Study population and design
This was a pilot prospective observational cohort study at Washington University/ Barnes Jewish Hospital in St. Louis, MO between Aug 2020 and March 2021. This study was conducted according to the Declaration of Helsinki principles (as revised in 2013) and was approved by the Washington University Institutional Review Board (protocol # 202006151). Adult subjects with COVID-19 related pneumonia diagnosed by nasopharyngeal SARS-CoV-2 RT-PCR who required endotracheal intubation and mechanical ventilation for ARDS were considered for the study. Informed consent was obtained from the legally-authorized representative. ARDS was defined according to the Berlin criteria (9).
We collected demographic and clinical variables of interest from the electronic health records including age, gender, race, weight, body mass index, comorbidities, prior use of immunosuppressive medications, treatments administered, BAL and laboratory results and relevant outcomes (mortality, duration of ventilation and length of stay in the hospital). Subjects were enrolled if they had undergone bronchoscopy with BAL performed for clinical reasons, most commonly to rule out bacterial pneumonia. Immune response markers and cycle threshold (Ct) SARS-CoV-2 RT-PCR were obtained from the subjects’ plasma and BAL fluid. We excluded intubated subjects who did not undergo planned clinical bronchoscopy and those subjects who we could not obtain informed consent in sufficient time to analyze / store the fresh samples.