Endogenous interferon-beta but not interferon-alpha or interferon-lambda levels in nasal mucosa predict clinical outcome in critical COVID-19 patients independent of viral load

Although the subject of intensive preclinical and clinical research, controversy on the protective vs. deleterious effect of interferon (IFN) in COVID-19 remains. Some apparently conflicting results are likely due to the intricacy of IFN subtypes (type I: IFN-alpha/beta, type III: IFN-lambda), timing and mode of administration (nebulized/subcutaneous) and clinical groups targeted (asymptomatic/mild, moderate, severe/critical COVID-19). Within the COntAGIouS (COvid-19 Advanced Genetic and Immunologic Sampling) clinical trial, we investigated endogenous type I and type III IFNs in nasal mucosa as possible predictors of clinical outcome in critical patients, as well as their correlation to SARS-CoV-2 viral load, using nCounter technology. We found that endogenous IFN-beta expression in the nasal mucosa predicts clinical outcome, independent of viral replication or Apache II score, and should be considered as a prognostic tool in a precision medicine approach of IFN therapy in COVID-19 clinical management. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial NCT04327570 ### Funding Statement This work was funded by KU Leuven (internal fund and grant C14/17/084 and C16/17/010), UZ Leuven (KOOR project) and FWO (Fundamental Clinical Mandate 1833317N to JW, G0A0621N to JVW). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The COntaGIous clinical trial has been approved by the Ethical Committee of University Hospitals Leuven (belgium). All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data are available in the manuscript or upon request from the authors.