在荟萃分析中，研究人员发现痰液比鼻咽拭子或口咽拭子更准确。这项研究还表明早期检测可以提高COVID-19的诊断率。

Sputum testing provides higher rate of COVID-19 detection

https://www.sciencedaily.com/releases/2020/07/200724141023.htm

Abbas Mohammadi, Elmira Esmaeilzadeh, Yijia Li, Ronald J. Bosch, Jonathan Z. Li. SARS-CoV-2 detection in different respiratory sites: A systematic review and meta-analysis. EBioMedicine, 2020; 102903 DOI: 10.1016/j.ebiom.2020.102903