Methods
Study population, setting, and data collection: Sixteen
seronegative controls and a total of 125 in-patients individuals were
recruited, following informed consent, for the study from the COVID Care
Centres associated with BYL Nair hospital and T N medical college,
Municipal Corporation of Greater Mumbai (MCGM), Mumbai following
approval of institutional ethics committees. We obtained demographic
data, clinical history at presentation, and laboratory results during
admission.
Blood samples for the study were handled in accordance with ICMR
guidelines for biosafety. 1-3ml of whole blood was collected in EDTA
vacutainers. Aliquots of whole blood were processed for absolute cell
count and immunophenotyping as described below. Plasma was separated by
centrifugation at 400 g for 10 minutes. IgG and IgM antibodies against
SARS-CoV-2 were detected in fresh plasma samples using Rapid test from
Voxpress (Voxtur Bio LTD, India) and Chemiluminescence immunoassay
(CLIA) directed against SARS -CoV-2 anti-NC IgG. Remaining plasma
samples were aliquoted and stored at -800 C until
batch analysis of cytokines, LPS (Lipopolysaccharide) and Soluble MAdCAM
(sMAdCAM).