Moreira-Soto, AndresArguedas, MauricioBrenes, HebleenBuján, WillemCorrales-Aguilar, EugeniaDíaz, CeciliaEcheverri, AnnFlores-Díaz, MariettaGómez, AarónHernández, AndrésHerrera, MaríaLeón, GuillermoMacaya, RománKühne, ArneMolina-Mora, José ArturoMora, JavierSanabria, AlfredoSánchez, AndrésSánchez, LauraSegura, ÁlvaroSegura, EduardoSolano, DanielaSoto, ClaudioStynoski, Jennifer LVargas, MariángelaVillalta, MaurenReusken, Chantal, B. E. MDrosten, ChristianGutiérrez, José MaríaAlape-Girón, AlbertoDrexler, Jan Felix2025-07-092025-07-092022doi: 10.3389/fmed.2021.735853http://hdl.handle.net/20.500.11764/4906ARTICULOSARS-CoV-2 variants of concern show reduced neutralization by vaccine-induced and therapeutic monoclonal antibodies; therefore, treatment alternatives are needed. We tested therapeutic equine polyclonal antibodies (pAbs) that are being assessed in clinical trials in Costa Rica against five globally circulating variants of concern: alpha, beta, epsilon, gamma and delta, using plaque reduction neutralization assays. We show that equine pAbs efficiently neutralize the variants of concern, with inhibitory concentrations in the range of 0.146–1.078μg/mL, which correspond to extremely low concentrations when compared to pAbs doses used in clinical trials. Equine pAbs are an effective, broad coverage, low-cost and a scalable COVID-19 treatmentenCOVID-19ANTICUERPOS EQUINOSArticle