A Prospective Study to Evaluate the Role of T-Cell Dysfunction in Patients Who Present Symptoms Associated With Long COVID, Lyme Disease and Myalic Encephalomyelitis / Chronic Fatigue Syndrome Using the Vira Immune Fluorospot T Cell Assay

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