Evaluation of the tolerability of monoclonal antibody therapy for pregnant patients with COVID-19

Aim To evaluate the tolerability of casirivimab and imdevimab (CAS/IMB) therapy in pregnant women with COVID-19 in Japan and its impact on the neonate and process of delivery. Methods Eight cases of pregnancy complicated by COVID-19 and requiring hospitalization during the delta variant epidemic were included. Gestational age, initial symptoms, pregnancy complications and outcome, severity of illness, blood test findings at the time of treatment initiation and on days 3-5 after administration, body temperature at administration, and 8, 24, and 48 h post-administration, delivery outcome, and neonatal findings were recorded. Ten pregnant women who required hospitalization at the same time and did not receive CAS/IMB were used as controls. Results Of the eight cases, seven were mild, and one case was of moderate severity. Body temperature in the CAS/IMB group was significantly higher at 8 h post-administration than that at the time of administration. However, body temperature significantly reduced at 24 and 48 h post-administration in the CAS/IMB group compared with that in the control group. There were no apparent adverse events after CAS/IMB administration. Conclusions Maternal administration of CAS/IMB was safe. Although it was difficult to evaluate the improvement in disease by blood test findings, the fever improved within 24 h, which suggests rapid improvement in patient condition.