Key Points
T cell responses against Omicron are well preserved after COVID-19 or mRNA vaccination.
Recipients of two mRNA vaccine doses only have lower T cell responses.
Abstract
Several studies have demonstrated that the SARS-CoV-2 variant-of-concern B.1.1.529 (Omicron) exhibits a high degree of escape from Ab neutralization. Therefore, it is critical to determine how well the second line of adaptive immunity, T cell memory, performs against Omicron. To this purpose, we analyzed a human cohort (n = 327 subjects) of two- or three-dose mRNA vaccine recipients and COVID-19 postinfection subjects. We report that T cell responses against Omicron were largely preserved. IFN-γ–producing T cell responses remained equivalent to the response against the ancestral strain (WA1/2020), with some (∼20%) loss in IL-2 single or IL-2+IFN-γ+ polyfunctional responses. Three-dose vaccinated participants had similar responses to Omicron relative to post–COVID-19 participants and exhibited responses significantly higher than those receiving two mRNA vaccine doses. These results provide further evidence that a three-dose vaccine regimen benefits the induction of optimal functional T cell immune memory.
Footnotes
This work was supported in part by U.S. Public Health Service Grant R37 AG020719 and the Bowman Professorship in Medical Sciences (to J.N.-Ž.), as well as by Centers for Disease Control and Prevention HEROES Project Award 75D30120C08379 (to J.L.B.).
The online version of this article contains supplemental material.
- Received March 8, 2022.
- Accepted March 30, 2022.
- Copyright © 2022 by The American Association of Immunologists, Inc.
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