Rotavirus Vaccine Administration in Preterm and Medically Fragile Infants Admitted to Neonatal Intensive Care Units: Second Phase Enrollments and Final Results of a Multicenter Observational Study Conducted in Sicily, Italy

Rotavirus disease is the world's leading cause of severe gastroenteritis and mortality in children up to 5 years of age. Premature infants are more vulnerable to rotavirus gastroenteritis (RVGE) and its complications. International authorities strongly recommend vaccination because of the consistent reduction in infections, hospitalizations, deaths, and related costs.

BACKGROUND/OBJECTIVES

The objective of the present study was to evaluate the safety of anti-rotavirus vaccination in premature infants admitted and vaccinated in the main Sicilian Neonatal Intensive Care Units (NICUs) during the pandemic period.

METHODS

The human monovalent rotavirus vaccination (RV1) was administered to preterm infants of gestational age ≥28 weeks in the main Sicilian NICUs from January 2020 to December 2022, as a prolongation of a similar study conducted from April 2018 to December 2019. Rotavirus vaccinations were provided both to hospitalized infants and to those returning for post-discharge follow-up, beginning at six weeks of age according to the official immunization schedule. All potential adverse events-whether expected, unexpected, or serious-were recorded from the day of vaccination through 14 days (first follow-up) and 28 days (second follow-up) after each of the two scheduled doses.

RESULTS

A total of 355 preterm infants were fully vaccinated with RV in four Sicilian NICUs. The mean gestational age of newborns was 33.2 weeks (±2.7), 53% of whom were male. Vaccination was performed on average at 7 weeks of age (±2.1), and the mean weight at the time of vaccination was 3439 g (SD ± 745.2). No expected/unexpected or serious adverse events were observed either within the 14-day or within the 28-day period after administration of both two doses.

CONCLUSIONS

Data confirm that vaccination in preterm infants ≥28 weeks gestational age is safe. The prolongation of this Public Health strategy, strongly recommended by the Sicilian Health Department during the pandemic period that also generally has led to a reduction of vaccination adherence and acceptance of pediatric vaccination, demonstrates the importance of multidisciplinary collaboration with neonatologists and pediatricians to continue promoting in-hospital vaccinations for fragile subjects.

Impact of Vaccination on Rotavirus Genotype Diversity: A Nearly Two-Decade-Long Epidemiological Study before and after Rotavirus Vaccine Introduction in Sicily, Italy

Sicily was the first Italian region to introduce rotavirus (RV) vaccination with the monovalent G1P[8] vaccine Rotarix® in May 2012. In this study, the seasonal distribution and molecular characterization of RV strains detected over 19 years were compared to understand the effect of Rotarix® on the evolutionary dynamics of human RVs. A total of 7846 stool samples collected from children < 5 years of age, hospitalized with acute gastroenteritis, were tested for RV detection and genotyping. Since 2013, vaccine coverage has progressively increased, while the RV prevalence decreased from 36.1% to 13.3% with a loss of seasonality. The local distribution of RV genotypes changed over the time possibly due to vaccine introduction, with a drastic reduction in G1P[8] strains replaced by common and novel emerging RV strains, such as equine-like G3P[8] in the 2018−2019 season. Comparison of VP7 and VP4 amino acid (aa) sequences with the cognate genes of Rotarix® and RotaTeq® vaccine strains showed specific aa changes in the antigenic epitopes of VP7 and of the VP8* portion of VP4 of the Italian RV strains. Molecular epidemiological surveillance data are required to monitor the emergence of novel RV strains and ascertain if these strains may affect the efficacy of RV vaccines.

Benefit-Risk Assessment of Vaccines. Part I: A Systematic Review to Identify and Describe Studies About Quantitative Benefit-Risk Models Applied to Vaccines

Introduction

Understanding the balance between the benefits and risks of vaccination is essential to ensure informed and adequate public health decision making. Quantitative benefit–risk models (qBRm) represent useful tools to help decision makers with supporting benefit–risk assessment throughout the lifecycle of a medical product. However, few initiatives have been launched to harmonise qBRm approaches, specifically for vaccines.

Objectives

The aim of this paper was to identify publications about qBRm applied to vaccines through a systematic literature review, and to describe their characteristics.

Methods

Medline, Scopus and Institute for Scientific Information Web of Knowledge databases were searched to identify articles in English, published from database inceptions up to December 2019. The search strategy included the combination of three key concepts: ‘benefit–risk’, ‘modelling’ and ‘vaccines’. Data extracted included the modelling context and the methodological approaches used.

Results

Of 3172 publications screened, 48 original publications were included. Most of the selected studies were published over the past decade and focused on rotavirus (15), dengue (10) and influenza (6) vaccines. The majority (30) of studies reported analyses related to high-income countries. The methodology of the studies differed, particularly in modelling techniques, benefit–risk measures, and sensitivity analyses. The present work also pointed out a high level of variability in the quality of reporting across studies, with particular regard to input parameters and methodological approaches.

Conclusions

This review provides an extensive list of qBRm applied to vaccines. Discrepancies across studies were identified during our review. While the number of published qBRm studies is increasing, no reporting guidance for qBRm applied to vaccines is currently available. This may affect decision makers’ confidence in the results and their benefit–risk assessment(s); therefore, the development of such reporting guidance is highly needed.

Electronic supplementary material

The online version of this article (10.1007/s40264-020-00984-7) contains supplementary material, which is available to authorized users.

Evaluating the potential economic and health impact of rotavirus vaccination in 63 middle-income countries not eligible for Gavi funding: a modelling study

BACKGROUND

Middle-income countries (MICs) that are not eligible for funding from Gavi, the Vaccine Alliance, have been slow to adopt rotavirus vaccines. Few studies have evaluated the cost-effectiveness and benefit-risk of rotavirus vaccination in these settings. We aimed to assess the potential economic and health impact of rotavirus vaccination in 63 MICs not eligible for funding from Gavi.

METHODS

In this modelling study, we estimated the cost-effectiveness and benefit-risk of rotavirus vaccination in 63 MICs not eligible to Gavi funding. We used an Excel-based proportionate outcomes model with a finely disaggregated age structure to estimate the number of rotavirus gastroenteritis cases, clinic visits, hospitalisations, and deaths averted by vaccination in children younger than 5 years over a 10-year period. We calculated cost-effectiveness ratios (costs per disability-adjusted life-years averted compared with no vaccination) and benefit-risk ratios (number of hospitalisations due to rotavirus gastroenteritis averted per excess hospitalisations due to intussusception). We evaluated three alternative vaccines available globally (Rotarix, Rotavac, and Rotasiil) and used information from vaccine manufacturers regarding anticipated vaccine prices. We ran deterministic and probabilistic uncertainty analyses.

FINDINGS

Over the period 2020-29, rotavirus vaccines could avert 77 million (95% uncertainty interval [UI] 51-103) cases of rotavirus gastroenteritis and 21 million (12-36) clinic visits, 3 million (1·4-5·6) hospitalisations, and 37 900 (25 900-55 900) deaths due to rotavirus gastroenteritis in 63 MICs not eligible for Gavi support. From a government perspective, rotavirus vaccination would be cost-effective in 48 (77%) of 62 MICs considered. The benefit-risk ratio for hospitalisations prevented versus those potentially caused by vaccination exceeded 250:1 in all countries.

INTERPRETATION

In most MICs not eligible for Gavi funding, rotavirus vaccination has high probability to be cost-effective with a favourable benefit-risk profile. Policy makers should consider this new evidence when making or revisiting decisions on the use of rotavirus vaccines in their respective countries.

FUNDING

Bill & Melinda Gates Foundation.

Intussusception in 2 Children With Severe Acute Respiratory Syndrome Coronavirus-2 Infection

We note that intussusception was likely associated with severe acute respiratory syndrome coronavirus-2 infection in 2 infants in Wuhan and London. The intussusception was reduced by enemas in Wuhan; the outcome was fatal. The intussusception was not reduced by enemas in London and required surgery; the outcome was favorable.

Rotavirus A in Brazil: Molecular Epidemiology and Surveillance during 2018-2019

Rotavirus A (RVA) vaccines succeeded in lowering the burden of acute gastroenteritis (AGE) worldwide, especially preventing severe disease and mortality. In 2019, Brazil completed 13 years of RVA vaccine implementation (Rotarix™) within the National Immunization Program (NIP), and as reported elsewhere, the use of Rotarix™ in the country has reduced childhood mortality and morbidity due to AGE. Even though both marketed vaccines are widely distributed, the surveillance of RVA causing AGE and the monitoring of circulating genotypes are important tools to keep tracking the epidemiological scenario and vaccines impact. Thus, our study investigated RVA epidemiological features, viral load and G and P genotypes circulation in children and adults presenting AGE symptoms in eleven states from three out of five regions in Brazil. By using TaqMan^®-based one-step RT-qPCR, we investigated a total of 1536 stool samples collected from symptomatic inpatients, emergency department visits and outpatients from January 2018 to December 2019. G and P genotypes of RVA-positive samples were genetically characterized by multiplex RT-PCR or by nearly complete fragment sequencing. We detected RVA in 12% of samples, 10.5% in 2018 and 13.7% in 2019. A marked winter/spring seasonality was observed, especially in Southern Brazil. The most affected age group was children aged >24-60 months, with a positivity rate of 18.8% (p < 0.05). Evaluating shedding, we found a statistically lower RVA viral load in stool samples collected from children aged up to six months compared to the other age groups (p < 0.05). The genotype G3P[8] was the most prevalent during the two years (83.7% in 2018 and 65.5% in 2019), and nucleotide sequencing of some strains demonstrated that they belonged to the emergent equine-like G3P[8] genotype. The dominance of an emergent genotype causing AGE reinforces the need for continuous epidemiological surveillance to assess the impact of mass RVA immunization as well as to monitor the emergence of novel genotypes.

Quantitative Benefit-Risk Models Used for Rotavirus Vaccination: A Systematic Review

Background

Although rotavirus vaccines have proven to prevent the risk of rotavirus gastroenteritis (RVGE) in children under 5 years old, they are also associated with an increased transient risk of intussusception (IS). Several quantitative benefit-risk models (qBRm) are performed to measure this balance in hospitalizations and deaths prevented versus the ones induced.

Method

In this study, our objective was to provide a complete overview of qBRm used for rotavirus vaccination. We systematically searched 3 medical literature databases to identify relevant articles, in English, that were published between 2006 and 2019.

Results

Of the 276 publications screened, 14 studies using qBRm for rotavirus vaccination were retained, based on preselected criteria. Four were performed in low- and middle-income countries. Almost all (13 of 14) displayed the following characteristics: force of infection assumed to be constant over time (static model), indirect effect of rotavirus vaccination (herd effect) not considered, closed model (individuals not allowed to enter and/or exit the model over time), and aggregated level (no tracking of individual's behavior). Most of the models were probabilistic (9 of 14) and reported sensitivity and/or scenario analyses (12 of 14). Input parameter values varied across studies. Selected studies suggest that, depending on the models used, for every IS hospitalization and death induced, vaccination would prevent, respectively, 190-1624 and 71-743 RVGE-related hospitalizations and deaths.

Conclusions

The benefits of rotavirus vaccination were shown to largely exceed the increased risk of IS, across all studies. Future research aiming to harmonize qBRm for rotavirus vaccination should ensure the comparability of studies and provide additional information for regulatory authorities, physicians, and patients.

Benefit Versus Risk Assessment of Rotavirus Vaccination in France: A Simulation and Modeling Analysis

Introduction

Two vaccines against rotavirus gastroenteritis (RVGE) in young children, Rotarix and RotaTeq, have been available in Europe since 2006. Vaccination against rotaviruses significantly reduces the burden of RVGE, but it is also associated with a very small increased risk of intussusception. In a benefit–risk analysis, the prevented RVGE burden is weighed against the possible excess of intussusception.

Purpose

The aim was to compare the estimated benefits and risks of Rotarix vaccination in France.

Methods

We estimated the benefits (vaccine-preventable RVGE hospitalizations and deaths) and risks (vaccine-caused intussusception hospitalizations and deaths) following two doses of Rotarix in a birth cohort of 791,183 followed for 3–5 years in France. We used data from peer-reviewed clinical and epidemiological studies or publications, and government statistics.

Results

Within the total number of French children below 5 years of age, we estimate vaccination could prevent a median 11,132 [95% credible interval (CI) 7842–14,408] RVGE hospitalizations and 7.43 (95% CI 3.27–14.68) RVGE deaths. At the same time, vaccination could cause an average of 6.86 (95% CI 2.25–38.37) intussusception hospitalizations and 0.0099 (95% CI 0.0024–0.060) intussusception deaths in the entire French birth cohort of infants below 1 year of age. Therefore, for every intussusception hospitalization and every intussusception death caused by vaccination, 1624 (95% CI 240–5243) RVGE hospitalizations and 743 (95% CI 93–3723) RVGE deaths are prevented, respectively, by vaccination.

Conclusions

The vaccine-prevented RVGE hospitalizations and deaths (benefit) greatly outweigh the excess potentially vaccination-related cases of intussusception (risk), indicating a favorable benefit–risk balance for Rotarix in France.

Electronic supplementary material

The online version of this article (10.1007/s40259-018-0273-6) contains supplementary material, which is available to authorized users.

A benefit-risk analysis of rotavirus vaccination, France, 2015

Two vaccines available for protection against rotavirus gastroenteritis (RVGE), Rotarix and RotaTeq, have contributed to a large decrease in the incidence of paediatric diarrhoea in countries where they have been used. However, they have also led to a small increase in the risk of intussusception. Methods: We compare the number of prevented hospitalisations for RVGE to the number of vaccine-induced hospitalised intussusceptions in France. Results: With 9.5% coverage (French 2015 estimation), vaccination was estimated to prevent, annually, a median of 1,074 hospitalisations (2.5th and 97.5th percentiles (2.5th–97.5th): 810–1,378) and 1.4 deaths (2.5th–97.5th: 1.2–1.6) from RVGE. It was also estimated to cause, annually, 5.0 hospitalisations (2.5th–97.5th: 3.2–7.7) and 0.005 deaths (2.5th–97.5th: 0.001–0.015) from intussusception. The benefit–risk ratio is therefore 214 (2.5th–97.5th: 128–362) for hospitalisations and 273 (2.5th–97.5th: 89–1,228) for deaths. Under a hypothetical 92% coverage, rotavirus vaccination with Rotarix would avoid 10,459 (2.5th–97.5th: 7,702–13,498) hospitalisations for RVGE and induce 47.0 (2.5th–97.5th: 25.1–81.4) hospitalisations for intussusception annually, thereby preventing 13.7 (2.5th–97.5th: 11.1–15.2) deaths and inducing 0.05 (2.5th–97.5th: 0.01–0.15) deaths. Conclusion: The benefit–risk ratio in France is similar to that of other European countries.

Respiratory syncytial virus tracking using internet search engine data

Background

Respiratory Syncytial Virus (RSV) is the leading cause of hospitalization in children less than 1 year of age in the United States. Internet search engine queries may provide high resolution temporal and spatial data to estimate and predict disease activity.

Methods

After filtering an initial list of 613 symptoms using high-resolution Bing search logs, we used Google Trends data between 2004 and 2016 for a smaller list of 50 terms to build predictive models of RSV incidence for five states where long-term surveillance data was available. We then used domain adaptation to model RSV incidence for the 45 remaining US states.

Results

Surveillance data sources (hospitalization and laboratory reports) were highly correlated, as were laboratory reports with search engine data. The four terms which were most often statistically significantly correlated as time series with the surveillance data in the five state models were RSV, flu, pneumonia, and bronchiolitis. Using our models, we tracked the spread of RSV by observing the time of peak use of the search term in different states. In general, the RSV peak moved from south-east (Florida) to the north-west US.

Conclusions

Our study represents the first time that RSV has been tracked using Internet data results and highlights successful use of search filters and domain adaptation techniques, using data at multiple resolutions. Our approach may assist in identifying spread of both local and more widespread RSV transmission and may be applicable to other seasonal conditions where comprehensive epidemiological data is difficult to collect or obtain.

Efficacy, safety and effectiveness of licensed rotavirus vaccines: a systematic review and meta-analysis for Latin America and the Caribbean

BACKGROUND

RotaTeq™ (RV5; Merck & Co. Inc., USA) and Rotarix™ (RV1, GlaxoSmithKline, Belgium) vaccines, developed to prevent rotavirus diarrhea in children under five years old, were both introduced into national immunization programs in 2006. As many countries in Latin America and the Caribbean have included either RV5 or RV1 in their routine childhood vaccination programs, we conducted a systematic review and meta-analysis to analyze efficacy, safety and effectiveness data from the region.

METHODS

We conducted a systematic search in PubMed, EMBASE, Scielo, Lilacs and the Cochrane Central Register, for controlled efficacy, safety and effectiveness studies published between January 2000 until December 2011, on RV5 and RV1 across Latin America (where both vaccines are available since 2006). The primary outcome measures were: rotavirus-related gastroenteritis of any severity; rotavirus emergency department visits and hospitalization; and severe adverse events.

RESULTS

The results of the meta-analysis for efficacy show that RV1 reduced the risk of any-severity rotavirus-related gastroenteritis by 65% (relative risk (RR) 0.35, 95% confidence interval (CI) 0.25; 0.50), and of severe gastroenteritis by 82% (RR 0.18, 95%CI 0.12; 0.26) versus placebo. In trials, both vaccines significantly reduced the risk of hospitalization and emergency visits by 85% (RR 0.15, 95%CI 0.09; 0.25) for RV1 and by 90% (RR 0.099, 95%CI 0.012; 0.77) for RV5. Vaccination with RV5 or RV1 did not increase the risk of death, intussusception, or other severe adverse events which were previously associated with the first licensed rotavirus vaccine. Real-world effectiveness studies showed that both vaccines reduced rotavirus hospitalization in the region by around 45-50% for RV5 (for 1 to 3 doses, respectively), and, by around 50-80% for RV1 (for 1 to 2 doses, respectively). For RV1, effectiveness against hospitalization was highest (around 80-96%) for children vaccinated before 12 months of age, compared with 5-60% effectiveness in older children. Both vaccines were most effective in preventing more severe gastroenteritis (70% for RV5 and 80-90% for RV1) and severe gastroenteritis (50% for RV5 and 70-80% for RV1).

CONCLUSION

This systematic literature review confirms rotavirus vaccination has been proven effective and well tolerated in protecting children in Latin America and the Caribbean.

Post-Marketing Benefit-Risk Assessment of Rotavirus Vaccination in Japan: A Simulation and Modelling Analysis

Introduction

Rotarix™, GSK’s live attenuated rotavirus vaccine, was introduced in Japan in 2011. A recent trend in reduction of rotavirus gastroenteritis (RVGE) due to this vaccine was described. However, an observed/expected analysis showed a temporal association with intussusception within 7 days post dose 1.

Objective

In this paper, we compare the benefit and risk of vaccination side-by-side in a benefit–risk analysis.

Methods

The number of vaccine-preventable RVGE-associated hospitalizations and deaths (benefit) and intussusception-associated hospitalizations and deaths (risk) following two doses of Rotarix™ in Japan was compared using simulations. Source data included peer-reviewed clinical and epidemiological publications, Japanese governmental statistics (Statistics Bureau, Ministry of Internal Affairs and Communications), and market survey data.

Results

For a birth cohort of 1 million vaccinated Japanese children followed for 5 years, the benefit–risk analysis suggested that the vaccine would prevent ~17,900 hospitalizations and ~6.3 deaths associated with RVGE. At the same time, vaccination would be associated with about ~50 intussusception hospitalizations and ~0.017 intussusception deaths. Therefore, for every intussusception hospitalization caused by vaccination and for one intussusception-associated death, 350 (95 % CI 69–2510) RVGE-associated hospitalizations and 366 (95 % CI 59–3271) RVGE-associated deaths are prevented, respectively, by vaccination.

Conclusions

The benefit–risk balance for Rotarix™ is favorable in Japan. From a public health perspective, the benefits in terms of prevented RVGE hospitalizations and deaths for the vaccinated population far exceed the estimated risks due to intussusception.

Electronic supplementary material

The online version of this article (doi:10.1007/s40264-015-0376-7) contains supplementary material, which is available to authorized users.

Issues in pediatric vaccine-preventable diseases in low- to middle-income countries

The highest burden of pediatric vaccine-preventable disease is found in developing nations where resource constraints pose the greatest challenge, impacting disease diagnosis and surveillance as well as the implementation of large scale vaccination programmes. In November 2012, a Working Group Meeting convened in Casablanca to describe and discuss the status with respect to 8 vaccine-preventable diseases (pertussis, pneumococcal disease, measles-mumps-rubella-varicella (MMRV), rotavirus and meningococcal meningitis) to identify and consider ways of overcoming obstacles to pediatric vaccine implementation. Experts from Europe, Russia, the Commonwealth of Independent States, the Middle East, Africa and South East Asia participated in the meeting. A range of region-specific needs and barriers to uptake were discussed. The aim of this article is to provide a summary of the ongoing status with respect to pediatric vaccine preventable disease in the countries represented, and the experts' opinions and recommendations with respect to pediatric vaccine implementation.

Molecular characterisation of the NSP4 gene of group A human rotavirus G2P[4] strains circulating in São Paulo, Brazil, from 1994 and 2006 to 2010

Group A human rotaviruses (HuRVA) are causative agents of acute gastroenteritis. Six viral structural proteins (VPs) and six nonstructural proteins (NSPs) are produced in RV-infected cells. NSP4 is a diarrhoea-inducing viral enterotoxin and NSP4 gene analysis revealed at least 15 (E1-E15) genotypes. This study analysed the NSP4 genetic diversity of HuRVA G2P[4] strains collected in the state of São Paulo (SP) from 1994 and 2006-2010 using reverse transcription-polymerase chain reaction, sequencing and phylogenetic analysis. Forty (97.6%) G2P[4] strains displayed genotype E2; one strain (2.4%) displayed genotype E1. These results are consistent with the proposed linkage between VP4/VP7 (G2P[4]) and the NSP4 (E2) genotype of HuRVA. NSP4 phylogenetic analysis showed distinct clusters, with grouping of most strains by their genotype and collection year, and most strains from SP were clustered together with strains from other Brazilian states. A deduced amino acid sequence alignment for E2 showed many variations in the C-terminal region, including the VP4-binding domain. Considering the ability of NSP4 to generate host immunity, monitoring NSP4 variations, along with those in the VP4 or VP7 protein, is important for evaluating the circulation and pathogenesis of RV. Finally, the presence of one G2P[4]E1 strain reinforces the idea that new genotype combinations emerge through reassortment and independent segregation.

Risk of Intussusception After Rotavirus Vaccination: Meta-analysis of Postlicensure Studies

BACKGROUND

Postlicensure surveillance studies suggest a small temporal increase in the risk for intussusception with both currently available rotavirus vaccines (RV1; Rotarix, GSK and RV5; RotaTeq, Merck & Co., Inc.). This meta-analysis was undertaken to provide a single overall estimate of the relative risk of intussusception during the 7-day period after administration of RV1 and RV5.

METHODS

Meta-analysis based on estimates of relative risk and corresponding 95% confidence intervals from 5 postlicensure studies providing an estimate of risk of intussusception during the 7-day period after administration of dose 1 and/or dose 2 of RV1 and/or RV5, based on active and/or passive surveillance, for confirmed intussusception cases (Brighton or other method of case confirmation). For each vaccine, the relative risk of intussusception was estimated postdose 1 and postdose 2. Results were pooled using the inverse variance method using both fixed-effect and random-effect models.

RESULTS

The overall estimate of relative risk of intussusception during the 7 days postdose 1 was 5.4 (95% confidence interval: 3.9-7.4, 3 studies) for RV1 and 5.5 (3.3-9.3, 3 studies) for RV5. The overall estimate of relative risk of intussusception during the 7 days postdose 2 was 1.8 (1.3-2.5, 4 studies) for RV1 and 1.7 (1.1-2.6, 3 studies) for RV5.

CONCLUSIONS

This meta-analysis showed a similar increased risk of intussusception, during the first 7 days after administration of dose 1 and, to a lesser extent, dose 2, for both currently available rotavirus vaccines. This suggests that intussusception may be a class effect of currently available oral rotavirus vaccines.

Rotavirus vaccination in Brazil: effectiveness and health impact seven years post-introduction

Before vaccine introduction in Brazil, rotavirus caused approximately 650,000 outpatient visits, 92,000 hospitalizations and 850 deaths annually among children aged <5 years. Brazil was one of the first countries to introduce rotavirus vaccination into the National Immunisation Program (NIP), in 2006, but estimated coverage (87.1%) for 2011 remained lower if compared with other routine immunizations (95%). Case-control studies reached effectiveness rates as high as 85%. Observational studies showed a significant reduction in gastroenteritis-related hospitalizations and deaths among children aged <1 year, at rates as high as 48 and 54%, respectively. There was a significant increase in the relative prevalence of G2P[4] genotype after vaccine introduction, reaching 100% of strains in some settings. A small increase in intussusception incidence was seen within 1 week following the second vaccine dose, but benefits far outweigh any potential risk. This article provides an in-depth review of postlicensure studies conducted in Brazil 7-year postintroduction.

Routine childhood vaccination programme coverage, El Salvador, 2011-In search of timeliness

While assessing immunization programmes, not only vaccination coverage is important, but also timely receipt of vaccines. We estimated both vaccination coverage and timeliness, as well as reasons for non-vaccination, and identified predictors of delayed or missed vaccination, for vaccines of the first two years of age, in El Salvador. We conducted a cluster survey among children aged 23-59 months. Caregivers were interviewed about the child immunization status and their attitudes towards immunization. Vaccination dates were obtained from children immunization cards at home or at health facilities. We referred to the 2006 vaccination schedule for children below two years: one dose of BCG (Bacillus Calmette-Guérin) at birth; rotavirus at two and four months; three doses of pentavalent - DTP (diphtheria-tetanus-pertussis), hepatitis B, and Haemophilus influenzae type b (Hib) - and of oral poliomyelitis vaccine (polio) at two, four, and six months; first MMR (measles-mumps-rubella) at 12 months; and first boosters of DTP and OPV at 18 months. Timeliness was assessed with Kaplan-Meier analysis; Cox and logistic regression were used to identify predictors of vaccination. We surveyed 2550 children. Coverage was highest for BCG (991%; 95% CI: 98.8-99.5) and lowest for rotavirus, especially second dose (86.3%; 95% CI: 84.2-88.4). The first doses of MMR and DTP had 991% (95% CI: 98.5-99.6) and 977% (95% CI: 970-985), respectively. Overall coverage was 837% (95% CI: 81.4-86.0); 96.4% (95% CI: 95.4-97.5), excluding rotavirus. However, only 26.7% (95% CI: 24.7-28.8) were vaccinated within the age interval recommended by the Expanded Programme on Immunization. Being employed and using the bus for transport to the health facility were associated with age-inappropriate vaccinations; while living in households with only two residents and in the "Paracentral", "Occidental", and "Oriental" regions was associated with age-appropriate vaccinations. Vaccination coverage was high in El Salvador, but general timeliness and rotavirus uptake could be improved.

The human rotavirus vaccine Rotarix™ in infants: an integrated analysis of safety and reactogenicity

An integrated analysis of safety and reactogenicity data was undertaken for 28 randomized, placebo-controlled, double-blind Phase II and III trials (DBRCTs) of the oral live-attenuated human rotavirus vaccine, Rotarix™ (GlaxoSmithKline Vaccines). Healthy infants aged 6-20 wk received 2 or 3 doses of vaccine (n=56562) or placebo (n=45512) at 4- to 8-wk intervals. Solicited adverse events (AEs) were recorded for 8 d after each dose of vaccine or placebo. Unsolicited AEs, serious AEs (SAEs), and deaths were evaluated over 31-d post-vaccination follow-up periods. 95% confidence intervals (CIs) for the relative risk (RR) across studies excluding "1.0" signified potential imbalances between the 2 groups. The incidence of each solicited AE of any or Grade 3 severity was similar between groups. The incidence of all unsolicited AEs of any (RR=0.99 [95% CI: 0.94-1.04]; P=0.72) or Grade 3 severity (RR=0.91 [95% CI: 0.77-1.08]; P=0.31) was similar between groups. A significantly higher proportion of SAEs were reported in the placebo group compared with the vaccine group (RR=0.9 [95% CI: 0.82-0.98]; P=0.01). The incidence of death was low and similar between the 2 groups (0.13% in the vaccine group and 0.11% in the placebo group; RR=1.14 [95% CI: 0.78-1.68]; P=0.54). Very few cases of intussusception were reported (11 and 7 in the vaccine and placebo groups, respectively; RR=1.39 [95% CI: 0.49-4.27]; P=0.66). In conclusion, results of this analysis of DBRCTs show that the human rotavirus vaccine Rotarix™ has a reactogenicity and safety profile similar to placebo.

Incidence of intussusception in Singaporean children aged less than 2 years: a hospital-based prospective study

Background

Continuous surveillance for intussusception (IS) is important for monitoring the safety of second-generation rotavirus vaccines. The present study aimed to assess the incidence of IS in Singaporean children aged < 2 years.

Methods

This was a prospective, hospital-based, multi-center surveillance conducted in seven hospitals - two public hospitals and five private medical centers between May 2002 and June 2010 in Singapore. Diagnosis of IS (definite, probable, possible, suspected) was based on the case definition developed by the Brighton Collaboration. Children < 2 years of age who were diagnosed with IS were enrolled in this study. Incidence of IS was calculated per 100,000 child-year with its 95% confidence interval.

Results

Of the 178 children enrolled, 167 children with definite IS cases were considered for final analyses; 11 were excluded (six diagnosed as probable IS and four diagnosed as suspected IS; one child’s parents withdrew consent). Mean age of children with definite IS was 11.6 ± 6 months; 67.7% were males. The overall incidence of IS was 28.9 (95% CI: 23.0–34.8) and 26.1 (95% CI: 22.2–30.0) per 100,000 child-year in children < 1 year and < 2 years of age, respectively. The majority of IS cases (20 [12.0%]) were reported in children aged 6 months. Most children (98.2% [164/167]) recovered, two (1.2%) children recovered with sequelae and one (0.6%) child died of septic shock.

Conclusions

The incidence of IS remained low and stable in Singaporean children aged < 2 years during the study period (May 2002 to June 2010).

Trial registration

NCT01177839

Efficacy, immunogenicity, and safety of two doses of a tetravalent rotavirus vaccine RRV-TV in Ghana with the first dose administered during the neonatal period

BACKGROUND

Oral rhesus/rhesus-human reassortant rotavirus tetravalent vaccine (RRV-TV) was licensed in 1998 but withdrawn in 1999 due to a rare association with intussusception, which occurred disproportionately in infants receiving their first dose at ≥90 days of age. This study examined RRV-TV for the prevention of rotavirus gastroenteritis (RV-GE) in Ghana, West Africa, with infants receiving the first dose during the neonatal period and the second before 60 days of age.

METHODS

In a double-blinded, randomized, placebo-controlled trial in Navrongo, Ghana, we recruited neonates to receive 2 doses of RRV-TV or placebo and followed them to age 12 months.

RESULTS

In the intention-to-treat population of 998 infants, we measured a vaccine efficacy of 63.1% against RV-GE of any severity associated with any of the 4 serotypes represented in the vaccine and 60.7% against RV-GE associated with any rotavirus serotype.

CONCLUSIONS

RRV-TV in a 2-dose schedule with the first dose during the neonatal period is efficacious in preventing RV-GE in rural Ghana. Neonatal dosing results in early protection and may be the optimum schedule to avoid or significantly reduce intussusception, now reported to be associated in international settings with the 2 most widely marketed, licensed, live virus, oral rotavirus vaccines.

A multi-country study of intussusception in children under 2 years of age in Latin America: analysis of prospective surveillance data

BACKGROUND

Intussusception (IS) is a form of acute intestinal obstruction that occurs mainly in infants and is usually of unknown cause. An association between IS and the first licensed rotavirus vaccine, a reassortant-tetravalent, rhesus-based rotavirus vaccine (RRV-TV), led to the withdrawal of the vaccine. New rotavirus vaccines have now been developed and extensively studied for their potential association with IS. This study aimed to describe the epidemiology and to estimate the incidence of IS in Latin American infants prior to new vaccine introduction.

METHODS

Children under 2 years of age representing potential IS cases were enrolled in 16 centers in 11 Latin American countries from January 2003 to May 2005. IS cases were classified as definite, probable, possible or suspected as stated on the Brighton Collaboration Working Group guidelines.

RESULTS

From 517 potential cases identified, 476 (92%) cases were classified as definite, 21 probable, 10 possible and 10 suspected for intussusception. Among the 476 definite IS cases, the median age at presentation was 6.4 months with 89% of cases aged <1 year. The male to female ratio was 1.5:1. The incidence of definite IS per 100,000 subject-years ranged from 1.9 in Brazil to 62.4 in Argentina for children <2 years of age, and from 3.8 in Brazil to 105.3 in Argentina for children aged <1 year. Median hospital stay was 4 days with a high prevalence of surgery as the primary treatment (65%). Most cases (88%) made a complete recovery, but 13 (3%) died. No clear seasonal pattern of IS cases emerged.

CONCLUSIONS

This study describes the epidemiology and estimates the incidence of IS in Latin American infants prior to the introduction of new rotavirus vaccines. The incidence of IS was found to vary between different countries, as observed in previous studies.

TRIAL REGISTRATION

Clinical study identifier 999910/204 (SERO-EPI-IS-204).

Diversity of rotavirus strains circulating in children under 5 years of age admitted to hospital for acute gastroenteritis in Morocco, June 2006 to May 2009

Rotavirus vaccine was introduced in Morocco during 2010. In anticipation of introducing rotavirus vaccines, the Ministry of Health in Morocco established a rotavirus surveillance network in June 2006 at four hospitals in Morocco to obtain baseline data on rotavirus disease burden and prevalent strains. From June 2006 to May 2009, stool samples were collected from children under 5 years of age admitted for diarrhea to four sentinel hospitals serving different regions of Morocco. Rotaviruses were detected in stools using enzyme immunoassay, then genotyped by reverse-transcriptase polymerase chain reaction. Samples with adequate stool in which the P or G types could not be determined by RT-PCR were subjected to nucleotide sequence analysis. Overall, 42% (579 of 1,388) of the stools samples tested were positive for rotavirus. Genotyping of 548 (95%) samples demonstrated that G1P[8] (55%) was the most prevalent strain, followed by G9P[8] (11.3%), G2P[4] (9.1%), G4P[8] (0.9%), and G3P[8] (0.4%). Several other strains were identified including G1P[4] (0.2%), G1P[6] (0.9%), G2P[6] (4.3%), G2P[8] (0.2%), G3P[6] (0.4%), G3P[4] (0.2%), and G9P[6] (0.2%). A high prevalence of mixed infections was found (15% of all samples) of which G1G2P[8] (4%) and G1G3P[8] (3.6%) accounted for the majority. Considerable diversity of rotavirus genotypes was present among strains circulating in Morocco prior to the introduction of the vaccine. This study highlighted the need for maintaining active surveillance to monitor changes in rotavirus disease burden and strain dynamics and to detect changes over time that could impact the effectiveness of the vaccination program.