Inclusion Criteria:  • South Asian and White British persons and those diagnosed with symptomatic or asymptomatic COVID-19 infection.  Aged 18 or over. Able to understand and consent. Uninfected subjects: no history of COVID-19; not vaccinated; (negative for anti-SARS-CoV2 nucleoprotein antibodies at lab) For patient groups: Confirmed COVID-19 positivity, symptoms and symptom onset within the past 21 days; Be recently hospitalised with COVID-19 disease; Have COVID-19 disease proven by PCR testing for SARS-CoV-2 within the last 21 days; COVID disease severity graded as per NIH/WHO. Recovered groups: Have had COVID-19 disease proven by PCR testing for SARS-CoV-2. COVID disease severity graded as per WHO or NIH equivalent criteria Those willing to participate on a single occasion but unwilling to participate with longitudinal samples will not be excluded. Smoking, obesity, diabetes, heart disease, antibiotics or treatment related to COVID is not excluded.  Exclusion Criteria:  • Those patients unwilling to participate, those unable to understand sufficiently to give informed consent and those unable to participate due to the severity of COVID-19 disease. Those patients classified as not either South Asian or White British heritage.  Patients with malignancy, pregnancy, long term immune suppression, inability to give informed consent, not willing or able to have oral examination. Diabetes not excluded but screening for diabetes will be performed: glucose will be assessed in blood/serum sample (150ul).  Exclusion criteria summary:  Critically ill participants who cannot give informed consent Those who are not willing to have an oral examination, or donate blood or saliva samples. Those who cannot chew / drool to provide a SWMF sample due to severe/critical medical conditions Participants with known malignancies or who are pregnant Participants who are on long-term immunosuppressants (e.g. for autoimmune diseases) Participation in other current research that is designed to, or is expected to alter the immune response. Inability to communicate, understand or read English.