People who didn’t know they had COVID-19 drove its spread in China
Mild cases of COVID-19 that go unrecognized are fueling the coronavirus pandemic, a new study of the early days of the outbreak in China suggests. It’s this stealth transmission from undetected cases that U.S. officials are now scrambling to limit with a slew of recently announced social distancing measures (SN: 3/13/20). On March 16, the White House coronavirus task force advised people to avoid gatherings of more than 10 people for the next 15 days. States including Pennsylvania, Ohio and New York, as well as Washington, D.C., have shut down bars and restaurants. And on March 17, a shelter-in-place order affecting close to 7 million people in the San Francisco Bay area went into effect. Similar efforts have been taken around the globe. In the new study, researchers used data on people’s movement in China from January 10 to January 23 to simulate how SARS-CoV-2, the virus that causes COVID-19, spread before restrictions on travel within the country and other isolation measures were implemented....