RESUMO
Omicron s escape to vaccine-induced systemic antibody responses has been shown in several studies in Omicron-infected patients and vaccine controls. In the present study we compared mucosal antibody response to Omicron to mucosal antibody response to ancestral strain and Delta variant. This was done on nasal epithelial lining fluid (NELF) prospectively collected in 84 otherwise healthy healthcare workers who had never exhibited PCR-documented COVID-19 and had received three doses of the Pfizer-BioNTech COVID-19 mRNA vaccine. NELF was collected prior to Omicron detection in the geographical area of inclusion. We show that NELF antibodies from vaccinated individuals were less efficient at inhibiting the binding of the Omicron Spike protein to ACE-2 compared to those of Delta or the ancestral strain. These findings may explain the increased risk of onward transmission of Omicron, consistent with its successful global displacement of Delta in countries with a high vaccination coverage.
RESUMO
BackgroundMucosal antibodies can prevent virus entry and replication in mucosal epithelial cells and hence virus shedding. Preclinical and clinical studies have shown that a parenteral booster injection of a vaccine against a mucosal pathogen promotes stronger mucosal immune responses following prior infection compared to two injections of a parenteral vaccine. We investigated whether this was also the case for a COVID-19 mRNA vaccine. MethodsTwenty-three COVID-19 convalescent patients and 20 SARS-CoV-2-naive subjects were vaccinated with respectively one and two doses of the Pfizer-BioNTech COVID-19 RNA vaccine. Nasal Epithelial Lining Fluid (NELF) and plasma were collected before and after vaccination and assessed for Immunoglobulin (Ig)G and IgA to Spike and for their ability to inhibit the binding of Spike to its ACE-2 receptor. Blood was analyzed one week after vaccination for the number of Spike-specific Antibody Secreting Cells (ASCs) with a mucosal tropism. ResultsIn COVID-19 convalescent patients, a single dose of vaccine amplified pre-existing Spike-specific IgG and IgA antibody responses in both NELF and blood against both vaccine homologous and variant strains, including delta. These responses were associated with Spike-specific IgG and IgA ASCs with a mucosal tropism in blood. Nasal IgA and IgG antibody responses were lower in magnitude in SARS-CoV-2-naive subjects after two vaccine doses ConclusionThis study showed that a parenteral booster injection of a COVID-19 RNA vaccine promoted stronger mucosal immune responses in COVID-19 convalescent patients compared to SARS-CoV-2 naive subjects who had received a first vaccine dose.
