Inclusion Criteria:  Healthy volunteers with a booking for COVID-19 vaccination slot as per government guidelines Aged 18-60 Volunteers who are willing to sign the consent form  Exclusion Criteria:  Aged <18 or >60 years Healthy subjects unwilling to consent Pregnant, or any possibility that a subject may be pregnant History of any serious illnesses, including recent infections or trauma Subjects taking systemic medication (other than the oral contraceptive pill) Subjects with self-reported use of mouthwash or tongue scrapes Subjects with recent (2 weeks) or current antibiotic use Subjects with a history, or recent treatment of (within last 3 months) any oral condition (excluding caries), including gingivitis, periodontitis and halitosis Subjects with a history of COVID-19 vaccination Subjects with any history of a blood-borne infectious