Absence 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

Author(s):Show less -

Lucy Santos Villas-Boas ; Anderson Vicente de Paula ; Almir Ribeiro da Silva Jr. ; Heuder Gustavo Oliveira Paiao ; Tania Regina Tozetto-Mendoza ; Erika Regina Manuli ; Fábio Eudes Leal ^[7] ; Andrea de Barros Coscelli Ferraz ^[8] ; Ester Cerdeira Sabino ; Ana Luiza Bierrenbach ^[10] ; Steven Sol Witkin ^[11] ; Maria Cassia Mendes-Correa

• Document type: Journal article
• Source: Clinics; v. 77, 2022-08-08.

Abstract

Abstract Objectives: 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. Methods: 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. Results: Following 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. Conclusions: Neutralizing 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. HIGHLIGHTS Individuals previously infected with SARS-CoV-2 ancestral strain do not develop neutralizing antibodies against the Omicron variant. Omicron variant escapes immune response after SARS CoV-2 previous infection with the SARS CoV-2 Gamma variant. Individuals previously infected with SARS-CoV-2 ancestral strain or with SARS-CoV-2 Gamma variant will likely have little protection if subsequently exposed to the Omicron variant. (AU)

• FAPESP's process: 20/05623-0 - SARS-CoV2 detection, in different biological specimens, among people infected with this virus
• Grantee: Maria Cássia Jacintho Mendes Corrêa
• Support Opportunities: Regular Research Grants