CD19 and COVID-19: The increased frequencies of LDGs in mild and severe COVID-19 as compared to HC was confirmed by conventional gating techniques of CD66 and CD15 co-expression in live CD3-/CD14-/CD19-/CD56- populations (mild COVID-19, p < 0.01; severe COVID-19 p < 0.0001) (Fig 1C, representative gating in Fig 1B).