1925. Prevalence of SARS-CoV-2 Infection in Immunocompromised Patients Following Receipt of Tixagevimab/Cilgavimab

Abstract Background Tixagevimab/cilgavimab (TC) was approved by the FDA in December 2021 for use as pre-exposure prophylaxis in patients with moderate to severe immune compromise. On February 24, FDA recommended a second dose for patients who received the original dosing because of decreased activity against Omicron subvariants. We were interested in reviewing TC experience in Minnesota. Methods Minnesota Department of Health established a voluntary TC patient registry in December 2021, including date of treatment, COVID-19 vaccination status and immunocompromising conditions. Patients were matched to state COVID-19 case data from December 1, 2021 to April 22, 2022, to examine occurrence of SARS-CoV-2 infection (a positive test by PCR or antigen) following receipt of TC. Results Data were available for 289 patients, representing 5-10% of all patients treated with TC in Minnesota. 53% were male with a median age of 62 (IQR 48-70). 13 patients (4.5%) had not received COVID-19 vaccine at the time of initial TC dose. 128 patients (44%) received 2 doses of TC. Immunocompromising conditions included: hematological malignancy (114, 39.4%), treatment with immunosuppressant medications (113, 39.1%), solid organ transplant (45, 15.6%), and stem cell transplant (13, 4.5%). 5 patients (1.7%) had a positive SARS-CoV-2 test (4 PCR, 1 antigen) following receipt of TC (Table 1); patients tested positive on days 7, 11, 13, 17 and 48/70. Three patients were on rituximab and 2 had hematological malignancy. All 5 had received 3 doses of COVID-19 vaccine prior to receipt of TC. Variant information was available for 2 patients: BA.1 and BA.1.1. 1 patient required hospitalization for COVID-19 and died 39 days after the positive test but had 3 subsequent negative tests before discharge; death was attributed to underlying malignancy. Table 1: Characteristics of patients with positive SARS-CoV-2 tests following treatment with tixagevimab/cilgavimab. Conclusion In a convenience sample of 289 patients who received TC, 5 patients had COVID-19, with 3 occurring within the SARS CoV-2 incubation period following receipt of TC. One of the other patients was positive after receiving 2 doses of TC. Following effectiveness of TC will be useful as SARS CoV-2 continues to evolve. Disclosures All Authors: No reported disclosures.