Economic Irreversibility: The Universal Guiding Principle of Infection Control
© The Physical Society of Japan
This article is on
J. Phys. Soc. Jpn.
90,
114007
(2021)
.
It is preferable to avoid lockdowns, as lockdowns at seriously spread phases are very expensive. It would be economically better to utilize less intense countermeasures as early as possible to avoid lockdowns in later phases.
Since the early 2020, governments across the globe have grappled with preventing the spread of COVID19 and mitigating the economic impacts of this deadly virus. Several debates have raged over the methods to balance stringent infection control while maintaining a sense of economic normalcy.
In this study, theories of thermodynamics have been used to generate a new concept termed as "economic irreversibility." It contends that delaying infection control measures is additionally expensive in the long run.
Although, certain economists have utilized a costbenefit analysis to argue for timely intervention, its universal applicability remains questionable. This is because previous studies have been performed using numerical simulations that include investigating specific situations with given parameters the results of which depend on the socioeconomic conditions and on the characteristics of the infectious agents.
To further develop a universal guiding principle to control pandemics, the author’s experience in thermodynamics is utilized.
A costbenefit analysis is an optimization problem similar to exploring more efficient thermal cycles in thermodynamics. The benefit and cost are the reduction in infections, and the economic damage caused by the countermeasure, respectively. The efficiency of the countermeasure processes are theoretically compared with the same period in which the initial and the final infection status (the number of infected persons) remain the same.
The application of economic irreversibility showed that the delay in infection control results in increased costs and contradicts the idea that infection control translates into economic damage. In terms of thermodynamics, it can be said that early countermeasures render the situation more reversible.
Furthermore, this study did not require adjusting for different infectious diseases or socioeconomic conditions, making it applicable on a wider scale. It can be applied to the current COVID19 pandemic or probable future ones, regardless of whether “herd immunity” exists or not. To the best of the author’s knowledge, this is the first analytical study of the economic efficiency during pandemic control.
The validity of the present study is subject to the assumptions of the methodology. In this study, two principal assumptions have been made:
1.  The intervention cost depends on the effective reproduction number, and its cost function is concave as to the effective reproduction number. 
2.  The epidemic is in the infectionspreading phase and thus the infected population increases and decreases while obeying exponential dynamics. 
It is assumed that countermeasures are utilized in order corresponding to their costeffectiveness. Moreover, exponential dynamics is a common feature of pandemics. Thus, the results are not restricted to a specific model; however, they demonstrate the basic underlying characteristics of pandemic countermeasures.
(Written by T. Hondou)
J. Phys. Soc. Jpn.
90,
114007
(2021)
.
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