Introduction
Immunocompromised patients are at high risk of severe COVID-19. Since they might not elicit an adequate immune response after vaccination, passive immunization using ex-vivo produced neutralizing antibodies is one of the key therapeutic options in such populations1. Monoclonal anti-spike antibodies have shown a great risk reduction of hospitalization or death in immunocompetent patients2,3. However, emerging Omicron SARS-CoV-2 variants appeared to be completely or partially resistant to available monoclonal antibodies4. Early treatment with COVID-19 convalescent plasma (CCP) in unvaccinated immunocompetent patients has been shown to be associated with a lower risk of hospitalization5. Therefore, even if monoclonal antibodies seem associated with a greater risk reduction of disease progression than CCP, the polyclonal characteristics of CCP might be of particular interest in the context of emergence of new variants. Early in the pandemic, high titer CCP has shown some efficacy in B-cell depleted patients6,7 but little is known on the efficacy of CCP in immunosuppressed patients infected by Omicron variant. Here, we report a case series of 75 immunocompromised patients infected by the BA.1 or BA.2 Omicron SARS-CoV-2 subvariants and treated with high titer Omicron CCP.