Individual Choices, Not Lockdowns. Most people don't ignore risks, and they can react more quickly than governments.

City Journal ^ | Summer 2021 | Joel Zinberg

[karpov]

After a year of start-and-stop public-health measures, more often guided by intuition than by science, studies are confirming what economists long suspected: the Covid-19 lockdowns were an expensive, unnecessary failure, based on models that overestimated the number of cases and deaths because they failed to account for individual responses to the pandemic.

Epidemiologists viewed lockdowns as the logical response to a new virus to which humans lacked immunity and that could overwhelm hospitals and cause many deaths. Yet health economists, following seminal work by Tomas Philipson, have long understood that people respond to incentives and alter their behaviors to avoid the risks and costs of infectious diseases. Epidemiologists failed to account for these voluntary changes in assessing what would happen without a lockdown.

The influential Imperial College of London model was typical. In March 2020, it predicted exponential growth of Covid cases that would overwhelm ICU bed capacity by early April and cause 2.2 million U.S. deaths by July. The authors recommended prolonged lockdowns until vaccines became available.

The model grossly overpredicted deaths because of critical errors, including an unrealistically high infection-fatality rate. Most important, its predictions were based on the “unlikely” scenario that there would be no changes in individual behaviors. The model used a reproduction number, or Rt—the average number of secondary infections that each infected person produces in a susceptible population—that was too high and, contrary to standard epidemiological practice, did not vary over time. In fact, Rt declines as people voluntarily avoid contact with others and as the number of recovered people no longer susceptible to infection grows.