Dobaño, CarlotaRamírez-Morros, AnnaAlonso, SelenaRubio, RocíoRuiz-Olalla, GemmaVidal Alaball, JosepMacià, DídacMiró Catalina, QueraltVidal, MartaFuster Casanovas, AinaPrados de la Torre, EstherBarrios, DianaJiménez, AlfonsZanoncello, JasminaRodrigo Melero, NataliaCarolis, CarloIzquierdo, LuisAguilar, RuthMoncunill, GemmaRuiz-Comellas, Anna2023-01-182023-01-182022Dobaño C, Ramírez-Morros A, Alonso S, Rubio R, Ruiz-Olalla G, Vidal-Alaball J, Macià D, Catalina QM, Vidal M, Casanovas AF, Prados de la Torre E, Barrios D, Jiménez A, Zanoncello J, Melero NR, Carolis C, Izquierdo L, Aguilar R, Moncunill G, Ruiz-Comellas A. Sustained seropositivity up to 20.5 months after COVID-19. BMC Med. 2022 Oct 13;20(1):379. DOI: 10.1186/s12916-022-02570-31741-7015http://hdl.handle.net/10230/55322This study evaluated the persistence of IgM, IgA, and IgG to SARS-CoV-2 spike and nucleocapsid antigens up to 616 days since the onset of symptoms in a longitudinal cohort of 247 primary health care workers from Barcelona, Spain, followed up since the start of the pandemic. The study also assesses factors affecting antibody levels, including comorbidities and the responses to variants of concern as well as the frequency of reinfections. Despite a gradual and significant decline in antibody levels with time, seropositivity to five SARS-CoV-2 antigens combined was always higher than 90% over the whole study period. In a subset of 23 participants who had not yet been vaccinated by November 2021, seropositivity remained at 95.65% (47.83% IgM, 95.65% IgA, 95.65% IgG). IgG seropositivity against Alpha and Delta predominant variants was comparable to that against the Wuhan variant, while it was lower for Gamma and Beta (minority) variants and for IgA and IgM. Antibody levels at the time point closest to infection were associated with age, smoking, obesity, hospitalization, fever, anosmia/hypogeusia, chest pain, and hypertension in multivariable regression models. Up to 1 year later, just before the massive roll out of vaccination, antibody levels were associated with age, occupation, hospitalization, duration of symptoms, anosmia/hypogeusia, fever, and headache. In addition, tachycardia and cutaneous symptoms associated with slower antibody decay, and oxygen supply with faster antibody decay. Eight reinfections (3.23%) were detected in low responders, which is consistent with a sustained protective role for anti-spike naturally acquired antibodies. Stable persistence of IgG and IgA responses and cross-recognition of the predominant variants circulating in the 2020-2021 period indicate long-lasting and largely variant-transcending humoral immunity in the initial 20.5 months of the pandemic, in the absence of vaccination.application/pdfeng© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data mainfo:eu-repo/semantics/articlehttp://dx.doi.org/10.1186/s12916-022-02570-3AntibodyCOVID-19DurationHealth care workersIgAIgGIgMKineticsSARS-CoV-2Seroprevalenceinfo:eu-repo/semantics/openAccess