1
|
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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
2
|
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? Eur J Oper Res 2023; 311:233-250. [PMID: 37342758 PMCID: PMC10131897 DOI: 10.1016/j.ejor.2023.04.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
4
|
Abstract
We developed a new TLD array for precise dose measurement and verification of the spatial dose distribution in small radiation targets. It consists of a hemicylindrical, tissue-equivalent rod made of polystyrene with 17 parallel moulds for an exact positioning of each TLD. The spatial resolution of the TLD array was evaluated using the Leskell spherical phantom. Dose planning was performed with KULA 4.4 under stereotactic conditions on axial CT images. In the Leksell gamma unit the TLD array was irradiated with a maximal dose of 10 Gy with an unplugged 14 mm collimator. The doses delivered to the TLDs were rechecked by diode detector and film dosimetry and compared to the computer-generated dose profile. We found excellent agreement of our measured values, even at the critical penumbra decline. For the 14 mm and 18 mm collimator and for the 11 mm collimator combination we compared the measured and calculated data at full width at half maximum. This TLD array may be useful for phantom or tissue model studies on the spatial dose distribution in confined radiation targets as used in stereotactic radiotherapy.
Collapse
Affiliation(s)
- A Ertl
- Department of Neurosurgery, University of Vienna, Austria
| | | | | | | | | |
Collapse
|