Coronavirus disease 2019 (COVID- 19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first surfaced at the end of 2019 and quickly escalated into a global health crisis. Although the WHO announced in 2023 that COVID-19 is no longer considered a public health emergency of international concern, it remains a severe infectious disease and still results in many hospitalizations and deaths. The principles of prevention against SARS-CoV-2 include hand washing, mask usage, ventilation, maintenance of sufficient distance from others and vaccination. Various vaccines have been developed using different technologies such as mRNA and recombinant proteins. 5)6) These vaccines have been clinically evaluated for their effectiveness in inducing antibody response and T-cell activation, thus preventing infection and halting disease progression. However, vaccines do not fully prevent infection, especially with the emergence of new variants such as Omicron 8)9) . Thus, additional strategies are needed, particularly for preexposure prophylaxis (PrEP) in high-risk groups. Immunocompromised individuals are considered a high-risk group for severe COVID-19 and prolonged viral shedding. 11) These individuals must be vaccinated to prevent infection; however, the WHO announced that the efficacy of mRNA vaccines is lower in immunocompromised patients than in individuals who are not immunocompromised. 12) SARS-CoV-2-neutralizing antibody drugs are an option for PrEP for immunocompromised individuals who may not achieve a sufficient immune response with vaccination. 13) However, the efficacy of antibody drugs can change as viruses mutate. Tixagevimab co-packaged with cilgavimab (Evusheld ® ) was granted emergency use authorization by the Food and Drug Administration for PrEP in December 2021, but its use is not currently permitted in the US owing to the drug's reduced effectiveness against some SARS-CoV-2 variants. While the development of new antibody drugs is ongoing, new approaches are necessary for PrEP in immunocompromised patients to prepare for emergence of new variants.