• Lucy Santos Villas-Boas, Anderson Vicente de Paula, Almir Ribeiro da Silva, Heuder Gustavo Oliveira Paiao, Tania Regina Tozetto-Mendoza, Erika Regina Manuli, Fábio Eudes Leal, Andrea de Barros Coscelli Ferraz, Ester Cerdeira Sabino, Ana Luiza Bierrenbach, Steven Sol Witkin, and Maria Cassia Mendes-Correa.
• Instituto de Medicina Tropical de Sao Paulo, Faculdade de Medicina da Universidade de Sao Paulo, São Paulo, SP, Brazil; Departamento de Moléstias Infecciosas e Parasitarias da Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP, Brazil.
• Clinics (Sao Paulo). 2022 Jan 1; 77: 100068.

ObjectivesThe 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.MethodsConvalescent 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.ResultsFollowing an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively.ConclusionsNeutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant.Copyright © 2022. Published by Elsevier España, S.L.U.

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