Modelling the Public Health Burden of Herpes Zoster and the Impact of Adjuvanted Recombinant Zoster Vaccine in Five Selected Countries in Southeast Asia.

INTRODUCTION: Herpes zoster (HZ) can cause substantial patient morbidity and lead to large healthcare costs. However, the disease burden of HZ in Southeast Asia may be underestimated. This study aimed to estimate the public health burden of HZ and the impact of vaccinating adults aged ≥ 50 years old in five Southeast Asian countries (Indonesia, Malaysia, Philippines, Thailand, and Vietnam), with adjuvanted recombinant zoster vaccine (RZV) compared with no vaccination. METHODS: For each country, we adapted a static multicohort Markov model developed with a 1-year cycle length and lifetime horizon. Demographics were obtained from the World Health Organization, HZ incidence from a worldwide meta-regression reporting Asian-specific values, proportions of postherpetic neuralgia (PHN) and non-PHN complications from local/regional studies, and vaccine efficacy from a long-term follow-up trial. First-dose coverage and second-dose compliance were assumed to be 30% and 70%, respectively. A one-way deterministic sensitivity analysis (OWSA) and probabilistic sensitivity analysis (PSA) were performed to assess the robustness and uncertainty of inputs for each country. RESULTS: Without RZV, it was estimated that there would be a total of approximately 10 million HZ cases, 2.1 million PHN cases, and 1.4 million non-PHN complications in individuals aged ≥ 50 years included in the model. Introducing RZV under 30% coverage could avoid approximately 2.2 million (22%) HZ cases, almost 500,000 (21%) PHN cases, and around 300,000 (22%) non-PHN complications. OWSA showed that first-dose coverage and initial HZ incidence had the largest impact on the estimated number of HZ cases avoided. The number needed to vaccinate ranged from 15 to 21 to prevent one case of HZ and from 68 to 104 to prevent one case of PHN across each country. CONCLUSIONS: This study demonstrated that there is substantial HZ disease burden in older adults for the five selected countries in Southeast Asia, negatively impacting national healthcare systems. Introducing RZV could potentially reduce this burden. A graphical abstract is available with this article.

A review of rotavirus vaccine use in Asia and the Pacific regions: challenges and future prospects.

INTRODUCTION: Rotavirus infection causes a significant proportion of diarrhea disease burden in children <5 years of age in Asia and the Pacific regions. The World Health Organization recommends that rotavirus vaccination should be included in national immunization programs to prevent rotavirus gastroenteritis (RVGE). AREAS COVERED: A literature review was performed to identify and summarize published evidence on RVGE epidemiology and status of rotavirus vaccine use, including the impact and cost-effectiveness of rotavirus vaccination programs in Asia and the Pacific regions (49 countries) during the period 2000-2018. EXPERT OPINION: Rotavirus vaccination programs have successfully reduced the burden of RVGE in many countries. However, such programs still do not exist in most Asia-Pacific countries, and therefore the burden of RVGE remains high in children <5 years of age. Challenges to vaccine implementation include a lack of surveillance data; safety concerns around intussusception; a general lack of awareness about RVGE disease epidemiology and vaccines among physicians, policy-makers, and parents; insufficient cost-effectiveness analyses; and potential issues with vaccine affordability including vaccination costs and lack of political will. Recommendations to overcome these challenges include developing cost-effectiveness analyses for more diverse national and regional settings, providing non-governmental support for low-income countries, and improving advocacy efforts.

PLAIN LANGUAGE SUMMARYWhat is the context?Rotavirus (RV) infection causes acute gastroenteritis (GE) in children under 5 years of age.Rotavirus vaccination (RVV) implementation has been slow in Asia and the Pacific (AP) regions, which could be responsible for the region falling behind in their fight against RVGE.What is new?RVV via national immunization programs (NIPs) is available in 8/49 countries and through the private market or non-governmental support in other countries. Coverage rates vary between countries, possibly driven by the mechanism through which RVV is available.A substantial positive impact of RVV on RVGE disease burden with a very low risk of intestinal intussusception for up to 7 days after RVV has been documented in the AP regions.Economic evaluation studies, mainly cost-effectiveness analyses, predict a significant reduction in treatment costs related to RVGE and its complications showing that RVV is good value for money.What is the impact?The prospect of continued safe and effective use of RVV in the AP regions is promising.Challenges to RVV implementation include establishing evidence of burden of disease, poor awareness of rotavirus vaccines, limited evidence from cost-effectiveness analyses from several countries, issues of affordability of the vaccine and a lack of political will.Recommendations for RVV implementation into the NIPs include conducting clinical and cost-effectiveness studies in countries where these are not available, establishing reliable surveillance mechanisms, providing non-governmental support for low-income countries and improving advocacy efforts.Maintenance of high vaccination coverage is needed in countries that have implemented national RVV programs.Graphical abstract[Formula: see text].

Dynamics of G2P[4] strain evolution and rotavirus vaccination: A review of evidence for Rotarix.

Rotavirus (RV) gastroenteritis is a vaccine-preventable disease that creates high medical and economic burden in both developed and developing countries. Worldwide, more than 100 countries have introduced RV vaccines in their national immunization programs, and the remarkable impact of reducing the burden of severe childhood gastroenteritis has been unequivocally demonstrated. Currently, 2 oral vaccines (Rotarix, GSK and RotaTeq, Merck) are widely utilized. Recent temporary increases in the relative prevalence of G2P[4] RV strains have been observed in countries implementing RV vaccination. This comprehensive literature review aims to provide an insight on RV genotype evolution in the context of mass vaccination with Rotarix, particularly in the case of G2P[4]. In the post-vaccine era, strain surveillance data indicated temporal and spatial changes in countries both with and without RV vaccination programs. Annual fluctuations in G2P[4] prevalence seem to occur naturally, with no substantial differences between countries using Rotarix, RotaTeq or mixed vaccination programs. Moreover, Rotarix has been shown to be efficacious and effective against gastroenteritis caused by non-vaccine strains, including G2P[4]. These data indicate that shifts in RV genotype distribution are likely to constitute an inherent process of virus evolution to infect the human gut. Following RV vaccine introduction, incidences of RV gastroenteritis declined dramatically and mass vaccination will likely maintain this status, despite possible fluctuations in the relative distribution of genotypes. There is no conclusive evidence of unusual burst of new or vaccine-escape strains since global RV vaccines use. The emergence of strains with a potential to increase the current burden of RV disease should be continuously monitored and can only be established by exhaustive characterization of strains, including whole genomic sequencing. Given the natural fluctuations in RV strains over time, caution is advised when interpreting temporal changes in RV strain dynamics, as they could mistakenly be attributed to vaccination.

Economic Evaluation of Human Rotavirus Vaccine in Thailand.

INTRODUCTION: Rotavirus gastroenteritis is the leading cause of severe diarrhoea among young children < 5 years old. Previous cost-effectiveness analyses on rotavirus (RV) vaccination in Thailand have generated conflicting results. The aim of this current study is to evaluate the economic impact of introducing RV vaccination in Thailand, using updated Thai epidemiological and cost data. METHODS: Both cost-utility analysis (CUA) and budget impact analysis (BIA) of human rotavirus vaccine (HRV) under a universal mass vaccination (UMV) programme were conducted. A published static, deterministic, cross-sectional population model was adapted to assess costs and health outcomes associated with RV vaccination among Thai children < 5 years old during 1 year for CUA and over a 5-year period (2019-2023) for BIA. Data identified through literature review were incorporated into the model after consultation with local experts. Base case CUA was conducted from a societal perspective with quality-adjusted life year (QALY) discounted at 3% annually. Scenario analyses as well as one-way and probabilistic sensitivity analyses were conducted to assess the robustness of the base case CUA results. Costs were updated to 2017. RESULTS: At 99% coverage, HRV vaccination would substantially reduce RV-related disease burden. With an incremental cost-effectiveness ratio (ICER) of Thai baht (THB) 49,923/QALY gained, HRV vaccination versus no vaccination was cost-effective when assessed against a local threshold of THB 160,000/QALY gained. Scenario and sensitivity analyses confirmed the cost-effectiveness with all resultant ICERs falling below the willingness-to-pay threshold. HRV use in the UMV programme was estimated to result in a net expenditure of about THB 255-281 million to the Thai government in the 5th year of the programme, depending on vaccine uptake. CONCLUSION: HRV vaccination is estimated to be cost-effective in Thailand. The budget impact following inclusion of HRV into the UMV programme is expected to be partially offset by substantial reductions in RV-related disease costs. FUNDING: GlaxoSmithKline Biologicals SA GSK STUDY IDENTIFIER: HO-17-18213.