U.S. COVID-19 fatalities could have stayed under 300,000, versus a death toll of 540,000 and rising, if by last May the country had adopted widespread mask, social distancing, and testing protocols while awaiting a vaccine, estimated Andrew Atkeson, economics professor at University of California, Los Angeles.

He likened the state-by-state, patchwork response to a car’s cruise control. As the virus worsened people hunkered down, but when the situation improved restrictions were dropped and people were less careful, with the result that “the equilibrium level of daily deaths … remains in a relatively narrow band” until the vaccine arrived.

Atkeson projected a final fatality level of around 670,000 as vaccines spread and the crisis subsides. The outcome, had no vaccine been developed, would have been a far-worse 1.27 million, Atkeson estimated.