Ethics Approval
The FluStudy2020 protocol was reviewed and approved by the institutional review board of the WIRB-Copernicus Group (study number: 1271500). Written informed consent was obtained from all the participants before their enrollment in the study. The HTRI study (NCT04245800) protocol was approved by the institutional review board of the WIRB-Copernicus Group (study number: 1271380), and written informed consent was obtained from all the participants before their enrollment in the study [