Persistent symptoms for groups 1-3 for consistency.

Inclusion Criteria:

1. Aged 18 years or older

2. History of acute COVID-19 infection (medically recorded)

3. Symptoms of fatigue and, shortness of breath and/or, joint pain and/or, problems
with memory and concentration which have been present for more than a period of 6
months post infection

4. Nonsteroidal anti-inflammatory drugs (NSAIDs such as ibuprofen, diclofenac, aspirin,
etc.) must have been stopped at least 48 hours prior to admission to the clinical
research centre (evaluation through questionnaire).

5. Willing and able to sign the ICF and comply with study procedures.

Exclusion Criteria:

1. Taking immunosuppressive medication (including corticosteroids), or receiving
chemotherapy, cytokine or anti-cytokine therapy, or antithrombotic medication
(evaluation through questionnaire).

2. Significant and/or acute illness within 5 days prior to admission that may impact
safety assessments, in the opinion of the Investigator.

3. Participants who are, in the opinion of the Investigator, not suitable for enrolment
for another reason. For example, participants with: cognitive impairment or severe
mental health conditions that might affect their ability to provide informed consent
or follow study procedures; non-adherence risk where participants are unlikely to
follow study protocols; participants with other chronic inflammatory conditions not
under investigation e.g. inflammatory bowel disease, COPD that may have immune
profiles that differ from the study's intended populationI