Prevalence and clinical outcome of Omicron breakthrough infection in patients with hematologic disease: a prospective observational cohort study

Abstract

Abstract To explore the prevalence and outcomes of the severe acute respiratory syndrome virus-2 Omicron infection in hematologic disease (HD), we performed a prospective observational study on 922 patients with HD and 88 healthcare workers (HCW). We identified 75 and 12 Omicron breakthrough infections in HD and HCW, respectively. In multivariate analysis, older age and use of anti-CD20 antibody within one year were significant independent predictors of breakthrough infection in HD who received two doses of vaccination, but these were not significant for three doses. Of the 75 HD patients infected with Omicron, 66 had mild symptoms and recovered completely, while nine patients required oxygen therapy, three of whom eventually died. In nine patients with longitudinal polymerase chain reaction data available, the five patients who were treated with anti-CD20 antibodies plus bendamustine had prolonged viral shedding. The absolute T-cell subset counts were significantly lower in patients with prolonged viral shedding than in those without. Overall, the symptoms of Omicron infection in HD patients other than those with bendamustine were generally mild and prompt viral clearance was achieved. Even in immunocompromised HD patients, other than those treated with bendamustine, Omicron infection may not require the rigorous infection control as with previous variants.