because calcium alginate or wooden-shaft swabs might inactivate the virus and could provide a negative result for the nucleic-acid assay. After the collection of the swab, it should be placed immediately into a 2-3 mL of sterile medium or saline for proper viral transport. If the NP swabs are not available, then the anterior nares and mid-turbinate specimen can also be collected from the symptomatic patients for the detection of the viral infection.

**Oropharyngeal swabs:** Another important specimen recommended by the WHO and CDC to detect SARS-CoV-2 infection is the OP. This swab is collected from the posterior pharynx region, avoiding contact with the tongue. According to the CDC, if the NP and OP specimens are collected together, then both specimens should be placed in a single vial for more sensitive and appropriate results of the SARS-CoV-2 infection.

**Bronchoalveolar lavage and tracheal aspirate:** For patients who are severely ill or having severe symptoms for the COVID-19 disease, the bronchoalveolar lavage (BAL) and tracheal aspirate could be used from the lower respiratory tract. The BAL sample is acquired using a bronchoscope or catheter into the bronchus, where the aspirated fluid with the virus will be collected for the testing of the COVID-19 infection.

**Sputum:** The patients who have severe coughing symptoms will be asked to collect their sputum as the sample to detect the viral infection. The patients will be asked to rinse the mouth with sterile water and further expel the deep cough sputum straight away into a sterile, leak-proof, screw-cap-tightened sputum collection cup or sterile dry container.

**Other samples:** Since SARS-CoV-2 is present in blood and stool, these specimens can be collected in addition to the respiratory specimens. However, the efficacy of these tests remains unclear, because the data on viral shedding is still preliminary. In addition, for patients who have died, autopsy material and lung tissue may be used to test for the presence of the virus. Based on the sample