•The 1-year incidence estimate of breakthrough infections (BTIs)/hospitalization/death was 24%.•A greater risk of incident BTIs was observed with BA.5 and XBB/EG.•The search for a new prophylaxis is urgently needed. Whether pre-exposure prophylaxis (PrEP) with tixagevimab/cilgavimab 150 mg/150 mg (T/C) in individuals with hematologic disease (HD) may lead to a reduced risk of SARS-CoV-2 breakthrough infection (BTI)/hospitalization, or death in the Omicron era remains to be established. An observational study included participants with HD who received PrEP. BTIs were defined as SARS-CoV-2 positivity by reverse transcription-polymerase chain reaction. The incidence of BTIs (95% CI) and of BTIs/hospitalization/death was calculated using the Kaplan-Meier method and as the number of BTIs per 100 person-years of follow-up according to the circulating variant of concern (VoC). A Poisson regression model was used to evaluate the association between the rate of incidence and circulating VoCs after controlling for demographics and clinical factors. We included 550 HD patients: 71% initiated T/C PrEP when BA.5 was the most prevalent, followed by XBB/EG, BA.2, and BA.1 (19%, 7%, and 3%, respectively). Overall, the 1-year incidence estimate of BTIs/hospitalization/death was 24% (18.7-29.4%). A greater risk of incident infections was observed when BA.5 and XBB/EG sub-lineages circulated (aRR 5.05 2.17, 11.77; P < .001 and 3.82 1.50, 9.7; P = 0.005, compared to BA.1, respectively). The 1-year incidence of SARS-CoV-2 BTIs/hospitalization/death was 24% which is in line with what was observed in other similar studies. The risk appeared to be higher when more recent Omicron sub-lineages were circulating suggesting a reduction of in vitro neutralization.