What we know about the Delta variant?

5. In what environments does the Delta variant spread?

Closed indoor environments are most conducive to transmission of the variant.

China's leading respiratory disease expert Zhong Nanshan said because of the high viral load of the Delta strain in carriers, masks should be worn in crowded or poorly ventilated places to prevent infection.

6. Do current vaccines protect against the Delta strain?

Preliminary research has shown Chinese vaccines are 100 percent effective in preventing serious COVID-19 symptoms from the Delta variant, 76.9 percent effective in preventing moderate symptoms, 67.2 percent effective against acquisition of mild symptoms and 63.2 percent effective in preventing a patient from becoming an asymptomatic carrier, according to Zhong Nanshan.

Hu Shuchen contributed to the story