Monoclonal Antibody Treatment of Breakthrough COVID-19 in Fully Vaccinated Individuals with High-Risk Comorbidities

Background. Breakthrough coronavirus disease 2019 (COVID-19) may occur in fully vaccinated persons. Methods. We assessed the clinical outcomes of breakthrough COVID-19 in fully vaccinated individuals. Results. In this cohort of 1395 persons (mean age, 54.3 years; 60% female; median body mass index, 30.7) who developed breakthrough COVID-19, there were 107 (7.7%) who required hospitalization by day 28. Hospitalization was significantly associated with the number of medical comorbidities. Antispike monoclonal antibody treatment was significantly associated with a lower risk of hospitalization (odds ratio, 0.227; 95% confidence interval, 0.128-0.403; P<.001). The number needed to treat (NNT) to prevent 1 hospitalization was 225 among the lowest risk patient group compared with NNT of 4 among those with highest numbers of medical comorbidity. Conclusions. Monoclonal antibody treatment is associated with reduced hospitalization in vaccinated high-risk persons with mild to moderate COVID-19.