INFECTED COHORT -- ADULTS WITH SUSPECTED SARS-COV-2 INFECTION -- An adult qualifies as having suspected SARS-CoV-2 infection if meeting criteria a, b or c below: 1. Patients who meet the following clinical criteria plus one of the epidemiological criteria: Clinical Criteria: Acute onset of fever and cough OR acute onset of any three of more of the following signs or symptoms: fever, cough, general weakness /fatigue, headache, myalgia, sore throat, coryza, dyspnea, anorexia/nausea/vomiting, diarrhea, altered mental status. Epidemiological Criteria: 1. Residing or working in an area with a high risk of transmission of virus: closed residential settings, humanitarian settings such as camp and camp-like settings for displaced persons; anytime within the 14 days before symptom onset; or 2. Residing or travel to an area with community transmission anytime within the 14 days before symptom onset; or 3. Working in any health care setting, including within health facilities or within the community; anytime within the 14 days before symptom onset. 2. A patient with severe acute respiratory illness: (acute respiratory infection with history of fever or measured fever of =38C°; and cough; with onset within the last 10 days; and requires hospitalization). 3. An asymptomatic person not meeting epidemiologic criteria with a positive SARS-CoV-2 Antigen-RDT. ADULTS WITH PROBABLE SARS-COV-2 INFECTION -- An adult qualifies as having probable SARS-CoV-2 infection if meeting any one of a-d below: 1. A patient who meets clinical criteria for suspected SARS-CoV-2 AND is a contact of a probable or confirmed case or linked to a COVID-19 cluster; 2. A suspect case with chest imaging showing findings suggestive of COVID-19 disease; 3. A person with recent onset of anosmia (loss of smell) or ageusia (loss of taste) in the absence of any other identified cause; 4. Death, not otherwise explained, in an adult with respiratory distress preceding death AND was a contact of a probable or confirmed case or linked to a COVID-19 cluster ADULTS WITH CONFIRMED SARS-COV-2 INFECTION -- An adult qualifies as having confirmed SARS-CoV-2 infection if meeting any one of a-d below: 1. Any person with a positive Nucleic Acid Amplification Test (NAAT); 2. Any person with a positive SARS-CoV-2 Antigen-RDT OR positive SARS-CoV-2 antibody test* AND meeting either the probable case definition or suspect criteria A OR B; 3. An asymptomatic person with a positive SARS-CoV-2 Antigen-RDT who is a contact of a probable or confirmed case 4. Any person with a positive SARS-CoV-2 nucleocapsid protein antibody test OR a positive SARS-CoV-2 spike protein antibody test IF not vaccinated - (*)This protocol modifies the WHO criterion b to add detectable SARS-CoV-2 antibody as a qualifying test. UNINFECTED COHORT -- ADULTS WITH NO SARS-COV-2 INFECTION -- - Does not meet WHO criteria for a suspected, probable, or confirmed case of SARS-CoV-2 infection, AND - Has a documented negative SARS-CoV-2 PCR test from a respiratory specimen in the past, if being enrolled as a post-acute control (see XII.H), AND - Has a documented negative SARS-CoV-2 PCR test from a respiratory specimen at the time of enrollment/screening, AND - Has a negative SARS-CoV-2 nucleocapsid protein antibody and spike protein antibody test (spike only if not vaccinated) at the time of enrollment, AND - Live in the same communities or recruited from the same sources as those in the SARS-CoV-2 infected cohort, AND - Note: uninfected individuals may participate independent of their vaccination status