In discussing the experience of dealing with the more infectious Delta variant of the coronavirus, China's top epidemiologist Zhong Nanshan noted that expanding the scope of the search for "close contacts" and conducting surveillance of animals in closed-off areas, among other measures, are effective in curbing the infection.
The highly contagious Delta variant forced South China's Guangdong Province, the first Chinese province to deal with it, to change its definition of "close contacts" and come up with new strategies to cope with the variant, according to Zhong.
The new definition of close contact was expanded to those who were in the same building as the patient or in the same workplace for the four days before the patient showed the onset of symptoms, Zhong said.
Zhong said that researchers also collected the nucleic acid samples of animals, such as rats, in closed and controlled areas, to exclude the possibility of the virus being transmitted by animals through excreta.
According to the epidemiologist, the new variant is not only more contagious than previous ones, but also has a shorter incubation period and longer time to turn negative in testing.
The incubation period of the Delta variant is one to three days, while the average incubation period of the COVID-19 virus in last year's surge in Wuhan was three to seven days, Zhong said.
People infected with the Delta strain in Guangzhou took 13 to 15 days to test negative, much longer than the common strain of seven to nine days, Zhong pointed out.
