The emergence of SARS-CoV-2 lineages and associated antibody responses among asymptomatic individuals in a large university community

Abstract

SARS-CoV-2 (CoV2) infected, asymptomatic individuals are an important contributor to COVID transmission. CoV2-specific immunoglobulin (Ig)—as generated by the immune system following natural infection or vaccination—has helped limit CoV2 transmission from asymptomatic individuals to more susceptible populations. The emergence of new Omicron lineages with extensive Spike and Nucleocapsid (N) mutations threatens our reliance on natural and vaccine-initiated Ig responses to limit COVID transmission; therefore, it is important to understand the relationships between CoV2 lineage emergence, CoV2-specific Ig levels, and their cross-neutralization capacity in asymptomatic individuals. Here, we describe the relationships between COVID incidence and CoV2 viral load, lineage, and CoV2-specific Ig levels (IgM, IgA, and IgG) in the saliva of asymptomatic individuals between Jan 2021 and May 2022. These data were generated as part of a large university COVID monitoring program and demonstrate that COVID incidence among asymptomatic individuals occurred in waves which mirrored those in surrounding regions, with saliva CoV2 viral loads becoming progressively higher until vaccine requirements were established. Among the unvaccinated, infection with each CoV2 lineage (pre-Omicron) resulted in Spike-specific IgM, IgA, and IgG responses, with Spike-specific IgG increasing significantly post-infection and being more pronounced than N-specific IgG responses. Among the vaccinated, saliva from those with breakthrough Delta infections had Spike-specific IgG levels that were comparable to those who were uninfected; their capacity to inhibit Spike function, however, was diminished relative to those who were uninfected. The Ohio State University