Coronavirus: Lockdowns prevented the worst, researchers say | Science| In-depth reporting on science and technology | DW | 16.06.2020
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Coronavirus: Lockdowns prevented the worst, researchers say

Two studies show that anti-COVID-19 measures taken by many governments were sensible and effective. Without restrictions on the freedom of movement of their citizens, hundreds of millions more would have fallen ill.

COVID-19: Leere Straßen in London

No pedestrians, no cars: The empty Westminster-Bridge in London

Researchers from the University of California/Berkeley  (UC Berkeley) and Imperial College London  last week published studies in the scientific journal Nature looking into the question of how badly the coronavirus pandemic would have developed if governments had not adopted lockdown measures and social distancing rules.

Solomon Hsiang's team from the Global Policy Laboratory  at UC Berkeley examined the situation in six major countries: China, South Korea, Italy, France, Iran and the United States. The conclusion: The emergency measures in all these countries had "significantly and substantially slowed" the pandemic.

530 million infections prevented 

In the peer-reviewed study,  the authors write that travel restrictions, company and school closures, curfews and other "non-pharmaceutical interventions," such as masks and distancing rules, averted about 530 million infections altogether in the six countries.

Infografik Covid pandemic projections EN

Of those infections, however, only 62 million would probably have been registered as confirmed cases because the countries concerned had limited testing capacities. The research team based its observations on a period up to April 6 and examined 1,717 individual political measures.

Hsiang emphasized how helpful the willingness of each individual to make sacrifices in the coronavirus crisis had been: "The last several months have been extraordinarily difficult, but through our individual sacrifices, people everywhere have each contributed to one of humanity's greatest collective achievements," Hsiang said. 

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Argentina's long lockdown

"I don't think any human endeavor has ever saved so many lives in such a short period of time. There have been huge personal costs to staying home and canceling events," the political scientist said. "But the data show that each day made a profound difference. By using science and cooperating, we changed the course of history."

The authors of the Berkeley study did not analyze how many lives were saved as a result of the preventive actions. This was because such an estimate would have been too uncertain given the dramatic increase in infection rates and the resulting probable overburdening of health care systems if the actions had not been taken.

3.1 million lives saved in 11 countries

The research team led by the epidemiologist Samir Bhatt of the Centre for the Analysis of Global Infectious Diseases  at Imperial College, on the other hand, did venture to undertake this tricky analysis. It examined 11 European countries, looking at the period up to May 4, 2020. This study,  whose central focus was on the development of the reproduction number R, also shows that lockdown measures effectively slowed the pandemic. 

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The researchers calculated that by May 4, between 12 and 15 million people had become infected with SARS-CoV-2. This corresponds to between 3.2% and 4% of the respective populations of the countries studied. According to their calculations, 3.1 million lives were saved through various protective measures. 

Caution advised — a second wave could be imminent

"Our model suggests that the measures put in place in these countries in March 2020 were successful in controlling the epidemic by driving down the reproduction number and significantly reducing the number of people who would have been infected by the virus SARS-CoV-2," says Seth Flaxman,  who accompanied the study on behalf of the Faculty of Mathematics.

His colleague Bhatt added that it would still be necessary in future to follow developments very closely to prevent a renewed increase in infections.

There were uncertainties in the research, Bhatt acknowledged. He said one limitation of the model was that it assumed that every measure had the same effect in all countries. In reality, however, there were great variations in how the lockdown was implemented in different countries. But this does not change the main message of the study, according to Bhatt. 

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