When Chinese officials in the city of Wuhan discovered a cluster of just six COVID-19 cases about two weeks ago — the first cases there in more than a month — they quickly drafted an ambitious plan to cover the entire city of about 11 million people. test and destroy a possible second wave of infection. And they initially planned to do it in just 10 days.
Ten days out, they had almost reached that goal. According to state media, the Wuhan Municipal Health Commission collected more than 9 million residents between May 15 and May 24 and tested more than 6.5 million of those smears for coronavirus genetic material.
Labs in the city went from performing 46,000 tests a day to a whopping 1.47 million in the screening print, according to The New York Times. The Times notes that New York has tested 1.7 million people in the US since March 4, a span of nearly three months, according to The Atlantic’s COVID Tracking Project.
Wuhan officials conducted the mass screening in a staggered neighborhood-by-neighborhood sweep. They then accelerated swab processing by conducting batches of testing. That is, they combined material from five to 10 swabs and tested the pooled sample in one go. If any of the pooled swabs tested positive for the novel coronavirus, SARS-CoV-2, officials could go back to that handful of people and test them again. This type of batch testing works well for moving quickly through a population when cases are rare.
So far, the testing campaign has identified 218 asymptomatic cases, Wuhan officials reported. Those cases are now in quarantine.
With most of the testing now complete, city officials are working to “check the leaks and fill the gaps” to make sure no residents are missed.
Some residents have told the Times they opposed the testing campaign because it forced them to have more contact with others, potentially putting them at risk of infection. However, others argued that the testing provided psychological benefits as people returned to work.
“This push to test everyone would improve the vitality of the city and provide a scientific basis for the resumption of work,” Yang Zhanqiu, a virologist at Wuhan University, told the Times. “It can also put people at ease and give everyone some peace of mind.”