biostudies-literatureUnknownVillas-Boas L<h4>Objectives</h4> The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. <h4>Methods</h4> Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. <h4>Results</h4> Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies againClinics (Sao Paulo, Brazil)https://www.ebi.ac.uk/biostudies/studies/S-EPMC9212906biostudies-literatureAbsence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variantPMC9212906Paula AManuli EPaiao HLeal FMendes-Correa MTozetto-Mendoza TSilva AWitkin SVillas-Boas LFerraz ABierrenbach ASabino EfalseAbsence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variant<h4>Objectives</h4> The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. <h4>Methods</h4> Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. <h4>Results</h4> Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies again2022-01-01T00:00:00Z2022 Jun2025-04-19T19:20:30.485Z2025-04-19T19:20:30.485ZS-EPMC9212906