RETN and COVID-19: As adipose tissue was recently shown to influence both the COVID-19 outcome and antibody generation targeting spike protein of SARS-CoV2 after vaccination or natural infection, we next explored the serum levels of ten well described adipose tissue-related factors: MCP-1/CCL2, CRP, factor D, PAI-1/SERPINE1, interleukins 6 (IL-6) and 10 (IL-10), adiponectin, leptin, resistin, and TNF-α.