Abstract
Background
Within a year of the severe acute respiratory syndrome coronavirus 2 (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 marker 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 messenger RNA vaccine as well as enhanced CD8+ T-cell responses after the fourth dose. Furthermore, 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.
Conclusions
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.
Within a year of the severe acute respiratory syndrome coronavirus 2 (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 marker 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 messenger RNA vaccine as well as enhanced CD8+ T-cell responses after the fourth dose. Furthermore, 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.
Conclusions
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 language | English |
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Journal | The Journal of Infectious Diseases |
Volume | 230 |
Issue number | 3 |
Pages (from-to) | e605-e615 |
Number of pages | 11 |
ISSN | 0022-1899 |
DOIs | |
Publication status | Published - 2024 |