Longitudinal evaluation of SARS-CoV-2 T cell immunity over 2 years following vaccination and infection

Anna Karina Juhl*, Lisa Loksø Dietz*, Ole Schmeltz Søgaard, Joanne Reekie, Henrik Nielsen, Isik Somuncu Johansen, Thomas Benfield, Lothar Wiese, Nina Breinholt Stærke, Tomas Østergaard Jensen, Rikke Olesen, Kasper Iversen, Kamille Fogh, Jacob Bodilsen, Lone Wulff Madsen, Susan Olaf Lindvig, Dorthe Raben, Sidsel Dahl Andersen, Astrid Korning Hvidt, Signe Rode AndreasenEva Anna Marianne Baerends, Jens Lundgren, Lars Østergaard, Martin Tolstrup

*Corresponding author for this work


BACKGROUND: Within a year of the SARS-CoV-2 pandemic, vaccines inducing a robust humoral and cellular immune response were implemented worldwide. However, emergence of novel variants and waning vaccine induced immunity led to implementation of additional vaccine boosters.

METHODS: This prospective study evaluated the temporal profile of cellular and serological responses in a cohort of 639 SARS-CoV-2 vaccinated participants, of whom a large proportion experienced a SARS-CoV-2 infection. All participants were infection naïve at the time of their first vaccine dose. Proportions of SARS-CoV-2 Spike-specific T cells were determined after each vaccine dose using the Activation Induced Markers (AIM) assay, while levels of circulating SARS-CoV-2 antibodies were determined by the Meso Scale serology assay.

RESULTS: We found a significant increase in SARS-CoV-2 Spike-specific CD4+ and CD8+ T cell responses following the third dose of a SARS-CoV-2 mRNA vaccine as well as enhanced CD8+ T cell responses after the fourth dose. Further, increased age was associated with a poorer response. Finally, we observed that SARS-CoV-2 infection boosts both the cellular and humoral immune response, relative to vaccine-induced immunity alone.

CONCLUSION: Our findings highlight the boosting effect on T cell immunity of repeated vaccine administration. The combination of multiple vaccine doses and SARS-CoV-2 infections maintains population T cell immunity although with reduced levels in the elderly.

Original languageEnglish
JournalThe Journal of infectious diseases
Publication statusE-pub ahead of print - 30 Apr 2024


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