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. 2024 Mar 4;12(3):270.
doi: 10.3390/vaccines12030270.

Prolonged SARS-CoV-2 T Cell Responses in a Vaccinated COVID-19-Naive Population

Vassiliki C Pitiriga  1 , Myrto Papamentzelopoulou  2 , Kanella E Konstantinakou  3 , Irene V Vasileiou  3 , Alexandros D Konstantinidis  3 , Natalia I Spyrou  3 , Athanasios Tsakris  1
Affiliations

Prolonged SARS-CoV-2 T Cell Responses in a Vaccinated COVID-19-Naive Population

Vassiliki C Pitiriga et al. Vaccines (Basel). .

Abstract

Introduction: Exploring T cell response duration is pivotal for understanding immune protection evolution in natural SARS-CoV-2 infections. The objective of the present study was to analyze the T cell immune response over time in individuals who were both vaccinated and COVID-19-naive and had undetectable levels of SARS-CoV-2 IgG antibodies at the time of testing.

Methods: We performed a retrospective descriptive analysis using data extracted from the electronic medical records of consecutive adult individuals who underwent COVID-19 immunity screening at a private healthcare center from September 2021 to September 2022. The study participants were divided into three groups according to the post-vaccination time period, as follows: group A (up to 3 months), group B (3-6 months), and group C (>6 months). T cell response was evaluated using the IGRA methodology T-SPOT®.COVID.

Results: Of the total number of subjects (n = 165), 60/165 (36.4%) had been vaccinated in the last 3 months (group A), 57/165 (34.5%) between 3 and 6 months (group B), and 48/165 (29.1%) at least 6 months prior to the examination day (group C). T cell positivity was reported in 33/60 (55.0%) of group A, 45/57 (78.9%) of group B, and 36/48 (75%) of group C (p < 0.007). No statistically significant differences were revealed in the spot-forming cell (SFC) count among groups, with mean SFC counts of 75.96 for group A, 89.92 for group B, and 83.58 for group C (Kruskal-Wallis test, p = 0.278).

Conclusions: Our findings suggest that cellular immunity following SARS-CoV-2 vaccination may endure for at least six months, even in the presence of declining or absent IgG antibody levels.

Keywords: COVID-19; SARS-CoV-2; T cell immunity; cellular immunity; vaccination; vaccines.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Quantitative T-SPOT analysis of T cell responses to the SARS-CoV-2 S antigen at the respective ages of the total participants. Quantitative T-SPOT results are represented by dots; linear regression model curve estimation for the entire participant cohort.
Figure 2
Figure 2
Kinetics (in days) of T cell response with quantitative T-SPOT results represented by dots in figures: linear regression model curve estimation for the entire participant cohort.
Figure 3
Figure 3
Kinetics (in days) of T cell response with quantitative T-SPOT results represented by dots in figures: linear regression model curve estimation for group A.
Figure 4
Figure 4
Kinetics (in days) of T cell response with quantitative T-SPOT results represented by dots in figures: linear regression model curve estimation for group B.
Figure 5
Figure 5
Kinetics (in days) of T cell response with quantitative T-SPOT results represented by dots in figures: linear regression model curve estimation for group C.
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