Viral infections of the respiratory tract can lead to chronic lung injury through immunopathological mechanisms that remain unclear. Communities of commensal bacteria colonising the respiratory tract, known as the respiratory tract microbiota, are altered in viral infections, which can contribute to inflammation, lung epithelial damage and subsequent development of lung disease. Emerging evidence on post-viral lung injury suggests an interplay between viral infections, immune responses and airway microbiota composition in the development of viral-induced lung diseases. In this review, we present the clinical characteristics of post-viral lung injury, along with the underlying immunopathological mechanisms and host–bacteria interactions, with a focus on influenza virus, respiratory syncytial virus and coronaviruses. Additionally, considering the important role of the airway microbiota in viral-induced pulmonary sequelae, we suggest key areas for future research on respiratory microbiota involvement in the development of post-viral lung diseases.

Rationale: Severe SARS-CoV-2 infection induces disrupted oropharyngeal and gut microbiota during acute disease which may persist and contribute to the development of post-acute pulmonary sequelae. To date, it is unclear whether dysbiosis following severe disease is linked to long-term pulmonary function impairment. Objectives: To determine associations between oropharyngeal and gut microbiota composition with lung function after severe COVID-19. Methods: 16S and internal transcribed spacer (ITS) rRNA amplicon sequencing were performed on oropharyngeal (16S and ITS) and rectal (16S) swabs at 3-, 6- and 12-months post-hospitalisation from 83 subjects previously admitted to the ICU with severe COVID-19 (Swiss COVIDlung study, NCT04581135 ). Subjects underwent 1-3 follow-up visits during which lung function testing was performed to investigate associations with microbiota composition. Measurements and Main Results: The oropharyngeal microbiota of subjects having suffered from COVID-19-related-severe acute non-cardiogenic hypoxemic respiratory failure with bilateral lung infiltrates (AHRF-BLI) was characterized by decreased α-diversity and the presence of differentially abundant taxa. Subjects who recovered in lung function (TLC, FVC, FEV ₁ and DLCO >Lower Limit of Normal) had a distinct oropharyngeal and gut microbiota composition compared to those whose lung function never recovered. Fungal analysis of oropharyngeal samples revealed the presence of three distinct clusters which were characterized by distinct lung-function associated bacterial-fungal co-occurrence. Conclusions: This study provide first insights into the role of the airway and gut microbiota in the development of long-term pulmonary sequelae after severe SARS-CoV-2 infection, shedding the light on the potential of the microbiota for preventive and therapeutic strategies in severe COVID-19.

Acute pulmonary embolism (PE) is a major cause of cardiovascular mortality, and managing patients at risk of deterioration despite anticoagulation is challenging. Transcatheter interventions, including catheter-directed thrombolysis (CDT) and mechanical thrombectomy (MT), aim to rapidly unload the right ventricle while limiting the bleeding risk of systemic thrombolysis. Their use long preceded robust evidence, but recent randomised trials have changed this. In normotensive patients with right ventricular dysfunction and elevated cardiac biomarkers, low-dose CDT, with or without ultrasound, reduced early clinical deterioration in two trials with differing eligibility criteria: HI-PEITHO required troponin elevation and at least two additional markers of cardiorespiratory compromise, whereas PRAGUE-26 required troponin or natriuretic peptide elevation. No statistically significant difference in major bleeding was detected, although mortality did not improve and intracranial haemorrhage occurred. MT accelerated right ventricular recovery versus anticoagulation and, in an open-label trial against CDT, improved a composite driven by deterioration and intensive care use. Guidelines predate most of these data and differ between continents: the 2019 European Society of Cardiology guideline and European consensus documents reserve transcatheter treatment mainly for high-risk PE with contraindicated or failed thrombolysis and for rescue after deterioration, whereas the 2026 American Heart Association/American College of Cardiology guideline allows its consideration in incipient cardiopulmonary failure. This review summarises techniques, evidence and recommendations, and it discusses patient selection, comparative effectiveness and long-term outcomes. Pending updates, decisions should be individualised by multidisciplinary PE response teams.

This article summarises clinical and research insights into the prevention and therapy of respiratory infections, along with consensus statements and key guideline recommendations reported at the 2025 #ERSCongress https://bit.ly/4qd6BXW