5. Sputum collection
Sputum collection may be performed during voluntary coughing or involuntary induction. To et al performed sputum collection by having patients cough into a sterile container, and demonstrated consistent detection of viral RNA levels in collected specimens.15 In another limited study of ten COVID-19 patients, Lo et al reported that SARS-CoV-2 RNA was detected in 90% of nasopharyngeal swab specimens but falsely absent in 10% (one patient).16 This patient was ultimately diagnosed after viral detection in collected sputum after one negative and one inconclusive result from nasopharyngeal swabs (inconclusive result was defined as a Ct-value of 36 to 38). The superiority of sputum for SARS-CoV-2 viral detection was also echoed by Pan et al, who demonstrated that sputum samples generally showed higher viral loads than throat swabs.17