Hypothetical emergence of poliovirus in 2020: part 1. Consequences of policy decisions to respond using nonpharmaceutical interventions

Review of Poliovirus Transmission and Economic Modeling to Support Global Polio Eradication: 2020-2024

Continued investment in the development and application of mathematical models of poliovirus transmission, economics, and risks leads to their use in support of polio endgame strategy development and risk management policies. This study complements an earlier review covering the period 2000-2019 and discusses the evolution of studies published since 2020 by modeling groups supported by the Global Polio Eradication Initiative (GPEI) partners and others. We systematically review modeling papers published in English in peer-reviewed journals from 2020-2024.25 that focus on poliovirus transmission and health economic analyses. In spite of the long-anticipated end of poliovirus transmission and the GPEI sunset, which would lead to the end of its support for modeling, we find that the number of modeling groups supported by GPEI partners doubled and the rate of their publications increased. Modeling continued to play a role in supporting GPEI and national/regional policies, but changes in polio eradication governance, decentralized management and decision-making, and increased heterogeneity in modeling approaches and findings decreased the overall impact of modeling results. Meanwhile, the failure of the 2016 globally coordinated cessation of type 2 oral poliovirus vaccine use for preventive immunization and the introduction of new poliovirus vaccines and formulation, increased the complexity and uncertainty of poliovirus transmission and economic models and policy recommendations during this time.

Pandemic refuges: Lessons from 2 years of COVID-19

This paper relates evidence from the COVID-19 pandemic to the concept of pandemic refuges, as developed in literature on global catastrophic risk. In this literature, a refuge is a place or facility designed to keep a portion of the population alive during extreme global catastrophes. COVID-19 is not the most extreme pandemic scenario, but it is nonetheless a very severe global event, and it therefore provides an important source of evidence. Through the first 2 years of the COVID-19 pandemic, several political jurisdictions have achieved low spread of COVID-19 via isolation from the rest of the world and can therefore classify as pandemic refuges. Their suppression and elimination of COVID-19 demonstrates the viability of pandemic refuges as a risk management measure. Whereas prior research emphasizes island nations as pandemic refuges, this paper uses case studies of China and Western Australia to show that other types of jurisdictions can also successfully function as pandemic refuges. The paper also refines the concept of pandemic refuges and discusses implications for future pandemics.

Health economic analysis of vaccine options for the polio eradication endgame: 2022-2036

BACKGROUND

: Multiple vaccine options are available for polio prevention and risk management. Integrated global risk, economic, and poliovirus transmission modeling provides a tool to explore the dynamics of ending all use of one or more poliovirus vaccines to simplify the polio eradication endgame.

RESEARCH DESIGN AND METHODS

: With global reported cases of poliomyelitis trending higher since 2016, we apply an integrated global model to simulate prospective vaccine policies and strategies for OPV-using countries starting with initial conditions that correspond to the epidemiological poliovirus transmission situation at the beginning of 2022.

RESULTS

: Abruptly ending all OPV use in 2023 and relying only on IPV to prevent paralysis with current routine immunization coverage would lead to expected reestablished endemic transmission of poliovirus types 1 and 2, and approximately 150,000 expected cases of poliomyelitis per year. Alternatively, if OPV-using countries restart trivalent OPV (tOPV) use for all immunization activities and end IPV use, the model shows the lowest anticipated annual polio cases and lowest costs.

CONCLUSIONS

: Poor global risk management and coordination of OPV cessation remain a critical failure mode for the polio endgame, and national and global decision makers face difficult choices due to multiple available polio vaccine options and immunization strategies.

Collaboration-competition dilemma in flattening the COVID-19 curve

Testing for COVID-19 is a key intervention that supports tracking and isolation to prevent further infections. However, diagnostic tests are a scarce and finite resource, so abundance in one country can quickly lead to shortages in others, creating a competitive landscape. Countries experience peaks in infections at different times, meaning that the need for diagnostic tests also peaks at different moments. This phase lag implies opportunities for a more collaborative approach, although countries might also worry about the risks of future shortages if they help others by reallocating their excess inventory of diagnostic tests. This article features a simulation model that connects three subsystems: COVID-19 transmission, the diagnostic test supply chain, and public policy interventions aimed at flattening the infection curve. This integrated system approach clarifies that, for public policies, there is a time to be risk-averse and a time for risk-taking, reflecting the different phases of the pandemic (contagion vs. recovery) and the dominant dynamic behavior that occurs in these phases (reinforcing vs. balancing). In the contagion phase, policymakers cannot afford to reject extra diagnostic tests and should take what they can get, in line with a competitive mindset. In the recovery phase, policymakers can afford to give away excess inventory to other countries in need (one-sided collaboration). When a country switches between taking and giving, in a form of two-sided collaboration, it can flatten the curve, not only for itself but also for others.

Polio health economics: assessing the benefits and costs of polio, non-polio, and integrated activities of the Global Polio Eradication Initiative

Background: Investments made by countries and donors to support polio eradication and the Global Polio Eradication Initiative (GPEI) over the past 35 years provided financial support for significant health interventions beyond the prevention of polio. Prior economic analyses that sought to quantify the economic benefits of some interventions encountered insufficient data and evidence associated with non-polio-specific activities. The 2022-2026 GPEI Strategic Plan explicitly identified integration and gender equity as funded mandates that must move forward in parallel with polio eradication, but these goals remain vaguely defined from a health economic perspective. Methods: To ensure unambiguous and full accounting for all financial investments in the GPEI, polio eradication, and other desirable objectives, we identify the health economic analysis methods and inputs needed to ensure transparent financial accountability and cost-effective use of funds. Results: Sufficient inputs and methods exist to characterize the health and economic benefits of polio-specific activities, but we identified the need for additional information and method development for some non-polio-specific and cost-sharing activities. Donors who seek to support non-polio-specific objectives as part of the GPEI may want to provide dedicated support financing for which it may be difficult to apply typical health economic criteria and to expect net health and/or net economic benefits. Conclusions: Given the mixture of funding sources provided to the GPEI, which includes support by governments and private donors, we recommend that the GPEI separately account for financial needs that represent necessities for polio eradication from those used for other stated objectives. An added layer of specificity that identifies all funds according to each activity, the accountable party and/or parties, and the associated measurable health or other outcome(s), will enable improved health economic analyses and reporting to donors who seek to track returns on their investments.

Public preferences and willingness to accept a hypothetical vaccine to prevent a pandemic in Japan: a conjoint analysis

OBJECTIVES

Understanding public vaccine acceptability is critical to preparing for future pandemics. This research investigated Japanese individuals' willingness to be vaccinated against a hypothetical infectious disease.

METHODS

A conjoint analysis was conducted with a general public panel via an Internet survey agency. Vaccine efficacy, vaccine safety, duration of immunity, and price were chosen as analysis attributes. Each respondent chose from 12 hypothetical scenarios using an online panel.

RESULTS

From the 2,155 complete responses, 51,720 results were extracted and analyzed. Higher efficacy, lifetime immunity duration, and fear of the pandemic positively affected willingness to be vaccinated, while higher vaccination price and higher toxicity had negative effects. The number of infected individuals and deaths had no significant impact. A total of 69.2% of the study population reported being willing to receive a vaccine with 100% efficacy, lifetime immunity, and low toxicity and free of charge.

CONCLUSIONS

This study assessed the preferences for vaccines against infectious diseases with the potential to become pandemics during the COVID-19 pandemic in Japan. This result can influence vaccine-related policy and pandemic preparedness and help governments consider public intention to prepare health communication campaigns that encourage vaccination.

Health economic analyses of secondary vaccine effects: a systematic review and policy insights

INTRODUCTION

: Numerous analyses demonstrate substantial health economic impacts of primary vaccine effects (preventing or mitigating clinical manifestations of the diseases they target), but vaccines may also be associated with secondary effects, previously known as non-specific, heterologous, or off-target effects.

AREAS COVERED

: We define key concepts to distinguish primary and secondary vaccine effects for health economic analyses, summarized terminology used in different fields, and perform a systematic review of health economic analyses focused on secondary vaccine effects (SVEs).

EXPERT OPINION

: Health economists integrate evidence from multiple fields, which often use incomplete or inconsistent definitions. Like regulators and policy makers, health economists require high-quality evidence of specific effects. Consistent with the limited evidence on mechanisms of action for SVEs, the associated health economic literature remains highly limited, with 4 studies identified by our systematic review. The lack of specific and well-controlled evidence that supports quantification of specific SVEs limits the consideration of these effects in vaccine research, development, regulatory, and recommendation decisions and health economic analyses.

Hypothetical emergence of poliovirus in 2020: part 2. exploration of the potential role of vaccines in control and eradication

OBJECTIVES

The emergence of human pathogens with pandemic potential motivates rapid vaccine development. We explore the role of vaccines in control and eradication of a novel emerging pathogen.

METHODS

We hypothetically simulate emergence of a novel wild poliovirus (nWPV) in 2020 assuming an immunologically naïve population. Assuming different nonpharmaceutical interventions (NPIs), we explore the impacts of vaccines resembling serotype-specific oral poliovirus vaccine (OPV), novel OPV (nOPV), or inactivated poliovirus vaccine (IPV).

RESULTS

Vaccines most effectively change the trajectory of an emerging disease when disseminated early, rapidly, and widely in the background of ongoing strict NPIs, unless the NPIs successfully eradicate the emerging pathogen before it establishes endemic transmission. Without strict NPIs, vaccines primarily reduce the burden of disease in the remaining susceptible individuals and in new birth cohorts. Live virus vaccines that effectively compete with the nWPVs can reduce disease burdens more than other vaccines. When relaxation of existing NPIs occurs at the time of vaccine introduction, nWPV transmission can counterintuitively increase in the short term.

CONCLUSIONS

Vaccines can increase the probability of disease eradication in the context of strict NPIs. However, successful eradication will depend on specific immunization strategies used and a global commitment to eradication.

The impact of disruptions caused by the COVID-19 pandemic on global polio eradication

In early 2020, the COVID-19 pandemic led to substantial disruptions in global activities. The disruptions also included intentional and unintentional reductions in health services, including immunization campaigns against the transmission of wild poliovirus (WPV) and persistent serotype 2 circulating vaccine-derived poliovirus (cVDPV2). Building on a recently updated global poliovirus transmission and Sabin-strain oral poliovirus vaccine (OPV) evolution model, we explored the implications of immunization disruption and restrictions of human interactions (i.e., population mixing) on the expected incidence of polio and on the resulting challenges faced by the Global Polio Eradication Initiative (GPEI). We demonstrate that with some resumption of activities in the fall of 2020 to respond to cVDPV2 outbreaks and full resumption on January 1, 2021 of all polio immunization activities to pre-COVID-19 levels, the GPEI could largely mitigate the impact of COVID-19 to the delays incurred. The relative importance of reduced mixing (leading to potentially decreased incidence) and reduced immunization (leading to potentially increased expected incidence) depends on the timing of the effects. Following resumption of immunization activities, the GPEI will likely face similar barriers to eradication of WPV and elimination of cVDPV2 as before COVID-19. The disruptions from the COVID-19 pandemic may further delay polio eradication due to indirect effects on vaccine and financial resources.