Sampling from upper and/or lower respiratory tract when diagnosing coronavirus disease 2019 (COVID-19) - results from a Danish cohort study.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can replicate in the upper and lower respiratory tract. We aimed to evaluate whether symptom characteristics and symptom duration prior to sampling are associated with test positivity in upper or lower respiratory tract samples.

Methods: We conducted a retrospective cohort study in the Central Denmark Region from 14 April 2020 to 2 November 2020 including hospitalised patients with SARS-CoV-2 reverse transcriptase-polymerase chain reaction samples from both the upper and lower respiratory tract within 48 h and at least one positive test result.