BackgroundThe purpose of this study was to prospectively investigate the incidence of influenza-associated pulmonary aspergillosis (IAPA) in influenza patients admitted to intensive care units in Sweden.MethodsThe study included consecutive adult patients with PCR-verified influenza A or B in 12 Swedish intensive care units (ICUs) over four influenza seasons (2019-2023). Patients were screened using serum galactomannan and beta-d-glucan tests and fungal culture of a respiratory sample at inclusion and weekly during the ICU stay. Bronchoalveolar lavage was performed if clinically feasible. IAPA was classified according to recently proposed case definitions.ResultsThe cohort included 55 patients; 42% were female, and the median age was 59 (IQR 48-71) years. All patients had at least one galactomannan test, beta-d-glucan test and respiratory culture performed. Bronchoalveolar lavage was performed in 24 (44%) of the patients. Five (9%, 95% CI 3.8% - 20.4%) patients were classified as probable IAPA, of which four lacked classical risk factors. The overall ICU mortality was significantly higher among IAPA patients than non-IAPA patients (60% vs 8%, p = 0.01).ConclusionsThe study represents the first prospective investigation of IAPA incidence. The 9% incidence of IAPA confirms the increased risk of invasive pulmonary aspergillosis among influenza patients admitted to the ICU. Therefore, it appears reasonable to implement a screening protocol for the early diagnosis and treatment of IAPA in influenza patients receiving intensive care.Trial registrationClinicalTrials.gov NCT04172610, registered November 21, 2019