Inclusion Criteria:  Age 18-65 Meets NICE-defined post-COVID-19 syndrome (NICE Definition: Signs and symptoms that develop during or after an infection consistent with COVID-19, continue for more than 12 weeks and are not explained by an alternative diagnosis). To ensure the above criteria is met, participants will only be included in the study if they meet all eligibility criteria more than 12 weeks from their confirmed and documented positive polymerase chain reaction (PCR) SARS-CoV-2 test. Documented history of SARS-CoV-2 infection with typical symptoms, and requiring positive SARS-CoV-2 test (PCR, antigen or antibody) at some point during the course or (in the case of antibodies) also after the acute course of illness Subjective cognitive complaints as detected by the Perceived Deficits Questionnaire (PDQ)-5 Ability to provide written informed consent  Exclusion Criteria:  Current symptoms are fully explained by major depressive disorder or bipolar disorder. Pre-existing conditions that may cause cognitive impairment, or symptoms similar to those seen in post-COVID-19 syndrome (e.g., major neurocognitive disorder, schizophrenia, chronic fatigue syndrome [CFS]/ encephalitis meningitis [EM]), as assessed by Mini International Neuropsychiatric Interview (MINI) 7.0.2. Inability to follow study procedures. Known intolerance to vortioxetine and/or prior trial of vortioxetine with demonstrated inefficacy. Not currently taking any other antidepressant in the past 4 weeks. Current alcohol or substance use disorder. Inability to provide consent. Current alcohol and/or substance use disorder as confirmed by the M.I.N.I 7.0.2 Presence of comorbid psychiatric disorder that is a primary focus of clinical concern as confirmed by the M.I.N.I. 7.0.2. Medications approved and/or employed off-label for cognitive dysfunction (e.g., psychostimulants). Any medication for a general medical disorder that, in the opinion of the investigator, may affect cognitive function. Use of benzodiazepines within 12 hours of cognitive assessments. Consumption of alcohol within 8 hours of cognitive assessments. Physical, cognitive, or language impairments sufficient to adversely affect data derived from cognitive assessments. Diagnosed reading disability or dyslexia. Clinically significant learning disorder by history. Electroconvulsive therapy (ECT) in the last 6 months. History of moderate or severe head trauma (e.g., loss of consciousness for >1 hour), other neurological disorders, or unstable systemic medical diseases that in the opinion of the investigator are likely to affect the central nervous system. Pregnant and/or breastfeeding. Received investigational agents as part of a separate study within 30 days of the screening visit.