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

Review of Over 15 Years Postmarketing Safety Surveillance Spontaneous Data for the Human Rotavirus Vaccine (Rotarix) on Intussusception

Introduction

Rotavirus (RV) is the most common cause of acute gastroenteritis in children <5 years of age worldwide, and vaccination reduces the disease burden. Evidence from postmarketing surveillance studies suggested an increased risk of intussusception (IS) in infants post-RV vaccination. An overall positive benefit–risk balance for the human RV vaccine (HRV) Rotarix (GlaxoSmithKline [GSK], Belgium) has been established and recent findings indicate an indirect effect of reduced IS over the long term.

Objective

The aim of this study was to discuss spontaneous data from the GSK worldwide safety database on IS post-Rotarix administration.

Methods

The database was reviewed for all spontaneous IS cases from 2004 to 2020. Additionally, an observed versus expected (O/E) analysis was done for adverse events attributed to IS. Data were reviewed as overall worldwide and stratified by region (Europe/USA/Japan) and dose.

Results

A male predominance of IS patients was observed, consistent with earlier reports. The most frequently reported events in confirmed IS cases (Brighton Collaboration Working Group [BCWG] level 1) with time to onset ≤ 30 days post-vaccination were vomiting (55.8%), haematochezia (47.2%), and crying (21.1%). The observations from the IS spontaneous cases review and results of the O/E analysis are consistent with the known IS safety profile of RV vaccines: a transient increased incidence of IS post-vaccination (primarily in Europe/Japan/worldwide), mostly within 7 days postdose 1.

Conclusion

Since the outcomes of early IS management are favourable over delayed management, healthcare professionals should inform parents about the importance of seeking immediate medical advice in case of unusual behaviour of the vaccinated infant. GSK continues to monitor the IS risk post-Rotarix administration through routine pharmacovigilance activities.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40264-021-01141-4.

Rotavirus (RV) is the most common cause of acute gastroenteritis and a major cause of death in young children worldwide. Vaccination has been instrumental in reducing the impact of RV disease. Real-world evidence suggests an increased risk of intussusception (an infrequent type of bowel obstruction) in infants following RV vaccination. We reviewed IS cases reported spontaneously worldwide in children following a two-dose vaccination with the human RV vaccine (Rotarix, GlaxoSmithKline [GSK]) since its launch in 2004. We observed that (1) IS occurred more frequently 7 days after the first dose and, to a lesser extent, after the second dose; (2) boys were more frequently affected than girls (56.3%); (3) of 862 confirmed reported cases, 557 required hospitalisation; and (4) surgical intervention was required for 294 of 557 hospitalised cases. We used statistical analysis to assess whether the number of cases observed would be higher or lower than the natural occurrence of IS (irrespective of vaccination). These results were in line with the known RV vaccine safety profile. It is important to constantly monitor the real-world safety profile of RV vaccines in the postmarketing setting. Since the outcomes of early management of IS are favourable compared with delayed management, healthcare professionals should inform parents to seek immediate medical advice if they observe unusual behaviour in their vaccinated child. In conclusion, our analyses on data of a large patient pool for this rare event reinforce the favourable safety profile of human RV vaccine and the benefits of vaccination in young children.

Characteristics of intussusception in the period of arbitrary Rotavirus vaccination

BACKGROUND

In November 2011, rotavirus (RV) vaccine was launched in Japan as a voluntary vaccination to prevent RV-associated gastroenterocolitis. We examined the characteristics of intussusception following RV vaccination in our two centers.

METHODS

We investigated intussusception patients <16 years old from January 2006 to September 2020. Patients were categorized according to the period (before [Group A] or after the introduction of arbitrary RV vaccination [Group B]). The patient characteristics and treatment of intussusception were retrospectively investigated.

RESULTS

During the study period, 560 patients (group A, n = 233; group B, n = 327) were identified. The distribution of patients who were 0-6 months old was not significantly different between the groups (group A, n = 12, 5.2%; group B, n = 18, 5.5%). Among these 18 patients in Group B, 7 were vaccinated against RV, and 10 were not. One patient was excluded due to incomplete data. On comparing patients with and without RV vaccination, the mean age at the onset of intussusception was 3.3 ± 0.4 versus 4.0 ± 0.3 months (P = 0.19), the mean interval from the onset to treatment was 7.5 ± 2.4 versus 16.0 ± 2.2 h (P = 0.03), the time of the contrast enema for treatment was 9.1 ± 3.3 versus 7.7 ± 2.8 min (P = 0.76), and the final pressure of the contrast enema was 92.5 ± 4.4 versus 92.2 ± 4.4 cmH₂ O (P = 0.97).

CONCLUSIONS

Arbitrary RV vaccination did not influence the age distribution of intussusception, and the interval from the onset to treatment was significantly shorter in the patients with RV vaccination than in those without it. Recognizing the presence of intussusception following RV vaccination enables accurate treatment.

Effectiveness of self-financed rotavirus vaccination in Ise City, Japan

In Japan, the herd immunity effect of rotavirus vaccine has not yet been proven. Here, we conducted active surveillance for hospitalization due to rotavirus acute gastroenteritis (AGE) among children under 5 years of age in pre-rotavirus vaccination years and self-financed rotavirus vaccination years to clarify the rotavirus vaccine effectiveness (VE) in reducing hospitalization rates. A time-series analysis showed that the monthly hospitalization rates observed after vaccine introduction were significantly lower than the forecasted hospitalization rates (p < .001, Mann-Whitney U test). In the third year after vaccine introduction, the hospitalization rate declined despite the low vaccination rate of 27-50% for the two preceding years. We estimated four types of VE, namely direct, indirect, total, and overall. The direct VE was calculated from the relative risk ratio of hospitalizations between vaccinated and unvaccinated children. The indirect VE was defined as the population-level effects of vaccination on children not receiving the vaccine. The total VE was defined as the combination of the direct and indirect VE on children receiving the vaccine. The overall VE was determined by the weighted average of indirect VE on the children not receiving the vaccine and the total VE on the children receiving the vaccine. The direct, indirect, total, and overall VE values were calculated as 82% (95% confidence interval, 52-93), 70% (51-82), 95% (87-98), and 86% (77-91), respectively. The high values of indirect, total, and overall VE indicate that the rotavirus vaccine produces a herd immunity effect.

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.

Implementing vaccination policies based upon scientific evidence in Japan

The theme of the 24th Annual Meeting of the Japanese Society for Vaccinology was “Sustainable Future Medical Care Created by Vaccines.” This theme includes topics such as the proposal to reduce the medical costs incurred by societies with aging populations through prophylactic vaccination. The coronavirus disease 2019 (COVID-19) pandemic alerted us to the important roles that preventive measures, such as vaccines, play in fighting infectious diseases. In order to inform the public of the benefits of vaccines, it is important to provide society with information regarding new vaccine developments, adjuvants, the cost–benefit ratio of vaccine introduction, and vaccine effectiveness and safety. Clinical research is essential for obtaining evidence of vaccine effectiveness and safety. The United States Centers for Disease Control and Prevention (CDC) conducts active surveillance in defined areas before and after the introduction of vaccines and documents the reduction in infection rates as a measure of vaccine effectiveness. However, vaccine efficacy and side effects may vary by country and ethnicity. Therefore, it is necessary for individual countries to develop their own evidence-based surveillance programs. We have studied vaccine efficacy and documented side-effects observed in patients for the varicella and rotavirus vaccines in Japan. This review outlines the importance of providing scientific evidence for vaccine effectiveness and safety.

Economic evaluation of the introduction of rotavirus vaccine in Hong Kong

BACKGROUND

Rotavirus is a common cause of severe gastroenteritis in young children in Hong Kong (HK) with a high economic burden. This study aimed to evaluate the cost-effectiveness of introducing rotavirus vaccination into the HK Government's Childhood Immunisation Programme (CIP) and to include the potential protective effect of the vaccine against seizures.

METHODS

A decision-support model was customised to estimate the potential impact, cost-effectiveness and benefit-risk of rotavirus vaccination in children below 5 years over the period 2020-2029 in HK. Two doses of Rotarix® and three doses of RotaTeq® were each compared to no vaccination. Rotavirus treatment costs were calculated from a governmental health sector perspective (i.e., costs of public sector treatment) and an overall health sector perspective (both governmental and patient, i.e., costs of public sector treatment, private sector treatment, transport and diapers). We ran probabilistic and deterministic uncertainty analyses.

RESULTS

Introduction of rotavirus vaccination in HK could prevent 49,000 (95% uncertainty interval: ~44,000-54,000) hospitalisations of rotavirus gastroenteritis and seizures and result in ~50 (95% uncertainty interval: ~25-85) intussusception hospitalisations, over the period 2020-2029 (a benefit-risk ratio of ~1000:1), compared to a scenario with no public or private sector vaccine use. The discounted vaccination cost would be US$51-57 million over the period 2020-2029 based on per-course prices of US$72 (Rotarix®) or US$78 (RotaTeq®), but this would be offset by discounted treatment cost savings of US$70 million (government) and US$127 million (governmental and patient health sector). There was a greater than 94% probability that the vaccine could be cost-saving irrespective of the vaccine product or perspective considered. All deterministic 'what-if' scenarios were cost-saving from an overall health sector perspective (governmental and patient).

CONCLUSIONS

Rotavirus vaccination is likely to be cost-saving and have a favourable benefit-risk profile in HK. Based on the assumptions made, our analysis supports its introduction into CIP.

Benefit-Risk Assessment of Vaccines. Part II: Proposal Towards Consolidated Standards of Reporting Quantitative Benefit-Risk Models Applied to Vaccines (BRIVAC)

INTRODUCTION

Quantitative benefit-risk models (qBRm) applied to vaccines are increasingly used by public health authorities and pharmaceutical companies as an important tool to help decision makers with supporting benefit-risk assessment (BRA). However, many publications on vaccine qBRm provide insufficient details on the methodological approaches used. Incomplete and/or inadequate qBRm reporting may affect result interpretation and confidence in BRA, highlighting a need for the development of standard reporting guidance.

OBJECTIVES

Our objective was to provide an operational checklist for improved reporting of vaccine qBRm.

METHODS

The consolidated standards of reporting quantitative Benefit-RIsk models applied to VACcines (BRIVAC) were designed as a checklist of key information to report in qBRm scientific publications regarding the assessed vaccines, the methodological considerations and the results and their interpretation.

RESULTS

In total, 22 items and accompanying definitions, recommendations, explanations and examples were provided and divided into six main sections corresponding to the classic subdivisions of a scientific publication: title and abstract (items 1-2), introduction (items 3-4), methods (items 5-15), results (items 16-17), discussion (items 18-20) and other (items 21-22).

CONCLUSIONS

The BRIVAC checklist is the first initiative providing an operational checklist for improved reporting of qBRm applied to vaccines in scientific articles. It is intended to assist authors, peer-reviewers, editors and readers in their critical appraisal. Future initiatives are needed to provide methodological guidance to perform qBRm while taking into account the vaccine specificities.

Accounting for indirect protection in the benefit-risk ratio estimation of rotavirus vaccination in children under the age of 5 years, France, 2018

Background Rotavirus is a major cause of severe gastroenteritis in children worldwide. The disease burden has been substantially reduced in countries where rotavirus vaccines are used. Given the risk of vaccine-induced intussusception, the benefit–risk balance of rotavirus vaccination has been assessed in several countries, however mostly without considering indirect protection effects. Aim We performed a benefit–risk analysis of rotavirus vaccination accounting for indirect protection in France among the 2018 population of children under the age of 5 years. Methods To incorporate indirect protection effects in the benefit formula, we adopted a pseudo-vaccine approach involving mathematical approximation and used a simulation design to provide uncertainty intervals. We derived background incidence distributions from quasi-exhaustive health claim data. We examined different coverage levels and assumptions regarding the waning effects and intussusception case fatality rate. Results With the current vaccination coverage of < 10%, the indirect effectiveness was estimated at 6.4% (+/− 0.4). For each hospitalisation for intussusception, 277.0 (95% uncertainty interval: (165.0–462.1)) hospitalisations for rotavirus gastroenteritis were prevented. Should 90% of infants be vaccinated, indirect effectiveness would reach 57.9% (+/− 3.7) and the benefit–risk ratio would be 192.4 (95% uncertainty interval: 116.4–321.3). At a coverage level of 50%, indirect protection accounted for 27% of the prevented rotavirus gastroenteritis cases. The balance remained in favour of the vaccine even in a scenario with a high assumption for intussusception case fatality. Conclusions These findings contribute to a better assessment of the rotavirus vaccine benefit–risk balance.

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.

Benefit-Risk Monitoring of Vaccines Using an Interactive Dashboard: A Methodological Proposal from the ADVANCE Project

INTRODUCTION

New vaccines are launched based on their benefit-risk (B/R) profile anticipated from clinical development. Proactive post-marketing surveillance is necessary to assess whether the vaccination uptake and the B/R profile are as expected and, ultimately, whether further public health or regulatory actions are needed. There are several, typically not integrated, facets of post-marketing vaccine surveillance: the surveillance of vaccination coverage, vaccine safety, effectiveness and impact.

OBJECTIVE

With this work, we aim to assess the feasibility and added value of using an interactive dashboard as a potential methodology for near real-time monitoring of vaccine coverage and pre-specified health benefits and risks of vaccines.

METHODS

We developed a web application with an interactive dashboard for B/R monitoring. The dashboard is demonstrated using simulated electronic healthcare record data mimicking the introduction of rotavirus vaccination in the UK. The interactive dashboard allows end users to select certain parameters, including expected vaccine effectiveness, age groups, and time periods and allows calculation of the incremental net health benefit (INHB) as well as the incremental benefit-risk ratio (IBRR) for different sets of preference weights. We assessed the potential added value of the dashboard by user testing amongst a range of stakeholders experienced in the post-marketing monitoring of vaccines.

RESULTS

The dashboard was successfully implemented and demonstrated. The feedback from the potential end users was generally positive, although reluctance to using composite B/R measures was expressed.

CONCLUSION

The use of interactive dashboards for B/R monitoring is promising and received support from various stakeholders. In future research, the use of such an interactive dashboard will be further tested with real-life data as opposed to simulated data.

Facilitators and barriers for use of rotavirus vaccine amongst various stakeholders and its implications for Indian context - A systematic review

Background: We performed a systematic review to evaluate factors affecting uptake of rotavirus vaccine amongst physicians, parents and health system. Methods: We identified 15 studies that met the inclusion criteria from 790 screened studies published between Jan 2005 to Jan 2016. Results: Perceived severity of rotavirus disease, efficacy of vaccine and recommendation by health authorities positively influenced uptake of vaccine amongst health care providers. Routine and timely vaccination with routine vaccines and availability of rotavirus vaccine in public health programme facilitated uptake. Family income, parental education and employment status positively influenced the decision to vaccinate by parents. Concerns about safety, high cost, additional workload and logistic problems in acquiring vaccine stocks were perceived as barriers. Conclusion: Improved awareness regarding the rotavirus vaccination amongst public and scientific community and strengthening of public health system for better and timely immunisation coverage are important factors to maximize uptake of rotavirus vaccine in India.

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.

Post-rotavirus vaccine intussusception in identical twins: A case report

The intussusception is one of the most frequent causes of occlusive syndrome in infants and in children. (1) The mesenteric lymphadenopathy, wich is very rare post rotavirus vaccination, can cause intussusception, (2-5) especially in genetically predisposed individuals. (6) There is an association between intussusception and some classes of genotype. (7-9) Two infants aged 3 months, vaccinated against rotavirus. After about a week, one of the 2 identical infants presented inconsolable crying, vomiting, loose stools mixed with blood, and was diagnosed with bowel obstruction with intussusception. He was operated in urgency. After a few hours, his brother presented vomiting, and was admitted to our Hospital for suspected intussusception. The controls carried out have confirmed the presence of intussusception that was treated early, before the onset of severe symptoms. The incidence of post rotavirus vaccine intussusception is very low. The determining factor hypothetically might be linked to the presence of a genotype that exposes infants to a greater risk of developing mesenteric lymphadenitis and intussusception. In our case, the diagnosis of intussusception occurred in a twin, which allowed us to recognize early symptoms which accused the brother and schedule the surgery with less urgency. Our experience may want to sensitize families and pediatricians to report cases of intussusception given a theoretical familiar association. The study of the genotype could be decisive for or not to exclude the presence of a risk of invagination, thus avoiding vaccination.