Objectives: 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.
Methods: 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.
Results: 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).
Conclusions: 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.
Keywords: COVID-19; Hematologic disease; Pre-exposure prophylaxis; SARS-CoV-2; Tixagevimab/cilgavimab.
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