AUTHOR=Jacobsen Henning , Cobos Jiménez Viviana , Sitaras Ioannis , Bar-Zeev Naor , Čičin-Šain Luka , Higdon Melissa M. , Deloria-Knoll Maria TITLE=Post-vaccination T cell immunity to omicron JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.944713 DOI=10.3389/fimmu.2022.944713 ISSN=1664-3224 ABSTRACT=

In late 2021, the omicron variant of SARS Coronavirus 2 (SARS-CoV-2) emerged and replaced the previously dominant delta strain. Effectiveness of COVID-19 vaccines against omicron has been challenging to estimate in clinical studies or is not available for all vaccines or populations of interest. T cell function can be predictive of vaccine longevity and effectiveness against disease, likely in a more robust way than antibody neutralization. In this mini review, we summarize the evidence on T cell immunity against omicron including effects of boosters, homologous versus heterologous regimens, hybrid immunity, memory responses and vaccine product. Overall, T cell reactivity in post-vaccine specimens is largely preserved against omicron, indicating that vaccines utilizing the parental antigen continue to be protective against disease caused by the omicron variant.