Are two consecutive negative RT-PCRs enough to rule out COVID-19?

Waked, Rami; Makhoul, Jennifer; Saliba, Gebrael; Chehata, Nabil; Mortada, Sadek; Zoghbi, Antoine; Choucair, Jacques; Haddad, Elie

The COVID-19 pandemic is redefining the world we live in, and scientists are struggling to find an optimal SARS-CoV-2 diagnostic tool. Routine testing is currently performed using real time reverse transcription polymerase chain reaction (RT-PCR) of upper or lower respiratory tract secretions. The objective of this article is to demonstrate the importance of conducting RT-PCRs using deep sampling when initial upper respiratory testing is negative, in cases of high index of suspicion for COVID-19. We present the case of a 47-year-old man admitted for fever and bilateral pneumonia on chest CT scan, amid the early peak of the COVID-19 pandemic, suggesting a SARS-CoV-2 infection. RT-PCR results done twice using nasopharyngeal swabs were negative. A bronchoscopy was then performed, and RT-PCR testing on bronchoalveolar lavage yielded positive results, confirming the diagnosis of COVID-19 pneumonia. In conclusion, RT-PCR samples of the lower respiratory tract likely contain a higher viral load and thus retain a higher sensitivity for SARS-CoV-2 detection.