Nucleic acid tests work by detecting the genetic code of the virus and may be more effective in detecting infection, particularly in the early stages, than tests that examine a body’s immune response, although these are easier to conduct.
Mass tests identified 198 asymptomatic cases – people who carry the virus but show no symptoms, according to the state-run Health Times.
The speed and scale of Wuhan’s test campaign – hailed as a “10-day battle” by local authorities – appears to have matched or eclipsed the testing capacity of many countries, including that of the United States.
On Friday alone, Wuhan conducted 1.47 million tests, according to CCTV.
In total, the United States has performed 14,131,277 coronavirus tests since the start of the pandemic, according to the latest data from the U.S. Centers for Disease Control and Prevention. However, that number also includes antibody tests performed in some states, which are not used to diagnose current infections but to indicate whether someone has been exposed to the virus in the past.
In Wuhan, sampling booths have been set up in neighborhoods across the city, with residents in face masks lining up to take swab tests. On Saturday, authorities set up 231 extra test booths for people who had not been able to carry out the previous tests, according to the Changjiang Daily, the official Communist Party spokesman in Wuhan.
Health workers also carried out door-to-door visits to some elderly and disabled residents to collect their samples, according to the Changjiang newspaper.
According to the Chinese news point Caixin, in order to quickly and extensively test, the Wuhan health authorities have combined some of the samples taken from multiple individuals together and tested them in a single test tube, a method known as “pool testing”.
If a test tube of pooled specimens tested positive, further tests would be performed on each individual’s sample separately to find the positive sample, says the Caixin report. It was not clear from the report what percentage of samples in Wuhan had been collected for testing.
CNN contacted the Wuhan Health Commission for comment on joint sampling procedures, but received no response.