很多COVID-19感染者实际上并没有症状 什么时候传(2)

[6] WHO. Transmission of SARS-CoV-2: implications for infection prevention precautions. Jul 9, 2020. Retrieved Aug 16, 2020 from https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions

[7] Quentin Fottrell. This is when people with COVID-19 are at their most contagious. Aug 16, 2020. Retrieved Aug 16, 2020 from https://www.marketwatch.com/story/covid-19-infections-just-hit-20-million-worldwide-why-the-actual-number-of-cases-is-likely-much-higher-2020-08-11

[8] CBS News. Gottlieb Says US Likely ‘A Long Way’ From Herd Immunity To Virus. Aug 16th, 2020. Retrieved Aug 17, 2020 from https://www.news9.com/story/5f39db685853700b8096e4f4/gottlieb-says-us-likely-a-long-way-from-herd-immunity-to-virus-