Monoclonal antibody treatment drives rapid culture conversion in SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monoclonal antibodies (mAbs) are among the treatments recommended for high-risk ambulatory persons with coronavirus 2019 (COVID-19). Here, we study viral culture dynamics post-treatment in a subset of participants receiving the mAb bamlanivimab in the ACTIV-2 trial (ClinicalTrials.gov: NCT04518410). Viral load by qPCR and viral culture are performed from anterior nasal swabs collected on study days 0 (day of treatment), 1, 2, 3, and 7. Treatment with mAbs results in rapid clearance of culturable virus. One day after treatment, 0 of 28 (0%) participants receiving mAbs and 16 of 39 (41%) receiving placebo still have culturable virus (p < 0.0001). Recrudescence of culturable virus is detected in three participants with emerging mAb resistance and viral RNA rebound. While further studies are necessary to fully define the relationship between shed culturable virus and transmission, these results raise the possibility that mAbs may offer immediate (household) and public-health benefits by reducing onward transmission.
Competing Interests: Declaration of interests J.B., M.C.C., R.D., J. Regan, J.P.F., C.R.C., M.D.H., J. Ritz, C.M., J.A.D., A.C.J., R.W.C., J.S.C., and A.K.B. report no competing interests. K.W.C. reports research grant support to the institution from Merck Sharp & Dohme. A.N. and P.K. are employees and shareholders of Eli Lilly. A.L.G. declares central testing contracts with Abbott and research support from Gilead and Merck outside of the submitted work. W.A.F. reports research funding from Ridgeback Biopharmaceuticals and consultancy fees from Roche and Merck and serves on adjudication committees for Janssen and Syneos. E.S.D. reports consulting fees from Gilead Sciences and Merck and research support to the institution from Gilead Sciences and ViiV. J.J.E. reports serving as an ad hoc consultant to GSK/VIR and as data monitoring committee (DMC) chair for Adagio Phase III studies. D.M.S. reports consulting fees from the following companies: Fluxergy, Kiadis, Linear Therapies, Matrix BioMed, Arena Pharmaceuticals, VxBiosciences, Model Medicines, Bayer Pharmaceuticals, Signant Health, and Brio Clinical. J.Z.L. reports consulting for Abbvie and Recovery Therapeutics.
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