COVID-19 and optimal lockdown strategies: The effect of new and more virulent strains.

Abstract

Most nations have responded to the COVID-19 pandemic by locking downparts of their economies to reduce infectious spread. The optimal timing of thebeginning and end of the lockdown, together with its intensity, is determined by thetradeoff between economic losses and improved health outcomes. These choices can be modeled within the framework of an optimal control model that recognizes thenonlinear dynamics of epidemic spread and the increased risks when infection ratessurge beyond the healthcare system's capacity. Past work has shown that within sucha framework very different strategies may be optimal ranging from short to long andeven multiple lockdowns, and small changes in the valuation placed on preventing apremature death may lead to quite different strategies becoming optimal. There evenexist parameter constellations for which two or more very different strategies can beoptimal. Here we revisit those crucial questions with revised parameters reflectingthe greater infectivity of the recently detected "UK variant" of the SARS-CoV-2virus and describe how the new variant may affect levels of mortality and otheroutcomes.