Shutdown orders prevented about 60 million novel coronavirus infections in the United States and 285 million in China, according to a research study published Monday that examined how stay-at-home orders and other restrictions limited the spread of the contagion.
A separate study from epidemiologists at Imperial College London estimated the shutdowns saved about 3.1 million lives in 11 European countries, including 500,000 in the United Kingdom, and dropped infection rates by an average of 82 percent, sufficient to drive the contagion well below epidemic levels.
The two reports, published Monday in the journal Nature, provide fresh evidence that aggressive and unprecedented shutdowns, which caused massive economic disruptions and job losses, were necessary to halt the exponential spread of the novel coronavirus.
But the overwhelming majority of people remain susceptible to the virus. Only about 3 percent to 4 percent of people in the countries being studied have been infected to date, said Samir Bhatt, senior author of the Imperial College London study.
“This is just the beginning of the epidemic: we’re very far from herd immunity,” Bhatt said Monday in an email. “The risk of a second wave happening if all interventions and precautions are abandoned is very real.”
The first study, from researchers at the University of California at Berkeley, examined six countries — China, the United States, France, Italy, Iran and South Korea — and estimated how 1,717 interventions, such as stay-at-home orders, business closings and travel bans, altered the spread of the virus. The report concluded that those six countries collectively managed to avert 62 million test-confirmed infections. Because most people who are infected never get tested, the actual number of infections that were averted is much higher — about 530 million in the six countries, the Berkeley researchers estimated.
Timing is crucial, the study found. Small delays in implementing shutdowns can lead to “dramatically different health outcomes.” The report, while reviewing what worked and what made little difference, is clearly aimed at the many countries around the planet that are still early in their battle against the coronavirus.
“Societies around the world are weighing whether the health benefits of anti-contagion policies are worth their social and economic costs,” the Berkeley team wrote. The economic costs of shutdowns are highly visible — closed stores, huge job losses, empty streets, food lines. The health benefits of the shutdowns, however, are invisible, because they involve people not sickened.
That spurred the researchers to come up with their estimates of infections prevented. The Berkeley team did not produce an estimate of lives saved.
One striking finding: School closures seemed to have no significant effect, although the authors said the issue requires further study. Banning large gatherings had more of an effect in Iran and Italy than in the other countries.
This is a developing story. It will be updated.