Neutralizing SARS-CoV-2 Spike Antibodies against Omicron in Paired Samples after Two or Three Doses of mRNA Vaccine
Amanda K. Debes, Shaoming Xiao, Emily Egbert, Patrizio Caturegli, Avinash Gadala, Elizabeth Colantuoni, Ioannis Sitaras, Andrew Pekosz, Aaron M. Milstone
Abstract
This study found little to no neutralizing capability following a 2-dose mRNA vaccine series against the omicron variant, and neutralizing capacity to any variant strain tested was lost by 8-months post 2-dose series. However, the mRNA booster dose eliminated the immune escape observed by the Omicron variant, following the 2-dose series. Even more, the neutralizing titers were significantly higher for all variants post-boost, compared to the titers from the post-two-dose series. Our data are unique, using paired samples that eliminate potential confounders that may impact vaccine response. Notably, as seen after the primary two-dose vaccine series, total antibody levels did not correlate perfectly with variant neutralization activity, suggesting that simply testing titers as a measure of protection may not be a long-term solution. Therefore, it is important to reassess the utility of SARS-CoV-2 antibody testing, as current vaccine strain-based testing may not reliably detect reactive antibodies to Omicron or other variants of concern.