Survivors and control cohorts: In order to be eligible to participate in this study as a survivor or as a control, an individual must meet all of the following criteria: 1. Stated willingness to comply with all study procedures and availability for the duration of the study. 2. Male or female aged 0 to 21 years (at the NIH CC, minimum age is 3 years). 3. Willing to allow storage of samples and data for future research. 4. At the NIH CC: Has a physician or clinic outside NIH to manage underlying medical conditions, or agrees to establish care with an outside physician or clinic for any medical conditions requiring treatment that may be diagnosed as a result of protocol participation. In addition, an individual must meet all criteria for one of the following cohorts. Symptomatic survivor cohort (including MIS-C): 1. Documented prior COVID-19 or MIS-C as evidenced by one of the following: 1. detection of SARS-CoV-2 RNA or antigen in NP swab, saliva, sputum, or other sample source with Emergency Use Authorization (EUA)/approval from the US Food and Drug Administration (FDA) and a history of clinical manifestation compatible with COVID-19*; or 2. positive SARS-CoV-2 antibody test using an assay that has received EUA from the FDA (negative SARS-CoV-2 RNA or antigen or never tested), and a history of clinical manifestation compatible with COVID-19*; or 3. meeting CDC case definition for MIS-C (see Appendix 1). 2. Onset of COVID-19/MIS-C symptoms is at least 4 weeks before baseline visit. *one or more of the following: ageusia, anosmia, chills, confusion, cough, rash, "COVID toes", diarrhea, dyspnea, fatigue, fever, headache, myalgia, nausea/vomiting, pneumonia, rhinorrhea. Asymptomatic survivor cohort: 1. Documented prior SARS-CoV-2 infection as evidenced by one of the following: 1. detection of SARS-CoV-2 RNA or antigen in NP swab, saliva, sputum, or other sample source with EUA/approval from the FDA without history of clinical manifestation compatible with COVID-19; or 2. positive SARS-CoV-2 antibody test using an assay that has received EUA from the FDA without history of clinical manifestation compatible with COVID-19*. 2. Positive SARS-CoV-2 RNA or antigen test is at least 4 weeks before baseline visit. - one or more of the following: ageusia, anosmia, chills, confusion, cough, rash, "COVID toes", diarrhea, dyspnea, fatigue, fever, headache, myalgia, nausea/vomiting, pneumonia, rhinorrhea. Healthy contact (control) cohort: 1. No diagnosis of SARS-CoV-2 infection or current symptoms suggestive of COVID-19 and meets one of the following criteria: 1. Lived in the same household as a participant with SARS-CoV-2 infection during the time of illness, or was within approximately 6 feet (2 meters) of the participant for a prolonged period of time, or having direct contact with infectious secretions of a COVID-19 case (e.g., being coughed on). 2. Lives in an area affected by SARS-CoV-2 infection Parents and guardians: In order to participate in this study as a parent or guardian, an individual must meet all of the following criteria: 1. Is a parent or guardian of a participant enrolled as a survivor or as a control. 2. Stated willingness to comply with all study procedures and availability for the duration of the study. 3. Willing to allow storage of data for future research.

Survivors and controls: An individual who meets any of the following criteria will be excluded from participation in this study: 1. Any symptoms suggestive of an ongoing infection within 15 days of baseline visit, including but not limited to fever > 38.2 °C, new or worsening respiratory symptoms (e.g., cough, dyspnea), or new or worsening gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea or abdominal pain). 2. Any medical or mental health condition that, in the judgement of the principal investigator, would make the volunteer unable to participate in the study. 3. Pregnancy. Parents and guardians: An individual who meets any of the following criteria will be excluded from participation in this study: 1. Any medical or mental health condition that, in the judgement of the principal investigator, would make the volunteer unable to participate in the study. Co-enrollment: Participants may be co-enrolled in other clinical studies, including observational studies and therapeutic trials. However, the study staff should be informed of co-enrollment.