CD4 and Increased total eosinophil count: Vancomycin is a glycopeptide antibiotic that activates T-cells isolated from patients with drug reaction with eosinophilia and systemic symptoms following vancomycin treatment (Nakkam et al., 2021), and has been shown to activate CD4+ and CD8+ T-cells from healthy donors (irrespective of whether they express the HLA risk allele A*32:01; Konvinse et al., 2019), via a direct binding interaction with HLA and T-cell receptors (Ogese et al., 2021).