Inclusion Criteria:  Age ≥ 18 years old (under 18 years old - only if it is allowed under local regulations and with legal guardian's approval and consent if needed. COVID-19 virus infection status is known and verified 24 hours prior to a TERA.Bio test by RT-PCR and if required, a repeated PCR test based on symptomatic status and or / the CT value of the tested individual. Signed Informed consent form.  Exclusion Criteria:  Discrepancies to inclusion criteria Individuals under general anaesthesia Individuals lacking the capability to personally sign the consent form. Individuals lacking the capability to exhale breath.