Variability in SARS-Cov-2 IgG Antibody Affinity To Omicron and Delta Variants in Convalescent and Community mRNA Vaccinated Individuals

The emergence of Omicron and Delta variants of SARS-CoV-2 has begun a number of discussions regarding breakthrough infection, waning immunity, need and timing for vaccine boosters and whether existing mRNA vaccines for the wildtype strain are adequate. Our work leverages a biosensor-based technique to evaluate the binding efficacy of SARS-CoV-2 S1 specific salivary antibodies to the Omicron and Delta variants using a cohort of mRNA vaccinated (n=109) and convalescent (n=19) subjects. We discovered a wide range of binding efficacies to the variant strains, with a mean reduction of 60.5%, 26.7%, and 14.7% in measurable signal to the Omicron strain and 13.4%, 2.4%, and -6.4% percent mean reduction to the Delta Variant for convalescent, Pfizer, and Moderna vaccinated groups respectively. This assay may be an important tool in determining susceptibility to infection or need for booster immunization as the pandemic evolves. Key PointsO_LIAMPERIAL assay developed to quantify salivary SARS-CoV-2 S1 IgG antibodies to Omicron and Delta variants C_LIO_LIThere was a reduction in affinity to both Delta and Omicron Variants C_LIO_LIThe reduction in affinity was more pronounced to Omicron than for Delta Variants C_LIO_LIThere was a significant difference between IgG affinities in Individuals vaccinated with Pfizer versus Moderna Vaccines C_LI