Quiroga, BorjaSoler, María JoséOrtiz, AlbertoJaravaca Mantecón, Carlos JesúsNava Pérez, NathashaSerra Martín, MartaSato, YurikaMarin Franco, Antonio JoséPazmiño Zambrano, Diana FlorLucena Valverde, RafaelOrtega Diaz, MayraCalderón González, CarmenCazorla López, Juan ManuelPereira, MónicaGonzález Parra, EmilioSánchez Horrillo, AnaSánchez González, CarmenToapanta, NéstorCigarrán Guldris, SecundinoSánchez Hernández, RosaPizarro Sánchez, SoledadMuñiz Rincón, MaríaGarcia-Fernández, NuriaBlanco Castro, NataliaCollantes Mateo, RocíoQuiroz Morales, Manuel AugustoEscamilla-Cabrera, BeatrizBerdud Godoy, IsabelGil-Casares Casanova, BeatrizLeyva, AlbaRojas, JoséGansevoort, Ron Tde Sequera, PatriciaSENCOVAC collaborative network2023-05-032023-05-032022-07-262048-8505http://hdl.handle.net/10668/19752Patients on hemodialysis are at high-risk for complications derived from coronavirus disease 2019 (COVID-19). The present analysis evaluated the impact of a booster vaccine dose and breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on humoral immunity 3 months after the booster dose. This is a multicentric and prospective study assessing immunoglobulin G anti-Spike antibodies 6 and 9 months after initial SARS-CoV-2 vaccination in patients on hemodialysis that had also received a booster dose before the 6-month assessment (early booster) or between the 6- and 9-month assessments (late booster). The impact of breakthrough infections, type of vaccine, time from the booster and clinical variables were assessed. A total of 711 patients [67% male, median age (range) 67 (20-89) years] were included. Of these, 545 (77%) received an early booster and the rest a late booster. At 6 months, 64 (9%) patients had negative anti-Spike antibody titers (3% of early booster and 29% of late booster patients, P = .001). At 9 months, 91% of patients with 6-month negative response had seroconverted and there were no differences in residual prevalence of negative humoral response between early and late booster patients (0.9% vs 0.6%, P = .693). During follow-up, 35 patients (5%) developed breakthrough SARS-CoV-2 infection. Antibody titers at 9 months were independently associated with mRNA-1273 booster (P = .001), lower time from booster (P = .043) and past breakthrough SARS-CoV-2 infection (P  In hemodialysis patients, higher titers of anti-Spike antibodies at 9 months were associated with mRNA-1273 booster, lower time from booster and past breakthrough SARS-CoV-2 infection.enAttribution-NonCommercial 4.0 Internationalhttp://creativecommons.org/licenses/by-nc/4.0/COVID-19SARS-CoV-2boosterhemodialysisvaccinationresearch article36147708open access10.1093/ckj/sfac169PMC9384616https://academic.oup.com/ckj/article-pdf/15/10/1856/45972293/sfac169.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC9384616/pdf