This is a longitudinal study in which participants that have been confirmed by a National Health Service (NHS) swab test as COVID-19 positive will be asked to provide faecal and saliva samples, and complete short health/lifestyle questionnaires at the time of sampling (referred to as a sample set). The number of sample sets collected from any participant will be dependent on how long the SARS-CoV-2 virus persists within the stool. The investigators aim to collect a minimum of 4 and a maximum of 8 sample sets, and will target all COVID-19-positive subjects, with the exception of those severally ill (e.g. in the intensive care unit (ICU)). The investigators aim to recruit a minimum of 100 and up to 200 participants. To obtain the desired numbers, it may be necessary to continue recruitment during any further United Kingdom (UK) COVID-19 infection peaks.

Approaching participants will mainly be performed in two ways:

1. the Norfolk and Norwich University Hospital (NNUH) online booking system for SARS-CoV-2 testing will have a link to the Quadram Institute Bioscience (QIB) study webpage, which will include the Participant Information Sheet (PIS). When the NHS testing service informs individuals of their test results by text message, the QIB study page Uniform Resource Locator (URL) will be added to the end of the text message for COVID-19 'positive' results. In addition, testing service staff will remind the potential participants of the study if they contact individuals by telephone to inform them of positive COVID-19 results from the test-centre swabs. During this call, potential participants will be asked to provide verbal consent for the study team to contact them for arranging a study talk. Potential participants will be able to contact QIB directly to express interest by email or phone, and can contact QIB to request a hard copy of the PIS be posted to them.

2. NNUH staff will approach in-ward patients positive for COVID-19. Should the patients be interested in learning more, a NNUH staff member will provide them with a copy of the PIS and be available to answer any questions the patients may have. Fully informed written consent of hospitalised COVID-19 patients will be performed by an NNUH nurse using the study consent form.

   • Participants recruited from a non-hospital setting will be consented, using the same consent form as hospitalised patients, over the telephone/internet video by members of the study team who have received the QIB consent training.

Signed copies of these forms will be collected along with the first sample set. In both scenarios, each point will be explained and all questions will be answered to ensure that the participant is fully informed.

The investigators will also be asking participants whether they would be willing to consent to their samples being stored at the Norwich Research Park Biorepository, and whether they would consent to being re-contacted by researchers about possible future research for which they may be eligible. These are both optional, i.e. should the patient choose not to consent to either or both, they will still be able to participate in the study.

Following the recruitment of COVID-19 positive participants the investigators will ask for an initial faecal and saliva sample, and request that the participant completes a health/lifestyle questionnaire. If participants show symptoms the investigators will collect a second set of samples after 48h of symptoms disappearance (specifically, a lack of fever), whereas if participants are asymptomatic the investigators will collect the second set of samples after 7 days. For both types of participants, the investigators will then collect 2 more sample sets every 7 days (day 7: set 3, day 14: set 4). Should either sample test positive then the investigators will continue the same 7-day sampling process until both samples are negative for two consecutive sample sets, or they have given a total of eight faecal and saliva samples. At either of these points, whichever is earliest, the participant will have then completed the study

Inclusion Criteria:

• Men and women aged >18 years
• Those that live or work within a 40-mile radius of Norwich/Norfolk and Norwich University Hospital
• Those who are confirmed COVID-19 positive by an NHS swab test

Exclusion Criteria:

• Those who are admitted to an NHS Intensive Care Unit
• Any person related to, or living with, any member of the study team
• Those who are part of the Line Manager/supervisory structure of the Chief Investigators
• Those who are unable to provide written informed consent

Those who have tested positive for COVID-19, whether isolated at home or admitted to the Norfolk and Norwich University Hospital. Those admitted to the intensive care unit will not be eligible for the study