Chart review of previously consented participants from the entire NIH RECOVER cohort, comprised of 15,000 infected and 2,600 noninfected patients across the country.

Participants will perform a needle fat biopsy for tissue harvesting in the subacute phase (15-30d) of Covid-19 infection or as a healthy control. Our goal is 20 COVID-19 infected participants and 10 healthy controls.

We are looking for 20 healthy controls for 2 in-person visits on separate days.

1. An Insulin Sensitivity Test (SSPG: Steady State Plasma Glucose) is performed to determine if the participant is insulin-sensitive or insulin resistant.
2. A Needle Fat Biopsy: After an overnight fast, approximately 1-2 grams of subcutaneous fat will be removed by a needle. Patients will have a local anesthetic prior to the procedure.

After an overnight fast, approximately 1-2 grams of subcutaneous fat will be removed by a needle. Participants will have a local anesthetic prior to the procedure. The needle fat biopsy will be repeated at quarterly intervals for one year (every 3 months). We will also draw 1 10mL tube of blood at each biopsy for measurement of inflammatory cytokines.

Investigate the relationship between insulin resistance, as described by triglyceride/HDL-cholesterol ratio, and incident PASC (long COVID).

Investigate the expression of viral RNA in adipose tissue in response to COVID-19 infection. Compare adipose tissue transcripts such as known MODY transcription factors measured by PCR between COVID-19 infected participants and healthy controls.

Investigate inflammatory response to PPARgamma agonist (drug) and other compounds tested in vitro in human fat cells. Compare plasma inflammatory cytokine levels in serum samples as measured by Luminex immunoassay between participants identified as Insulin Sensitive (IS) and Insulin Resistant (IR) using the 2-stage Steady State Plasma Glucose test.

Investigate the expression of inflammatory genes in adipose tissue in response to COVID-19 infection. Compare adipose tissue transcripts such as defensin chemokine receptors and platelet activation factors measured by PCR between COVID-19 infected participants and healthy controls.