Tixagevimab–cilgavimab is the only nonvaccine drug currently authorized in the United States for the prevention of COVID-19 infection in individuals who are moderately to severely immunocompromised or unable to receive COVID-19 vaccination. Tixagevimab–cilgavimab is composed of two monoclonal antibodies, tixagevimab and cilgavimab, which bind to the spike protein of the SARS-CoV-2 virus. This blocks the ability of the virus to infect cells. Tixagevimab–cilgavimab is administered as two intramuscular injections consisting of tixagevimab 300 mg (3 ml) and cilgavimab 300 mg (3 ml). After patient injections, the nurse monitors the patient for one hour in the clinic. Tixagevimab–cilgavimab has been well tolerated, with mild headache, fatigue, and cough being the most commonly reported side effects.