Inclusion Criteria:  ≥ 50 years with ≥ 2 chronic comorbidities Highly suspected bacterial infection based on clinical or radiologic evidence ≥ 2 systemic inflammatory response syndrome (SIRS) criteria Actual/anticipated admission to intensive care unit (ICU) Anticipated length of hospital stay ≥ 5 days  Exclusion Criteria:  Pregnancy Underlying immunosuppression (solid organ transplant, hematopoietic stem cell transplant, neutropenia, HIV infection, long-term corticosteroid use (≥ 20 mg prednisone equivalents for ≥ 14 days), immunosuppressants, radiation, chemotherapy, immune-modifying biologics, viral hepatitis, or systemic autoimmune diseases) Current immunotherapy use Confirmed COVID-19 infection