × 100%. We compared pre-vaccine (2013-15) and post-vaccine (2019-21) surveillance data from two sites to calculate vaccine impact.

FINDINGS

The vaccine effectiveness analysis included 1172 cases and 2173 controls. Approximately 2108 (63·0%) of 3345 cases and controls were male, 1237 (37·0%) were female, and 2171 (65·0%) were aged 6-11 months. Two doses of Rotarix were 45% (95% CI 22-62) effective against rotavirus hospitalisation in children aged 6-59 months, adjusting for age, severity, admission year, and rotavirus season. Rotavirus positivity decreased from 51% pre-vaccine to 39% post-vaccine, resulting in a 39% adjusted reduction in rotavirus positivity among children younger than 5 years admitted with acute gastroenteritis.

INTERPRETATION

Rotarix showed moderate effectiveness in preventing rotavirus gastroenteritis hospitalisations, consistent with findings in other low-income countries. These findings support the continued administration of the rotavirus vaccine in Afghanistan.

FUNDING

Gavi, the Vaccine Alliance.

TRANSLATION

For the Dari translation of the abstract see Supplementary Materials section.

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.

Social and Environmental Determinants of Diarrheal Diseases among Children under Five Years in Epworth Township, Harare

Children five years or younger in low- and middle-income countries (LMICs) are severely affected by diarrheal disease, especially in the sub-Saharan region. Hence, this study aimed at determining the prevalence and determinants of diarrhoea disease among children under 5 years in Epworth Township, Zimbabwe. A descriptive cross-sectional study was conducted at a local clinic in Epworth Township, Harare. A convenience sampling strategy was used to recruit study participants for participation, and 386 children were enrolled in the study. The majority were male children (n = 229; 59.3%), whereas there were more female caregivers (n = 370; 95.9%) than male caregivers (n = 16; 4.1%). The prevalence of diarrhoea disease in the study was 25.1%. The determinants associated with diarrhoea were being partially vaccinated (AOR 2.38, CI: 95% 2.80-8.22), collecting water more than 1 kilometre from a household (AOR 4.55; CI: 95% 2.10-9.85), and using untreated water (AOR 6.22; CI: 95% 2.13-18.20). The age of the caregiver (being older than 21) and using a clean water container (AOR 0.05; CI: 95% 0.02-0.13) were protective factors. Provision of primary health care, especially the prevention of a disease through immunization and rendering environmental health services, could reduce the prevalence of diarrhoea in disadvantaged townships.

Rotavirus infections and their genotype distribution in Rwanda before and after the introduction of rotavirus vaccination

Rotavirus vaccination has reduced mortality and hospital admissions due to rotavirus diarrhoea, but its effect on rotavirus infections and the impact of rotavirus genotypes are still unclear. Real-time PCR was used to detect rotavirus and other pathogens in faeces samples from children below five years of age with acute diarrhoea, collected before (n = 827) and after (n = 807, 92% vaccinated) the introduction of vaccination in Rwanda in 2012. Rotavirus was genotyped by targeting VP7 to identify G1, G2, G3, G4, G9 and G12 and VP4 to identify P[4], P[6] and P[8]. In vaccinated children, rotavirus infections were rarer (34% vs. 47%) below 12 months of age, severe dehydration was less frequent, and rotavirus was more often found as a co-infecting agent. (79% vs 67%, p = 0.004). Norovirus genogroup II, astrovirus, and sapovirus were significantly more often detected in vaccinated children. The predominant rotavirus genotypes were G2P[4] and G12P[6] in 2009-2010 (50% and 12%), G9P[8] and G1P[8] in 2011-2012 (51% and 22%), and G12P[8] in 2014-2015 (63%). Rotavirus vaccination in Rwanda has reduced the severity of rotavirus gastroenteritis and rotavirus infection frequency during the first year of life. Rotavirus infections were frequent in vaccinated children with diarrhoea, often as co-pathogen. Rotavirus genotype changes might be unrelated to vaccination because shifts were observed also before its introduction.

Cost-effectiveness of rotavirus vaccination in Mozambique

Introduction

Rotavirus is one of the most common cause of severe gastroenteritis in children, with the largest mortality burden in low- and middle-income countries. To prevent rotavirus gastroenteritis, Mozambique introduced ROTARIX® vaccine in 2015, however, its cost-effectiveness has never been established in the country. In 2018, additional vaccines became available globally. This study estimates the cost-effectiveness of the recently introduced ROTARIX in Mozambique and compares the cost-effectiveness of ROTARIX®, ROTAVAC®, and ROTASIIL® to inform future use.

Methods

We used a decision-support model to calculate the potential cost-effectiveness of vaccination with ROTARIX compared to no vaccination over a five-year period (2016–2020) and to compare the cost-effectiveness of ROTARIX, ROTAVAC, and ROTASIIL to no vaccination and to each other over a ten-year period (2021–2030). The primary outcome was the incremental cost per disability-adjusted life-year (DALY) averted from a government perspective. We assessed uncertainty through sensitivity analyses.

Results

From 2016 to 2020, we estimate the vaccine program with ROTARIX cost US$12.3 million, prevented 4,628 deaths, and averted US$3.1 million in healthcare costs. The cost per DALY averted was US$70. From 2021 to 2030, we estimate all three vaccines could prevent 9,000 deaths and avert US$7.8 million in healthcare costs. With Global Alliance for Vaccines and Immunization (Gavi) support, ROTARIX would have the lowest vaccine program cost (US$31 million) and 98 % probability of being cost-effective at a willingness-to-pay threshold of 0.5x GDP per capita. Without Gavi support, ROTASIIL would have the lowest vaccine program cost (US$75.8 million) and 30 % probability of being cost-effective at the same threshold.

Conclusion

ROTARIX vaccination had a substantial public health impact in Mozambique between 2016 and 2020. ROTARIX is currently estimated to be the most cost-effective product, but the choice of vaccine should be re-evaluated as more evidence emerges on the price, incremental delivery cost, wastage, and impact associated with each of the different rotavirus vaccines.

Community-level interventions for mitigating the risk of waterborne diarrheal diseases: a systematic review

BACKGROUND

Waterborne diarrhea diseases are among the leading causes of morbidity and mortality globally. These diseases can be mitigated by implementing various interventions. We reviewed the literature to identify available interventions to mitigate the risk of waterborne diarrheal diseases.

METHODS

We conducted a systematic database review of CINAHL (Cumulative Index to Nursing and Allied Health Literature), PubMed, Web of Science Core Collection, Cochrane library, Scopus, African Index Medicus (AIM), and LILACS (Latin American and Caribbean Health Sciences Literature). Our search was limited to articles published between 2009 and 2020. We conducted the review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement checklist. The identified studies were qualitatively synthesized.

RESULTS

Our initial search returned 28 773 articles of which 56 studies met the inclusion criteria. The included studies reported interventions, including vaccines for rotavirus disease (monovalent, pentavalent, and Lanzhou lamb vaccine); enhanced water filtration for preventing cryptosporidiosis, Vi polysaccharide for typhoid; cholera 2-dose vaccines, water supply, water treatment and safe storage, household disinfection, and hygiene promotion for controlling cholera outbreaks.

CONCLUSION

We retrieved few studies on interventions against waterborne diarrheal diseases in low-income countries. Interventions must be specific to each type of waterborne diarrheal disease to be effective. Stakeholders must ensure collaboration in providing and implementing multiple interventions for the best outcomes.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020190411 .

Effectiveness of Monovalent Rotavirus Vaccine in Mozambique, a Country with a High Burden of Chronic Malnutrition

Mozambique introduced monovalent rotavirus vaccine (Rotarix®) in September 2015. We evaluated the effectiveness of Rotarix® under conditions of routine use in Mozambican children hospitalized with acute gastroenteritis (AGE). A test negative case-control analysis was performed on data collected during 2017−2019 from children <5 years old, admitted with AGE in seven sentinel hospital sites in Mozambique. Adjusted VE was calculated for ≥1 dose of vaccine vs. zero doses using unconditional logistic regression, where VE = (1 − aOR) × 100%. VE estimates were stratified by age group, AGE severity, malnutrition, and genotype. Among 689 children eligible for analysis, 23.7% were rotavirus positive (cases) and 76.3% were negative (controls). The adjusted VE of ≥1 dose in children aged 6−11 months was 52.0% (95% CI, −11, 79), and −24.0% (95% CI, −459, 62) among children aged 12−23 months. Estimated VE was lower in stunted than non-stunted children (14% (95% CI, −138, 66) vs. 59% (95% CI, −125, 91)). Rotavirus vaccination appeared moderately effective against rotavirus gastroenteritis hospitalization in young Mozambican children. VE point estimates were lower in older and stunted children, although confidence intervals were wide and overlapped across strata. These findings provide additional evidence for other high-mortality countries considering rotavirus vaccine introduction.

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

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

Rotavirus Infection, Illness, and Vaccine Performance in Malnourished Children: A Review of the Literature

Live, oral rotavirus vaccines are more effective at preventing rotavirus disease in countries with low child mortality compared with high child mortality. Among several hypotheses, poorer protection in malnourished children, who are more prevalent in countries with high child mortality, may partially explain this difference. We conducted a literature search to identify articles with a laboratory-confirmed rotavirus endpoint that evaluated differences by malnutrition status in rotavirus vaccine effectiveness and vaccine efficacy (VE) or the prevalence of rotavirus infection or illness among children <5 years old. We identified 7 analyses from 11 countries published from 2007 to 2019 that stratified rotavirus VE by malnutrition status. Among well-nourished children, VE point estimates ranged from 71% to 84% in observational studies and 26% to 61% in clinical trials. Among malnourished children, they ranged from -28% to 45% in observational studies and -3% to 61% in clinical trials. The relative difference between VE in well-nourished and malnourished children by length-for-age ranged from 37% to 64%, by weight-for-age ranged from 0% to 107%, and by weight-for-height ranged from -65% to 137%. We identified 3 cohort and 6 cross-sectional studies of natural rotavirus infection and illness and none reported that malnourished children were more susceptible to rotavirus infection or illness than well-nourished children. Overall, rotavirus vaccines may offer less protection to children with malnutrition than well-nourished children. As malnourished children often have worse outcomes from diarrhea, high rotavirus vaccine coverage and a better understanding of the performance of oral rotavirus vaccines in this population is important, though our finding that malnourished children may be less susceptible to rotavirus provides important context and information for vaccine evaluation design.

Association of Rotavirus Vaccines With Reduction in Rotavirus Gastroenteritis in Children Younger Than 5 Years: A Systematic Review and Meta-analysis of Randomized Clinical Trials and Observational Studies

IMPORTANCE

Rotavirus vaccines have been introduced worldwide, and the clinical association of different rotavirus vaccines with reduction in rotavirus gastroenteritis (RVGE) after introduction are noteworthy.

OBJECTIVE

To evaluate the comparative benefit, risk, and immunogenicity of different rotavirus vaccines by synthesizing randomized clinical trials (RCTs) and observational studies.

DATA SOURCES

Relevant studies published in 4 databases: Embase, PubMed, the Cochrane Library, and Web of Science were searched until July 1, 2020, using search terms including "rotavirus" and "vaccin*."

STUDY SELECTION

Randomized clinical trials and cohort and case-control studies involving more than 100 children younger than 5 years that reported the effectiveness, safety, or immunogenicity of rotavirus vaccines were included.

DATA EXTRACTION AND SYNTHESIS

A random-effects model was used to calculate relative risks (RRs), odds ratios (ORs), risk differences, and 95% CIs. Adjusted indirect treatment comparison was performed to assess the differences in the protection of Rotarix and RotaTeq.

MAIN OUTCOMES AND MEASURES

The primary outcomes were RVGE, severe RVGE, and RVGE hospitalization. Safety-associated outcomes involved serious adverse events, intussusception, and mortality.

RESULTS

A meta-analysis of 20 RCTs and 38 case-control studies revealed that Rotarix (RV1) significantly reduced RVGE (RR, 0.316 [95% CI, 0.224-0.345]) and RVGE hospitalization risk (OR, 0.347 [95% CI, 0.279-0.432]) among children fully vaccinated; RotaTeq (RV5) had similar outcomes (RVGE: RR, 0.350 [95% CI, 0.275-0.445]; RVGE hospitalization risk: OR, 0.272 [95% CI, 0.197-0.376]). Rotavirus vaccines also demonstrated higher protection against severe RVGE. Additionally, no significant differences in the protection of RV1 and RV5 against rotavirus disease were noted in adjusted indirect comparisons. Moderate associations were found between reduced RVGE risk and Rotavac (RR, 0.664 [95% CI, 0.548-0.804]), Rotasiil (RR, 0.705 [95% CI, 0.605-0.821]), and Lanzhou lamb rotavirus vaccine (RR, 0.407 [95% CI, 0.332-0.499]). All rotavirus vaccines demonstrated no risk of serious adverse events. A positive correlation was also found between immunogenicity and vaccine protection (eg, association of RVGE with RV1: coefficient, -1.599; adjusted R2, 99.7%).

CONCLUSIONS AND RELEVANCE

The high protection and low risk of serious adverse events for rotavirus vaccines in children who were fully vaccinated emphasized the importance of worldwide introduction of rotavirus vaccination. Similar protection provided by Rotarix and RotaTeq relieves the pressure of vaccines selection for health care authorities.

Update on rotavirus vaccine underperformance in low- to middle-income countries and next-generation vaccines

In the decade since oral rotavirus vaccines (ORV) were recommended by the World Health Organization for universal inclusion in all national immunization programs, significant yet incomplete progress has been made toward reducing the burden of rotavirus in low- to middle-income countries (LMIC). ORVs continue to demonstrate effectiveness and impact in LMIC, yet numerous factors hinder optimal performance and evaluation of these vaccines. This review will provide an update on ORV performance in LMIC, the increasing body of literature regarding factors that affect ORV response, and the status of newer and next-generation rotavirus vaccines as of early 2020. Fully closing the gap in rotavirus prevention between LMIC and high-income countries will likely require a multifaceted approach accounting for biological and methodological challenges and evaluation and roll-out of newer and next-generation vaccines.

Effectiveness of Rotarix ® vaccine in Africa in the first decade of progressive introduction, 2009-2019: systematic review and meta-analysis

Background: Randomized controlled trials of licensed oral rotavirus group A (RVA) vaccines, indicated lower efficacy in developing countries compared to developed countries. We investigated the pooled effectiveness of Rotarix ^® in Africa in 2019, a decade since progressive introduction began in 2009.

Methods: A systematic search was conducted in PubMed to identify studies that investigated the effectiveness of routine RVA vaccination in an African country between 2009 and 2019. A meta-analysis was undertaken to estimate pooled effectiveness of the full-dose versus partial-dose of Rotarix ^® (RV1) vaccine and in different age groups. Pooled odds ratios were estimated using random effects model and the risk of bias assessed using Newcastle-Ottawa scale. The quality of the evidence was assessed using GRADE.

Results: By December 2019, 39 (72%) countries in Africa had introduced RVA vaccination, of which 34 were using RV1. Thirteen eligible studies from eight countries were included in meta-analysis for vaccine effectiveness (VE) of RVA by vaccine dosage (full or partial) and age categories. Pooled RV1 VE against RVA associated hospitalizations was 44% (95% confidence interval (CI) 28-57%) for partial dose versus 58% (95% CI 50-65%) for full dose. VE was 61% (95% CI 50-69%), 55% (95% CI 32-71%), 56% (95% CI 43-67%), and 61% (95% CI 42-73%) for children aged <12 months, 12-23 months, <24 months and 12-59 months, respectively.

Conclusion: RV1 vaccine use has resulted in a significant reduction in severe diarrhoea in African children and its VE is close to the efficacy findings observed in clinical trials. RV1 VE point estimate was higher for children who received full dose than those who received partial dose, and its protection lasted beyond the first year of life.

Cost estimates of diarrhea hospitalizations among children <5 years old in Zimbabwe

INTRODUCTION

Diarrhoea is a leading killer of children <5 years old, accounting for 480,000 deaths in 2017. Zimbabwe introduced Rotarix into its vaccination program in 2014. In this evaluation, we estimate direct medical, direct non-medical, and indirect costs attributable to a diarrhea hospitalization in Zimbabwe after rotavirus vaccine introduction.

METHODS

Children <5 years old admitted to Harare Central Hospital from June 2018 to April 2019 with acute watery diarrhea were eligible for this evaluation. A 3-part structured questionnaire was used to collect data by interview from the child's family and by review of the medical record. A stool specimen was also collected and tested for rotavirus. Direct medical costs were the sum of medications, consumables, diagnostic tests, and service delivery costs. Direct non-medical costs were the sum of transportation, meals and lodging for caregivers. Indirect costs are the lost income for household members.

RESULTS

A total of 202 children were enrolled with a median age of 12 months (IQR: 7-21) and 48 (24%) had malnutrition. Children were sick for a median of 2 days and most had received outpatient medical care prior to admission. The median monthly household income was higher for well-nourished children compared to malnourished children (p < 0.001). The median total cost of a diarrhea illness resulting in hospitalization was $293.74 (IQR: 188.42, 427.89). Direct medical costs, with a median of $251.74 (IQR: 155.42, 390.96), comprised the majority of the total cost. Among children who tested positive for rotavirus, the median total illness cost was $243.78 (IQR: 160.92, 323.84). The median direct medical costs were higher for malnourished than well-nourished children (p < 0.001).

CONCLUSION

Direct medical costs are the primary determinant of diarrhea illness costs in Zimbabwe. The descriptive findings from this evaluation are an important first step in calculating the cost effectiveness of rotavirus vaccine.

Real-world effectiveness of rotavirus vaccines, 2006-19: a literature review and meta-analysis

BACKGROUND

Since licensure in 2006, rotavirus vaccines have been introduced in more than 100 countries. The efficacy of rotavirus vaccines is variable in settings with different child mortality levels. We did an updated review of the published literature to assess the real-world effectiveness of rotavirus vaccines in a range of settings.

METHODS

In this literature review and meta-analysis, we included observational, post-licensure studies of rotavirus vaccines, published from Jan 1, 2006, to Dec 31, 2019, in English, with laboratory-confirmed rotavirus as the endpoint. In addition to product-specific results for Rotarix (GlaxoSmithKline Biologicals, Rixensart, Belgium) or RotaTeq (Merck, West Point, PA, USA), we included Rotarix and RotaTeq mixed series, and non-product-specific vaccine effectiveness estimates from countries where Rotarix and RotaTeq are both available. Studies of other infant rotavirus vaccines were excluded because little or no post-licensure data were available. We fitted random-effects regression models to estimate vaccine effectiveness among children younger than 12 months and aged 12-23 months. On the basis of 2017 UNICEF mortality estimates for children younger than 5 years, countries were stratified as having low (lowest quartile), medium (second quartile), or high mortality (third and fourth quartiles).

FINDINGS

We identified and screened 1703 articles, of which 60 studies from 32 countries were included. 31 studies were from countries with low child mortality, eight were from medium-mortality countries, and 21 were from high-mortality countries. Rotarix vaccine effectiveness against laboratory-confirmed rotavirus among children younger than 12 months old was 86% (95% CI 81-90) in low-mortality countries, 77% (66-85) in medium-mortality countries, and 63% (54-70) in high-mortality countries. Rotarix vaccine effectiveness among children aged 12-23 months was 86% (81-90) in low-mortality countries, 54% (23-73) in medium-mortality countries, and 58% (38-72) in high-mortality countries. RotaTeq vaccine effectiveness among children younger than 12 months was 86% (76-92) in low-mortality countries and 66% (51-76) in high-mortality countries. RotaTeq vaccine effectiveness among children aged 12-23 months was 84% (79-89) in low-mortality countries. There was no substantial heterogeneity (I² range: 0-36%). Median vaccine effectiveness in low-mortality countries was similar for Rotarix (83%; IQR 78-91), RotaTeq (85%; 81-92), mixed series (86%; 70-91), and non-product-specific (89%; 75-91) vaccination.

INTERPRETATION

Rotavirus vaccines were effective in preventing rotavirus diarrhoea, with higher performance in countries with lower child mortality.

FUNDING

None.

Otieno G, Maia M, N. Agoti C. Effectiveness of Rotarix® vaccine in Africa in the first decade of progressive introduction, 2009-2019: systematic review and meta-analysis

Background: Randomized controlled trials of licensed oral rotavirus group A (RVA) vaccines, indicated lower efficacy in developing countries compared to developed countries. We investigated the pooled effectiveness of Rotarix® in Africa in 2019, a decade since progressive introduction began in 2009. Methods: A systematic search was conducted in PubMed to identify studies that investigated the effectiveness of routine RVA vaccination in an African country between 2009 and 2019. A meta-analysis was undertaken to estimate pooled effectiveness of the full-dose versus partial-dose of Rotarix® (RV1) vaccine and in different age groups. Pooled odds ratios were estimated using random effects model and the risk of bias assessed using Newcastle-Ottawa scale. The quality of the evidence was assessed using GRADE. Results: By December 2019, 39 (72%) countries in Africa had introduced RVA vaccination, of which 34 were using RV1. Thirteen eligible studies from eight countries were included in meta-analysis for vaccine effectiveness (VE) of RVA by vaccine dosage (full or partial) and age categories. Pooled RV1 VE against RVA associated hospitalizations was 44% (95% confidence interval (CI) 28-57%) for partial dose versus 58% (95% CI 50-65%) for full dose. VE was 61% (95% CI 50-69%), 55% (95% CI 32-71%), 56% (95% CI 43-67%), and 61% (95% CI 42-73%) for children aged <12 months, 12-23 months, <24 months and 12-59 months, respectively. Conclusion: RV1 vaccine use has resulted in a significant reduction in severe diarrhoea in African children and its VE is close to the efficacy findings observed in clinical trials. RV1 VE point estimate was higher for children who received full dose than those who received partial dose, and its protection lasted beyond the first year of life.

Overview of the Development, Impacts, and Challenges of Live-Attenuated Oral Rotavirus Vaccines

Safety, efficacy, and cost-effectiveness are paramount to vaccine development. Following the isolation of rotavirus particles in 1969 and its evidence as an aetiology of severe dehydrating diarrhoea in infants and young children worldwide, the quest to find not only an acceptable and reliable but cost-effective vaccine has continued until now. Four live-attenuated oral rotavirus vaccines (LAORoVs) (Rotarix^®, RotaTeq^®, Rotavac^®, and RotaSIIL^®) have been developed and licensed to be used against all forms of rotavirus-associated infection. The efficacy of these vaccines is more obvious in the high-income countries (HIC) compared with the low- to middle-income countries (LMICs); however, the impact is far exceeding in the low-income countries (LICs). Despite the rotavirus vaccine efficacy and effectiveness, more than 90 countries (mostly Asia, America, and Europe) are yet to implement any of these vaccines. Implementation of these vaccines has continued to suffer a setback in these countries due to the vaccine cost, policy, discharging of strategic preventive measures, and infrastructures. This review reappraises the impacts and effectiveness of the current live-attenuated oral rotavirus vaccines from many representative countries of the globe. It examines the problems associated with the low efficacy of these vaccines and the way forward. Lastly, forefront efforts put forward to develop initial procedures for oral rotavirus vaccines were examined and re-connected to today vaccines.