Available evidence on the co-administration of the four-component meningococcal B vaccine (4CMenB) with three vaccines at the same visit among pediatric individuals.

Vaccine co-administration is a useful strategy for improving vaccine coverage and adherence. In Italy, an update to the national immunization program (NIP) in 2023 included recommendations for co-administration of pediatric vaccines, including the four-component vaccine for meningococcus B (4CMenB), pneumococcal conjugate vaccine (PCV), hexavalent vaccines, and oral rotavirus vaccines. Safety is a major concern when considering vaccine co-administration; therefore, a literature review of the available evidence on 4CMenB co-administration with PCV, hexavalent/pentavalent, and rotavirus vaccines was performed. Of 763 publications screened, two studies were reviewed that reported safety data on 4CMenB co-administration with PCV, hexavalent/pentavalent, and rotavirus vaccines in infants aged 0-24 months. Overall, these studies supported that there were no significant safety signals when co-administering 4CMenB with PCV, hexavalent/pentavalent, and rotavirus vaccines, compared with individual vaccination. This review provides key insights for healthcare professionals on the tolerability of co-administering 4CMenB with routine vaccines.

Supporting evidence-based rotavirus vaccine introduction decision-making and implementation: Lessons from 8 Gavi-eligible countries.

Despite the 2009 World Health Organization recommendation that all countries introduce rotavirus vaccines (RVV) into their national immunization programs, just 81 countries had introduced RVV by the end of 2015, leaving millions of children at risk for rotavirus morbidity and mortality. In response, the Rotavirus Accelerated Vaccine Introduction Network (RAVIN) was established in 2016 to provide support to eight Gavi-eligible countries that had yet to make an RVV introduction decision and/or had requested technical assistance with RVV preparations: Afghanistan, Bangladesh, Benin, Cambodia, Democratic Republic of Congo, Lao People's Democratic Republic, Myanmar, and Nepal. During 2016-2020, RAVIN worked with country governments and partners to support evidence-based immunization decision-making, RVV introduction preparation and implementation, and multilateral coordination. By the September 2020 program close-out, five of the eight RAVIN focus countries successfully introduced RVV into their routine childhood immunization programs. We report on the RAVIN approach, describe how the project responded collectively to an evolving RVV product landscape, synthesize common characteristics of the RAVIN country experiences, highlight key lessons learned, and outline the unfinished agenda to inform future new vaccine introduction efforts by countries and global partners.

Molecular epidemiology of rotavirus among children in Western Canada: Dynamic changes in genotype prevalence in four consecutive seasons.

Rotavirus molecular surveillance remains important in the postvaccine era to monitor the changes in transmission patterns, identify vaccine-induced antigenic changes and discover potentially pathogenic vaccine-related strains. The Canadian province of Alberta introduced rotavirus vaccination into its provincial vaccination schedule in June 2015. To evaluate the impact of this program on stool rotavirus positivity rate, strain diversity, and seasonal trends, we analyzed a prospective cohort of children with acute gastroenteritis recruited between December 2014 and August 2018. We identified dynamic changes in rotavirus positivity and genotype trends during pre- and post-rotavirus vaccine introduction periods. Genotypes G9P[8], G1P[8], G2P[4], and G12P[8] predominated consecutively each season with overall lower rotavirus incidence rates in 2016 and 2017. The demographic and clinical features of rotavirus gastroenteritis were comparable among wild-type rotaviruses; however, children with G12P[8] infections were older (p < 0.001). Continued efforts to monitor changes in the molecular epidemiology of rotavirus using whole genome sequence characterization are needed to further understand the impact of the selection pressure of vaccination on rotavirus evolution.

Investigating association between inflammatory bowel disease and rotavirus vaccination in a paediatric cohort in the UK.

In the UK, the incidence and prevalence of inflammatory bowel disease (IBD) is increasing in paediatric populations. Environmental factors including acute gastroenteritis episodes (AGE) may impact IBD development. Infant rotavirus vaccination has been shown to significantly reduce AGE. This study aims to explore the association between vaccination with live oral rotavirus vaccines and IBD development. A population-based cohort study was used, analysing primary care data from the Clinical Practice Research Datalink Aurum. Participants included children born in the UK from 2010 to 2015, followed from a minimum of 6 months old to a maximum of 7 years old. The primary outcome was IBD, and the primary exposure was rotavirus vaccination. Cox regression analysis with random intercepts for general practices was undertaken, with adjustment for potential confounding factors. In a cohort of 907,477 children, IBD was recorded for 96 participants with an incidence rate of 2.1 per 100,000 person-years at risk. The univariable analysis hazard ratio (HR) for rotavirus vaccination was 1.45 (95% confidence interval (CI) 0.93-2.28). Adjustment in the multivariable model attenuated the HR to 1.19 (95% CI 0.53-2.69). This study shows no statistically significant association between rotavirus vaccination and development of IBD. However, it provides further evidence for the safety of live rotavirus vaccination.

Immunogenicity and Safety of a Hexavalent DTwP-IPV-HB-PRP~T Vaccine Versus Separate DTwP-HB-PRP~T, bOPV, and IPV Vaccines Administered at 2, 4, 6 Months of Age Concomitantly With Rotavirus and Pneumococcal Conjugate Vaccines in Healthy Infants in Thailand.

BACKGROUND: This study investigated the immunogenicity and safety of a fully liquid, hexavalent, diphtheria (D)-tetanus (T)-whole-cell pertussis (wP)-inactivated poliovirus (IPV)-hepatitis B (HB)- Haemophilus influenzae b (PRP-T) vaccine compared to licensed DTwP-HB-PRP~T, IPV, and bivalent oral poliovirus (bOPV) vaccines following co-administration with other pediatric vaccines [pneumococcal conjugate vaccine (PCV13) and rotavirus vaccine]. METHODS: Phase III, randomized, open-label study in Thailand. Healthy infants received DTwP-IPV-HB-PRP~T at 2, 4 and 6 months of age (N = 228), or DTwP-HB-PRP~T and bOPV (2, 4 and 6 months of age) and IPV (4 months of age) (N = 231). All participants received PCV13 (2, 4 and 6 months of age) and rotavirus vaccine (2 and 4 months of age). Immunogenicity for all antigens was assessed using validated assays, and noninferiority post-third dose was evaluated for anti-D, anti-T, anti-pertussis [anti-pertussis toxin (anti-PT) and anti-fimbriae 2/3 (anti-FIM)], anti-polio 1, 2, 3, anti-HB, and anti-PRP~T. Safety was assessed using parental reports. RESULTS: Noninferiority was demonstrated for each antigen, and overall noninferiority of DTwP-IPV-HB-PRP~T versus DTwP-HB-PRP~T+bOPV+IPV was concluded. Similarity in each group was observed for the GMC ratio for antirotavirus antibodies (20.9 and 17.3, respectively) and anti-PCV13 antibodies (range: 8.46-32.6 and 7.53-33.1, respectively). Two serious adverse events were related to DTwP-IPV-HB-PRP~T (febrile convulsion and acute febrile illness) and 1 was related to DTwP-HB-PRP~T+bOPV+IPV (febrile seizure), but overall there were no safety concerns with similar rates of participants experiencing solicited (99.1% and 98.3%) and unsolicited (19.3% and 19.5%) adverse events in each group. CONCLUSIONS: This study confirmed the suitability of DTwP-IPV-HB-PRP~T primary series vaccination in combination with rotavirus and PCV13 vaccines.

Impact of maternal antibodies and microbiota development on the immunogenicity of oral rotavirus vaccine in African, Indian, and European infants.

Identifying risk factors for impaired oral rotavirus vaccine (ORV) efficacy in low-income countries may lead to improvements in vaccine design and delivery. In this prospective cohort study, we measure maternal rotavirus antibodies, environmental enteric dysfunction (EED), and bacterial gut microbiota development among infants receiving two doses of Rotarix in India (n = 307), Malawi (n = 119), and the UK (n = 60), using standardised methods across cohorts. We observe ORV shedding and seroconversion rates to be significantly lower in Malawi and India than the UK. Maternal rotavirus-specific antibodies in serum and breastmilk are negatively correlated with ORV response in India and Malawi, mediated partly by a reduction in ORV shedding. In the UK, ORV shedding is not inhibited despite comparable maternal antibody levels to the other cohorts. In both India and Malawi, increased microbiota diversity is negatively correlated with ORV immunogenicity, suggesting that high early-life microbial exposure may contribute to impaired vaccine efficacy.

Do Rotavirus Strains Affect Vaccine Effectiveness? A Systematic Review and Meta-analysis.

BACKGROUND: Rotavirus causes 215,000 deaths from severe childhood diarrhea annually. Concerns exist that a monovalent vaccine (RV1) and a pentavalent vaccine (RV5) may be less effective against rotavirus strains not contained in the vaccines. We estimated the vaccine effectiveness (VE) of RV1 and RV5 against severe rotavirus gastroenteritis caused by vaccine (homotypic) and nonvaccine (partially and fully heterotypic) strains. METHODS: After conducting a systematic review, we meta-analyzed 31 case-control studies (N = 27,293) conducted between 2006 and 2020 using a random-effects regression model. RESULTS: In high-income countries, RV1 VE was 10% lower against partially heterotypic (P = 0.04) and fully heterotypic (P = 0.10) compared with homotypic strains (homotypic VE: 90% [95% confidence intervals (CI): 82-94]; partially heterotypic VE: 79% [95% CI: 71-85]; fully heterotypic VE: 80% [95% CI: 65-88]). In middle-income countries, RV1 VE was 14-16% lower against partially heterotypic (P = 0.06) and fully heterotypic (P = 0.04) compared with homotypic strains (homotypic VE: 81% [95% CI: 69-88]; partially heterotypic VE: 67% [95% CI: 54-76]; fully heterotypic VE: 65% [95% CI: 51-75]). Strain-specific RV5 VE differences were less pronounced, and primarily derived from high-income countries. Limited data were available from low-income countries. CONCLUSIONS: Vaccine effectiveness of RV1 and RV5 was somewhat lower against nonvaccine than vaccine strains. Ongoing surveillance is important to continue long-term monitoring for strain replacement, particularly in low-income settings where data are limited.

Reduction in Severity of All-Cause Gastroenteritis Requiring Hospitalisation in Children Vaccinated against Rotavirus in Malawi.

Rotavirus is the major cause of severe gastroenteritis in children aged <5 years. Introduction of the G1P[8] Rotarix® rotavirus vaccine in Malawi in 2012 has reduced rotavirus-associated hospitalisations and diarrhoeal mortality. However, the impact of rotavirus vaccine on the severity of gastroenteritis presented in children requiring hospitalisation remains unknown. We conducted a hospital-based surveillance study to assess the impact of Rotarix® vaccination on the severity of gastroenteritis presented by Malawian children. Stool samples were collected from children aged <5 years who required hospitalisation with acute gastroenteritis from December 2011 to October 2019. Gastroenteritis severity was determined using Ruuska and Vesikari scores. Rotavirus was detected using enzyme immunoassay. Rotavirus genotypes were determined using nested RT-PCR. Associations between Rotarix® vaccination and gastroenteritis severity were investigated using adjusted linear regression. In total, 3159 children were enrolled. After adjusting for mid-upper arm circumference (MUAC), age, gender and receipt of other vaccines, all-cause gastroenteritis severity scores were 2.21 units lower (p < 0.001) among Rotarix®-vaccinated (n = 2224) compared to Rotarix®-unvaccinated children (n = 935). The reduction in severity score was observed against every rotavirus genotype, although the magnitude was smaller among those infected with G12P[6] compared to the remaining genotypes (p = 0.011). Each one-year increment in age was associated with a decrease of 0.43 severity score (p < 0.001). Our findings provide additional evidence on the impact of Rotarix® in Malawi, lending further support to Malawi's Rotarix® programme.

Rotavirus Vaccine Safety and Effectiveness in Infants With High-Risk Medical Conditions.

OBJECTIVES: Rotavirus vaccination has 87% to 100% effectiveness against severe rotavirus acute gastroenteritis (AGE) in healthy infants in high-income countries. Little is known whether infants with medical risk conditions (MRCs) are equally protected and if the vaccine is equally well tolerated. We conducted a quasi-experimental prospective multicenter before-after cohort study to assess the vaccine effectiveness (VE) and safety profile of the human rotavirus vaccine (HRV) among MRC infants that required prolonged or frequent postnatal care. METHODS: The Netherlands has no national rotavirus immunization program, but HRV was implemented in routine care for MRC infants in 13 Dutch hospitals. Participants in the before and after cohort, HRV unvaccinated and vaccinated, respectively, were followed for occurrence of (rotavirus) AGE. VE of at least 1 dose was estimated by using time-to-event analysis for severe rotavirus AGE. Vaccine-related serious adverse event (AEs) after HRV were retrieved systematically from medical charts. Solicited AEs after vaccinations were prospectively collected and compared between vaccination time points with or without HRV. RESULTS: In total, 1482 high-risk infants with MRC were enrolled, including 631 in the before and 851 in the after cohorts; 1302 infants were premature (88.3%), 447 were small for gestational age (30.2%), and 251 had at least 1 congenital disorder (17.0%). VE against severe rotavirus AGE was 30% (95% confidence interval [CI]: -36% to 65%). Overall, the observed number of rotavirus hospitalizations was low and not significantly different between the cohorts (2 and 2, respectively). The rate of vaccine-related serious AE was 0.24 per 100 vaccine doses. The adjusted risk ratio for any AE after HRV vaccination compared with other routine vaccinations was 1.09 (95% CI: 1.05 to 1.12) for concomitant administration and 0.91 (95% CI: 0.81 to 0.99) for single HRV administration. Gastrointestinal AEs were 10% more frequent after HRV. CONCLUSIONS: In contrast to previous findings among healthy term infants, in routine use, HRV offered limited protection to vulnerable medical risk infants. HRV is generally well tolerated in this group in single administration, but when coadministered with routine vaccines, it is associated with higher risk of (mostly gastrointestinal) AE. Our study highlights the importance of studying vaccine performance in subgroups of medically vulnerable infants.

The Rotavirus Vaccine Story: From Discovery to the Eventual Control of Rotavirus Disease.

Worldwide, rotavirus is the leading pathogen causing severe diarrhea in children and a major cause of under 5 years mortality. In 1998, the first rotavirus vaccine, RotaShield, was licensed in the United States but a rare adverse event, intussusception, led to its withdrawal. Seven years passed before the next generation of vaccines became available, Rotarix (GSK) and Rotateq (Merck), and 11 years later, 2 additional vaccines from India, Rotavac (Bharat) and Rotasiil (Serum Institute), were recommended by World Health Organization for all children. Today, these vaccines are used in more than 100 countries and have contributed to marked decreases in hospitalizations and deaths from diarrhea. However, these live oral vaccines are less effective in low-income countries with high under 5 years mortality for reasons that are not understood. Efforts to develop new vaccines that avoid the oral route are in progress and will likely be needed to ultimately control rotavirus disease.

Global Rotavirus and Pneumococcal Conjugate Vaccine Introductions and the Association With Country Disease Surveillance, 2006-2018.

BACKGROUND: To inform the introduction of pneumococcal conjugate vaccine (PCV) and rotavirus vaccine, the World Health Organization (WHO) established the Global Invasive Bacterial Vaccine-Preventable Disease Surveillance Network (GISN) and the Global Rotavirus Surveillance Network (GRSN) in 2008. We investigated whether participation in these networks or other surveillance was associated with vaccine introduction. METHODS: Between 2006 and 2018, among all WHO member states, we used multivariable models adjusting for economic status to assess (1) the association between surveillance for pneumococcal disease or rotavirus disease, including participation in GISN or GRSN and the introduction of the PCV or the rotavirus vaccine, respectively, and (2) the association between the rotavirus disease burden and the rotavirus vaccine introduction among 56 countries participating in GRSN from 2008 to 2018. RESULTS: Countries that participated in or conducted surveillance for invasive pneumococcal disease or rotavirus disease were 3.5 (95% confidence interval [CI], 1.7-7.1) and 4.2 (95% CI, 2.1-8.6) times more likely to introduce PCV or rotavirus respectively, compared to those without surveillance. Among countries participating in GRSN, there was insufficient evidence to demonstrate an association between countries with higher rotavirus positivity and vaccine introduction. CONCLUSIONS: Surveillance should be incorporated into advocacy strategies to encourage the introduction of vaccines, with countries benefiting from data from, support for, and coordination of international disease surveillance networks.

Intussusception among infants in Tanzania: findings from prospective hospital-based surveillance, 2013-2016.

INTRODUCTION: intussusception surveillance was initiated in Tanzania in 2013 after monovalent rotavirus vaccine was introduced, as part of the 7-country African evaluation to assess whether the vaccine was associated with an increased risk of intussusception. An increased risk from vaccine was not identified. Published data on intussusception in Tanzanian infants are limited. METHODS: prospective intussusception surveillance was conducted at 7 referral hospitals during 2013-2016 to identify all infants with intussusception meeting Brighton Level 1 criteria. Demographic, household and clinical data were collected by hospital clinicians and analyzed. RESULTS: a total of 207 intussusception cases were identified. The median age of cases was 5.8 months and nearly three-quarters were aged 4-7 months. Median number of days from symptom onset to admission at treatment hospital was 3 (IQR 2-5). Seventy-eight percent (152/195) of cases had been admitted at another hospital before transfer to the treating hospital. Enema reduction was not available; all infants were treated surgically and 55% (114/207) had intestinal resection. The overall case-fatality rate was 30% (62/206). Compared with infants who survived, those who died had longer duration of symptoms before admission to treatment hospital (median 4 vs 3 days; p < 0.01), higher rate of intestinal resection (81% [60/82] vs 44% [64/144], p < 0.001), and from families with lower incomes (i.e., less likely to own a television [p < 0.01] and refrigerator [p < 0.05). CONCLUSION: Tanzanian infants who develop intussusception have a high case-fatality rate. Raising the index of suspicion among healthcare providers, allocating resources to allow wider availability of abdominal ultrasound for earlier diagnosis, and training teams in ultrasound-guided enema reduction techniques used in other African countries could reduce the fatality rate.

Age distribution and mortality associated with intussusception in children under two years of age in nine sentinel surveillance hospitals in Zambia, 2007-2018.

INTRODUCTION: recipients of monovalent rotavirus vaccine have a low risk of developing intussusception (IS) in high- to medium-high-income countries. In sub-Saharan Africa, Zambia included, this risk of IS has not been assessed. Two-dose monovalent rotavirus vaccine, introduced in Zambia in 2012 in the capital of Lusaka, and rolled out countrywide in 2013, is administered at 6 and 10 weeks of age with no catch-up dose. Active IS surveillance monitoring in children < 2 years has been ongoing in Zambia since July 2009 and additional retrospective review was conducted from 2007- June 2009. METHODS: retrospective review (January 2007-June 2009) and prospective (July 2009-December 2018) IS surveillance was conducted at nine hospitals and four large paediatric hospital departments in Zambia, respectively. Demographic and clinical data were collected from medical folder abstraction and supplemented by parental interview during prospective surveillance. RESULTS: a total of 248 children < 2 years with IS were identified; 57.3% were male. Most cases with IS were infants (85.5%). IS admissions remained stable during the surveillance period with no seasonality pattern although an increase in cases occurred between August and October, hot dry season. The median time from symptom onset to presentation for treatment was 2 days and 63.6% (154/242) of IS diagnoses were made during surgery. The bowel resection rate was 46.6%. A high CFR of 23.3% was observed. CONCLUSION: the number of intussusception cases in Zambia was relatively small and remained stable over the 12-year study period. However, a high CFR was observed among cases.

Intussusception in children under five years of age in Enugu, Nigeria.

INTRODUCTION: intussusception is the invagination of a segment of the bowel into a distal segment. It occurs predominantly in infants worldwide. Following documentation of increased incidence after introduction of the first rotavirus vaccine (Rotashield, Wyeth-Lederle), it has become a standard recommendation to maintain surveillance for intussusception as newer rotavirus vaccines are introduced into EPI. Nigeria plans to introduce rotavirus vaccine in 2020. Pre-vaccine introduction surveillance will serve as a baseline to understand the epidemiology of intussusception in Nigeria. METHODS: from 2013 to 2017, prospective enrolment of under five children with intussusception was done following the WHO protocol and using the WHO case report form. Only children who met the Pan American Health Organization/World Health Organization (PAHO/WHO) protocol case definition for intussusception were enrolled. These children were monitored until discharge or death. Clinical features and outcome were recorded in the case report form. RESULTS: a total of 63 cases were enrolled, with age range of 3 to 42 months (median: 6 months, IQR: 5-9 months). Majority were within 4-6 months and 96% were < 12 months old. There were 41 males and 22 females (male to female ratio of 1.9:1). Duration of symptoms before presentation ranged from 2 hours to 15 days (median: 72 hours). Fifty-seven patients had abdominal ultrasound and 52 patients (83%) had surgery. Case fatality rate was 9% and duration of hospitalization ranged from 1 to 30 days (median 10 days, IQR 8-15 days). CONCLUSION: intussusception occurred most commonly in infants but well beyond the proposed age for rotavirus vaccination in the population studied. Late presentation and surgical intervention were common. This data provides a good baseline description of the epidemiology of intussusception.

Rotavirus A infection in pre- and post-vaccine period: Risk factors, genotypes distribution by vaccination status and age of children in Nampula Province, Northern Mozambique (2015-2019).

Mozambique introduced the monovalent rotavirus vaccine (Rotarix®, GSK Biologicals, Rixensart, Belgium) in September 2015. Previous analysis, showed that Nampula province continues reporting a high frequency of Rotavirus A (RVA) infection and the emergence of G9P[6], G9P[4] and G3P[4] genotypes. This analysis aimed to determine the RVA frequency; risk factors; genotype distribution by vaccination status and age between pre- and post-vaccine periods in children under-five years old with diarrhea in Nampula. A cross-sectional, hospital-based surveillance study was conducted in the Hospital Central de Nampula in Mozambique. Socio-demographic and clinical data were collected to assess factors related to RVA infection in both periods. Stool specimens were screened to detect RVA by ELISA, and positive samples were genotyped. Between 2015 (pre-vaccine period) and 2016-2019 (post-vaccine period), 614 stool specimens were collected and tested for RVA in which 34.9% (67/192) were positive in pre-vaccine period and 21.8% (92/422) in post-vaccine (p = 0.001). In the post-vaccine period, age, year, and contact with different animal species (chicken, duck, or multiple animals) were associated with RVA infection. RVA infection was higher in children partially vaccinated (40.7%, 11/27) followed by the fully vaccinated (29.3%, 56/191) and the unvaccinated (15.3%, 21/137) (p = 0.002). G1P[8] and G9P[4] were common in vaccinated children less than 12 months. The present analysis showed that RVA infection reduced slightly in the post-vaccine period, with a high proportion of infection and genotype diversity in children, under 12 months of age, vaccinated. Further research on factors associated with RVA infection on vaccinated compared to unvaccinated children and vaccination optimization should be done.

Global Experience With Rotavirus Vaccines.

Rotavirus is a major cause of severe pediatric diarrhea worldwide. In 2006, 2 live, oral rotavirus vaccines, Rotarix and RotaTeq, were licensed for use in infants and were rapidly adopted in many high- and middle-income settings where efficacy had been demonstrated in clinical trials. Following completion of successful trials in low-income settings, the World Health Organization (WHO) recommended rotavirus vaccination for all infants globally in 2009. In 2018, 2 new rotavirus vaccines, Rotasiil and Rotavac, were prequalified by WHO, expanding global availability. As of March 2021, rotavirus vaccines have been introduced nationally in 106 countries. Since, Rotavirus vaccines have demonstrated effectiveness against severe disease and mortality, even among age groups in eligible for vaccination. Cross-genotypic protection has been demonstrated, and the favorable benefit-risk profile of these vaccines continues to be confirmed. Ongoing research seeks to better understand reasons for the geographic disparities in effectiveness observed, in order to optimize vaccine strategies worldwide.

Impact of Monovalent Rotavirus Vaccine on Rotavirus Hospitalizations among Children Younger Than 5 Years of Age in the Ouest and Artibonite Departments, Haiti, 2013 to 2019.

Rotavirus is responsible for 26% of diarrheal deaths in Latin America and the Caribbean. Haiti introduced the monovalent rotavirus vaccine in April 2014. The objective of this analysis is to describe the impact of the rotavirus vaccine on hospitalizations among Haitian children younger than 5 years old during the first 5 years after introduction. This analysis includes all children with diarrhea who were enrolled as part of a sentinel surveillance system at two hospitals from May 2013 to April 2019. We compare the proportion of rotavirus-positive specimens in each post-vaccine introduction year to the pre-vaccine period. To account for the potential dilution of the proportion of rotavirus-positive specimens from a waning cholera outbreak, we also analyzed annual trends in the absolute number of positive stools, fit a two-component finite-mixture model to the negative specimens, and fit a negative binomial time series model to the pre-vaccine rotavirus-positive specimens to predict the number of rotavirus diarrhea hospital admissions in the absence of rotavirus vaccination. The overall percentage of rotavirus-positive specimens declined by 22% the first year after introduction, increased by 17% the second year, and declined by 33% to 50% the subsequent 3 years. All sensitivity analyses confirmed an overall decline. We observed a clear annual rotavirus seasonality before and after vaccine introduction, with the greatest activity in December through April, and a biennial pattern, with high sharp peaks and flatter longer periods of increased rotavirus activity in alternating years, consistent with suboptimal vaccination coverage. Overall, our study shows evidence that the introduction of the rotavirus vaccine reduced the burden of severe rotavirus diarrhea.

Investigating barriers to the protective efficacy provided by rotavirus vaccines in African infants.

Julie Bines discusses an accompanying study by Sheila Isanaka and colleagues on nutrient supplementation and immune responses to rotavirus vaccination.

Immunogenicity of an oral rotavirus vaccine administered with prenatal nutritional support in Niger: A cluster randomized clinical trial.

BACKGROUND: Nutritional status may play a role in infant immune development. To identify potential boosters of immunogenicity in low-income countries where oral vaccine efficacy is low, we tested the effect of prenatal nutritional supplementation on immune response to 3 doses of a live oral rotavirus vaccine. METHODS AND FINDINGS: We nested a cluster randomized trial within a double-blind, placebo-controlled randomized efficacy trial to assess the effect of 3 prenatal nutritional supplements (lipid-based nutrient supplement [LNS], multiple micronutrient supplement [MMS], or iron-folic acid [IFA]) on infant immune response (n = 53 villages and 1,525 infants with valid serology results: 794 in the vaccine group and 731 in the placebo group). From September 2015 to February 2017, participating women received prenatal nutrient supplement during pregnancy. Eligible infants were then randomized to receive 3 doses of an oral rotavirus vaccine or placebo at 6-8 weeks of age (mean age: 6.3 weeks, 50% female). Infant sera (pre-Dose 1 and 28 days post-Dose 3) were analyzed for anti-rotavirus immunoglobulin A (IgA) using enzyme-linked immunosorbent assay (ELISA). The primary immunogenicity end point, seroconversion defined as ≥3-fold increase in IgA, was compared in vaccinated infants among the 3 supplement groups and between vaccine/placebo groups using mixed model analysis of variance procedures. Seroconversion did not differ by supplementation group (41.1% (94/229) with LNS vs. 39.1% (102/261) with multiple micronutrients (MMN) vs. 38.8% (118/304) with IFA, p = 0.91). Overall, 39.6% (n = 314/794) of infants who received vaccine seroconverted, compared to 29.0% (n = 212/731) of infants who received placebo (relative risk [RR]: 1.36; 95% confidence interval [CI]: 1.18, 1.57, p < 0.001). This study was conducted in a high rotavirus transmission setting. Study limitations include the absence of an immune correlate of protection for rotavirus vaccines, with the implications of using serum anti-rotavirus IgA for the assessment of immunogenicity and efficacy in low-income countries unclear. CONCLUSIONS: This study showed no effect of the type of prenatal nutrient supplementation on immune response in this setting. Immune response varied depending on previous exposure to rotavirus, suggesting that alternative delivery modalities and schedules may be considered to improve vaccine performance in high transmission settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT02145000.

Rotavirus vaccine efficacy up to 2 years of age and against diverse circulating rotavirus strains in Niger: Extended follow-up of a randomized controlled trial.

BACKGROUND: Rotavirus vaccination is recommended in all countries to reduce the burden of diarrhea-related morbidity and mortality in children. In resource-limited settings, rotavirus vaccination in the national immunization program has important cost implications, and evidence for protection beyond the first year of life and against the evolving variety of rotavirus strains is important. We assessed the extended and strain-specific vaccine efficacy of a heat-stable, affordable oral rotavirus vaccine (Rotasiil, Serum Institute of India, Pune, India) against severe rotavirus gastroenteritis (SRVGE) among healthy infants in Niger. METHODS AND FINDINGS: From August 2014 to November 2015, infants were randomized in a 1:1 ratio to receive 3 doses of Rotasiil or placebo at approximately 6, 10, and 14 weeks of age. Episodes of gastroenteritis were assessed through active and passive surveillance and graded using the Vesikari score. The primary endpoint was vaccine efficacy of 3 doses of vaccine versus placebo against a first episode of laboratory-confirmed SRVGE (Vesikari score ≥ 11) from 28 days after dose 3, as previously reported. At the time of the primary analysis, median age was 9.8 months. In the present paper, analyses of extended efficacy were undertaken for 3 periods (28 days after dose 3 to 1 year of age, 1 to 2 years of age, and the combined period 28 days after dose 3 to 2 years of age) and by individual rotavirus G type. Among the 3,508 infants included in the per-protocol efficacy analysis (mean age at first dose 6.5 weeks; 49% male), the vaccine provided significant protection against SRVGE through the first year of life (3.96 and 9.98 cases per 100 person-years for vaccine and placebo, respectively; vaccine efficacy 60.3%, 95% CI 43.6% to 72.1%) and over the entire efficacy follow-up period up to 2 years of age (2.13 and 4.69 cases per 100 person-years for vaccine and placebo, respectively; vaccine efficacy 54.7%, 95% CI 38.1% to 66.8%), but the difference was not statistically significant in the second year of life. Up to 2 years of age, rotavirus vaccination prevented 2.56 episodes of SRVGE per 100 child-years. Estimates of efficacy against SRVGE by individual rotavirus genotype were consistent with the overall protective efficacy. Study limitations include limited generalizability to settings with administration of oral polio virus due to low concomitant administration, limited power to assess vaccine efficacy in the second year of life owing to a low number of events among older children, potential bias due to censoring of placebo children at the time of study vaccine receipt, and suboptimal adapted severity scoring based on the Vesikari score, which was designed for use in settings with high parental literacy. CONCLUSIONS: Rotasiil provided protection against SRVGE in infants through an extended follow-up period of approximately 2 years. Protection was significant in the first year of life, when the disease burden and risk of death are highest, and against a changing pattern of rotavirus strains during the 2-year efficacy period. Rotavirus vaccines that are safe, effective, and protective against multiple strains represent the best hope for preventing the severe consequences of rotavirus infection, especially in resource-limited settings, where access to care may be limited. Studies such as this provide valuable information for the planning of national immunization programs and future vaccine development. TRIAL REGISTRATION: ClinicalTrials.gov NCT02145000.