FIGURE 1.

A flow diagram summarising the participants who were enrolled between January 2021 and August 2023 and underwent bronchoscopy. 13 subjects were identified as having persistent respiratory symptoms ≥3 months post-COVID-19 (coronavirus disease 2019) infection and scored >10 in the St George's Respiratory Questionnaire (pulmonary long COVID). Nine subjects were selected as controls due to either no history of COVID-19 infection or lack of persistent respiratory symptoms post-infection. The final number of subjects used for analysis was nine in the pulmonary long COVID group and nine in the control group. ^#: subjects with pre-existing chronic respiratory disorders and participants who were heavily smoking tobacco cigarettes or using cannabis or e-cigarettes at the time of recruitment were excluded.