
“We don't know why COVID-19 is so contagious, so that's a big problem.”
Zhong Nanshan (2020) cited in " Exclusive: Coronavirus outbreak may be over in China by April - expert https://www.reuters.com/article/us-china-health-doctor-exclusive/exclusive-chinas-top-virus-expert-says-outbreak-may-peak-this-month-idUSKBN2050VF" on Reuters, 11 February 2020.