J Breath Res. 2021 May 21. doi: 10.1088/1752-7163/ac0414. Online ahead of print.
BACKGROUND: Current diagnostic testing for coronavirus disease 2019 (COVID-19) is based on detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in nasopharyngeal swab samples by reverse transcription polymerase chain reaction (RT-PCR). However, this test is associated with increased risks of viral dissemination and environmental contamination and shows relatively low sensitivity, attributable to technical deficiencies in the sampling method. Given that COVID-19 is transmitted via exhaled aerosols and droplets, and that exhaled breath condensate (EBC) is an established modality for sampling exhaled aerosols, detection of SARS-CoV-2 in EBC offers a promising diagnostic approach. However, current knowledge on the detection and load of the virus in EBC collected from COVID-19 patients remains limited and inconsistent. The objective of the study was to quantify the viral load in EBC collected from COVID-19 patients and to validate the feasibility of SARS-CoV-2 detection from EBC as a diagnostic test for the infection.
METHOD: EBC samples were collected from 48 COVID-19 patients using a collection device, and viral loads were quantified by RT-PCR targeting the E gene. Changes in detection rates and viral loads relative to patient characteristics and days since disease onset were statistically evaluated.
RESULTS: Need for mechanical ventilation was significantly associated with higher viral load (p<0.05). Need for oxygen administration or mechanical ventilation, less than 3 days since onset, and presence of cough or fever were significantly associated with higher detection rates (p<0.05). Among spontaneously breathing patients, viral load in EBC attenuated exponentially over time. The detection rate was 86% at 2 days since onset and deteriorated thereafter. In mechanically ventilated patients, detection rate and viral load were high regardless of days since onset.
CONCLUSION: These results support the feasibility of using RT-PCR to detect SARS-CoV-2 from EBC for COVID-19 patients within 2 days of symptom onset.