Escape of SARS-CoV-2 Variant Omicron to Mucosal Immunity in Vaccinated Subjects

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. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Research reported in this publication was supported by grants from the Conseil Departemental des Alpes Maritimes, the Metropole Nice Cote dAzur. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the CPP Sud Mediterranee V ethics committee I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors