biostudies-literatureUnknown150Eberhardt ATThe SARS-CoV-2 Omicron variant has increased infectivity and immune escape compared with previous variants, and caused the surge of massive COVID-19 waves globally. Despite a vast majority (~90%) of the population of Santa Fe city, Argentina had been vaccinated and/or had been infected by SARS-CoV-2 when Omicron emerged, the epidemic wave that followed its arrival was by far the largest one experienced in the city. A serosurvey conducted prior to the arrival of Omicron allowed to assess the acquired humoral defences preceding the wave and to conduct a longitudinal study to provide individual-level real-world data linking antibody levels and protection against COVID-19 during the wave. A very large proportion of 1455 sampled individuals had immunological memory against COVID-19 at the arrivEpidemiology and infectione187https://www.ebi.ac.uk/biostudies/studies/S-EPMC9947048biostudies-literaturePreceding anti-spike IgG levels predicted risk and severity of COVID-19 during the Omicron-dominant wave in Santa Fe city, Argentina.PMC9947048Simoncini MViotto EGaloppo GPina CSklar DMarignac VRacca AJunges CGenolet ABotto CPalavecino CEberhardt ATParachu-Marco VValli FBeccaria CFernandez HMunoz de Toro MMingo GArmando GBossio JCAimar HBeldomenico PMScarpa LArce SFacelli FfalsePreceding anti-spike IgG levels predicted risk and severity of COVID-19 during the Omicron-dominant wave in Santa Fe city, Argentina.The SARS-CoV-2 Omicron variant has increased infectivity and immune escape compared with previous variants, and caused the surge of massive COVID-19 waves globally. Despite a vast majority (~90%) of the population of Santa Fe city, Argentina had been vaccinated and/or had been infected by SARS-CoV-2 when Omicron emerged, the epidemic wave that followed its arrival was by far the largest one experienced in the city. A serosurvey conducted prior to the arrival of Omicron allowed to assess the acquired humoral defences preceding the wave and to conduct a longitudinal study to provide individual-level real-world data linking antibody levels and protection against COVID-19 during the wave. A very large proportion of 1455 sampled individuals had immunological memory against COVID-19 at the arriv2022-01-01T00:00:00Z2022 Nov2025-04-21T16:10:22.582Z2025-04-21T16:10:22.582ZS-EPMC99470483632583710.1017/S0950268822001716