empty street São Paulo
© miguel schincariol/Agence France-Presse/Getty Images
An empty street amid Covid-19 restrictions in São Paulo, March 6.
Texas Gov. Greg Abbott announced last week that his state is ending its mask mandate and business capacity limits. While Democrats and many public-health officials denounced the move, ample data now exist to demonstrate that the benefits of stringent measures aren't worth the costs.

This wasn't always the case. A year ago I publicly advocated lockdowns because they seemed prudent given how little was known at the time about the virus and its effects. But locking society down has become the default option of governments all over the world, regardless of cost.

More than a year after the pandemic began, vaccination is under way in both Europe and the U.S. Yet stringent restrictions are still in place on both sides of the Atlantic. Germany, Ireland and the U.K. are still in lockdown, while France is two months into a 6 p.m. curfew that the French government says will last for at least four more weeks. In many U.S. states, in-person schooling is still rare.

This time last year we had no idea how difficult it would be to control the virus. Given how fast it had been spreading, people made the reasonable assumption that most of the population would be infected in a few weeks unless we somehow reduced transmission. Projections by the Imperial College Covid-19 Response Team in London projected that more than two million Americans could die in a few months. A lockdown would cut transmission, and while it couldn't prevent all infections, it would keep hospitals from being overwhelmed. It would "flatten the curve."

We have since learned that the virus never spreads exponentially for very long, even without stringent restrictions. The epidemic always recedes well before herd immunity has been reached. As I argue in a report for the Center for the Study of Partisanship and Ideology, people get scared and change their behavior as hospitalizations and deaths increase. This, in turn, reduces transmission.

I've looked at more than 100 regions and countries. None have seen exponential growth of the pandemic continue until herd immunity was reached, regardless of whether a government lockdown or other stringent measure was imposed. People eventually revert to more-relaxed behavior. When they do, the virus starts spreading again. That's why we see the "inverted U-shape" of cases and deaths everywhere.

Sweden was the first to learn this lesson, but many other countries have confirmed it. Initially held up as a disaster by many in the pro-lockdown crowd, Sweden has ended up with a per capita death rate indistinguishable from that of the European Union. In the U.S., Georgia's hands-off policies were once called an "experiment in human sacrifice" by the Atlantic. But like Sweden, Georgia today has a per capita death rate that is effectively the same as the rest of the country.

That isn't to say that restrictions have no effect. Had Sweden adopted more-stringent restrictions, it's likely the epidemic would have started receding a bit earlier and incidence would have fallen a bit faster. But policy may not matter as much as people assumed it did. Lockdowns can destroy the economy, but it's starting to look as if they have minimal effect on the spread of Covid-19.

After a year of observation and data collection, the case for lockdowns has grown much weaker. Nobody denies overwhelmed hospitals are bad, but so is depriving people of a normal life, including kids who can't attend school or socialize during precious years of their lives. Since everyone hasn't been vaccinated, many wouldn't yet be living normally even without restrictions. But government mandates can make things worse by taking away people's ability to socialize and make a living.

The coronavirus lockdowns constitute the most extensive attacks on individual freedom in the West since World War II. Yet not a single government has published a cost-benefit analysis to justify lockdown policies — something policy makers are often required to do while making far less consequential decisions. If my arguments are wrong and lockdown policies are cost-effective, a government document should be able to demonstrate that. No government has produced such a document, perhaps because officials know what it would show.

Mr. Lemoine is a doctoral candidate in philosophy at Cornell University and a fellow at the Center for the Study of Partisanship and Ideology.