Study design and sampling of peripheral blood

The study population included individuals admitted to the University of Miami Hospital with COVID19 infection confirmed via RT-PCR from nasopharyngeal swabs. Four hundred RT-PCR confirmed COVID19 patients were enrolled. Out of the 400 COVID-19 patients, 100 were consented to participate in the COVID19 biobank. Figure 1 shows the study algorithm. Serum samples were used to measure IgG against N-protein and whole blood was used for SARS-CoV2 RT-PCR.

Shows the study algorithm.

All 100 serum samples were enrolled for IgG measurement. The single to cut off (S/Co) ratio was measured for all samples.

Fifteen patients were randomly selected for whole blood RNA extraction. Five patients with high IgG titers (defined as S/Co ratio > 1.5), 5 with positive IgG but S/Co ratio < 1.5, and 5 with undetectable IgG levels were selected at enrollment.

Peripheral blood samples were collected following enrollment and processed by centrifugation at 1800 g for 30 min. Serum and whole blood were aliquoted into 2 ml cryogenic tubes and stored at –80 C immediately for later analysis.