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Grass D, Wrzaczek S, Caulkins JP, Feichtinger G, Hartl RF, Kort PM, Kuhn M, Prskawetz A, Sanchez-Romero M, Seidl A. Riding the waves from epidemic to endemic: Viral mutations, immunological change and policy responses. Theor Popul Biol 2024; 156:46-65. [PMID: 38310975 DOI: 10.1016/j.tpb.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/06/2024]
Abstract
Nonpharmaceutical interventions (NPI) are an important tool for countering pandemics such as COVID-19. Some are cheap; others disrupt economic, educational, and social activity. The latter force governments to balance the health benefits of reduced infection and death against broader lockdown-induced societal costs. A literature has developed modeling how to optimally adjust lockdown intensity as an epidemic evolves. This paper extends that literature by augmenting the classic SIR model with additional states and flows capturing decay over time in vaccine-conferred immunity, the possibility that mutations create variants that erode immunity, and that protection against infection erodes faster than protecting against severe illness. As in past models, we find that small changes in parameter values can tip the optimal response between very different solutions, but the extensions considered here create new types of solutions. In some instances, it can be optimal to incur perpetual epidemic waves even if the uncontrolled infection prevalence would settle down to a stable intermediate level.
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Affiliation(s)
- D Grass
- International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria; Research Group Economics, Institute of Statistics and Mathematical Methods in Economics, TU Wien, Vienna, Austria
| | - S Wrzaczek
- International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria; Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria.
| | - J P Caulkins
- Heinz College, Carnegie Mellon University, Pittsburgh, USA
| | - G Feichtinger
- Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria; Research Group Variational Analysis, Dynamics & Operations Research, Institute of Statistics and Mathematical Methods in Economics, TU Wien, Vienna, Austria
| | - R F Hartl
- Department of Business Decisions and Analytics, University of Vienna, Vienna, Austria
| | - P M Kort
- Tilburg School of Economics and Management, Tilburg University, Tilburg, Netherlands
| | - M Kuhn
- International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria; Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria
| | - A Prskawetz
- International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria; Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria; Research Group Economics, Institute of Statistics and Mathematical Methods in Economics, TU Wien, Vienna, Austria
| | - M Sanchez-Romero
- International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria; Research Group Economics, Institute of Statistics and Mathematical Methods in Economics, TU Wien, Vienna, Austria; Vienna Institute of Demography (VID), Austrian Academy of Sciences (OeAW), Vienna, Austria
| | - A Seidl
- Department of Business Decisions and Analytics, University of Vienna, Vienna, Austria; Faculty of Management, Seeburg Castle University, Seekirchen am Wallersee, Austria
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Caulkins JP, Grass D, Feichtinger G, Hartl RF, Kort PM, Kuhn M, Prskawetz A, Sanchez-Romero M, Seidl A, Wrzaczek S. The hammer and the jab: Are COVID-19 lockdowns and vaccinations complements or substitutes? EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2023; 311:233-250. [PMID: 37342758 PMCID: PMC10131897 DOI: 10.1016/j.ejor.2023.04.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 04/19/2023] [Indexed: 06/23/2023]
Abstract
The COVID-19 pandemic has devastated lives and economies around the world. Initially a primary response was locking down parts of the economy to reduce social interactions and, hence, the virus' spread. After vaccines have been developed and produced in sufficient quantity, they can largely replace broad lock downs. This paper explores how lockdown policies should be varied during the year or so gap between when a vaccine is approved and when all who wish have been vaccinated. Are vaccines and lockdowns substitutes during that crucial time, in the sense that lockdowns should be reduced as vaccination rates rise? Or might they be complementary with the prospect of imminent vaccination increasing the value of stricter lockdowns, since hospitalization and death averted then may be permanently prevented, not just delayed? We investigate this question with a simple dynamic optimization model that captures both epidemiological and economic considerations. In this model, increasing the rate of vaccine deployment may increase or reduce the optimal total lockdown intensity and duration, depending on the values of other model parameters. That vaccines and lockdowns can act as either substitutes or complements even in a relatively simple model casts doubt on whether in more complicated models or the real world one should expect them to always be just one or the other. Within our model, for parameter values reflecting conditions in developed countries, the typical finding is to ease lockdown intensity gradually after substantial shares of the population have been vaccinated, but other strategies can be optimal for other parameter values. Reserving vaccines for those who have not yet been infected barely outperforms simpler strategies that ignore prior infection status. For certain parameter combinations, there are instances in which two quite different policies can perform equally well, and sometimes very small increases in vaccine capacity can tip the optimal solution to one that involves much longer and more intense lockdowns.
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Affiliation(s)
- J P Caulkins
- Heinz College, Carnegie Mellon University, Pittsburgh, USA
| | - D Grass
- International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg 2361, Austria
| | - G Feichtinger
- Department for Operations Research and Control Systems, Institute of Statistics and Mathematical Methods in Economics, Vienna University of Technology, Vienna, Austria
| | - R F Hartl
- Department of Business Decisions and Analytics, University of Vienna, Vienna, Austria
| | - P M Kort
- Tilburg School of Economics and Management, Tilburg University, Tilburg, Netherlands
| | - M Kuhn
- International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg 2361, Austria
- Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria
| | - A Prskawetz
- International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg 2361, Austria
- Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria
- Research Group Economics, Institute of Statistics and Mathematical Methods in Economics, Vienna University of Technology, Vienna, Austria
| | - M Sanchez-Romero
- International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg 2361, Austria
- Research Group Economics, Institute of Statistics and Mathematical Methods in Economics, Vienna University of Technology, Vienna, Austria
| | - A Seidl
- Department of Business Decisions and Analytics, University of Vienna, Vienna, Austria
| | - S Wrzaczek
- International Institute for Applied Systems Analysis (IIASA), Schlossplatz 1, Laxenburg 2361, Austria
- Wittgenstein Centre for Demography and Global Human Capital (IIASA, VID/OeAW, University of Vienna), Austria
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Walkowiak MP, Walkowiak D, Walkowiak J. To vaccinate or to isolate? Establishing which intervention leads to measurable mortality reduction during the COVID-19 Delta wave in Poland. Front Public Health 2023; 11:1221964. [PMID: 37744498 PMCID: PMC10513426 DOI: 10.3389/fpubh.2023.1221964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 08/21/2023] [Indexed: 09/26/2023] Open
Abstract
Background During the Delta variant COVID-19 wave in Poland there were serious regional differences in vaccination rates and discrepancies in the enforcement of pandemic preventive measures, which allowed us to assess the relative effectiveness of the policies implemented. Methods Creating a model that would predict mortality based on vaccination rates among the most vulnerable groups and the timing of the wave peak enabled us to calculate to what extent flattening the curve reduced mortality. Subsequently, a model was created to assess which preventive measures delayed the peak of infection waves. Combining those two models allowed us to estimate the relative effectiveness of those measures. Results Flattening the infection curve worked: according to our model, each week of postponing the peak of the wave reduced excess deaths by 1.79%. Saving a single life during the Delta wave required one of the following: either the vaccination of 57 high-risk people, or 1,258 low-risk people to build herd immunity, or the isolation of 334 infected individuals for a cumulative period of 10.1 years, or finally quarantining 782 contacts for a cumulative period of 19.3 years. Conclusions Except for the most disciplined societies, vaccination of high-risk individuals followed by vaccinating low-risk groups should have been the top priority instead of relying on isolation and quarantine measures which can incur disproportionately higher social costs. Our study demonstrates that even in a country with uniform policies, implementation outcomes varied, highlighting the importance of fine-tuning policies to regional specificity.
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Affiliation(s)
- Marcin Piotr Walkowiak
- Department of Preventive Medicine, Poznan University of Medical Sciences, Poznań, Poland
| | - Dariusz Walkowiak
- Department of Organization and Management in Health Care, Poznan University of Medical Sciences, Poznań, Poland
| | - Jarosław Walkowiak
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznań, Poland
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