Clinical, immunological and virological SARS-CoV-2 phenotypes in obese and non-obese military health system beneficiaries.

BACKGROUND: The mechanisms underlying the association between obesity and COVID-19 severity remain unclear. After verifying that obesity was a correlate of severe COVID-19 in U.S. Military Health System (MHS) beneficiaries, we compared immunological and virological phenotypes of SARS-CoV-2 infection in both obese and non-obese participants. METHODS: COVID-19-infected MHS beneficiaries were enrolled, and anthropometric, clinical, and demographic data were collected. We compared the SARS-CoV-2 peak IgG humoral response and RT-PCR viral load in obese and non-obese patients, stratified by hospitalization, utilizing logistic regression models. RESULTS: 511 COVID-19 patients were analyzed, among whom 24% were obese and 14% severely-obese. Obesity was independently associated with hospitalization (aOR = 1.91, 95% CI = 1.15-3.18) and need for oxygen therapy (aOR = 3.39, 95% CI = 1.61-7.11). In outpatients, severely-obese had a log10 (1.89) higher N1 genome equivalents (GE)/reaction and log10 (2.62) higher N2 GE/reaction than non-obese (p = 0.03 and p < 0.001, respectively). We noted a correlation between BMI and peak anti-spike protein IgG in inpatients and outpatients (coefficient = 5.48, p < 0.001). CONCLUSIONS: Obesity is a strong correlate of COVID-19 severity in MHS beneficiaries. These findings offer new pathophysiological insights into the relationship between obesity and COVID-19 severity.