Fungal infections of the lung during and after the COVID-19 pandemic: Retrospective observational comparison

The coronavirus disease (COVID-19) pandemic has been associated with an increased burden of secondary infections, including fungal infections of the lungs, especially in critically ill patients. However, it is unclear whether this excess risk persisted in the post-pandemic period after infection-control practices and clinical pathways were optimized. This single-center retrospective observational study included 1441 PCR positive COVID-19 patients hospitalized during the COVID-19 pandemic and after the pandemic. Microbiological investigations, fungal cultures, serum galactomannan antigen tests, and Pneumocystis jirovecii PCR tests were performed. The rates of positive test results for fungal infections were calculated as percentages and statistically compared between the 2 periods. Overall, 99 of 1441 patients (6.9%) had at least 1 positive fungal test. The study findings showed that the positive test results for fungal species declined after the pandemic, from 9.15% to 5.13% for all species, 17.36% to 9.29% for Candida species, and 2.22% to 1.00% for Aspergillus species. The decrease in the positive test result rates for all fungal and Candida species was statistically significant ( P = .003 and P = .002, respectively). An increased prevalence of pulmonary fungal infections was observed in patients hospitalized during the COVID-19 pandemic. The lower fungal positivity observed in the post-pandemic period may reflect changes in the patient case-mix, diagnostic intensity, and evolving clinical and infection-control practices; however, causal inferences cannot be made from this observational analysis. These findings may inform preparedness, infection-control, and stewardship strategies for preventing and managing pulmonary fungal co-infections during future respiratory virus outbreaks.