Table 3.

Findings on T cellular immunity after infection.

Citation	T compartment
Tsang et al, 2022 (19)	CD4+ and CD8+ T cell responses persist over time and it is detectable even in the patient with the longest follow-up time at 219 days (who had undetectable anti-RBD IgG but persistent SARS-COV-2 specific CD4+ and CD8+ T-cell response).
Dowell et al, 2022 (20)	Cellular immune responses were detectable in 84% of children at least 6 months after infection. Compared to the cohort analysis at 6 months, T cell responses to spike were retained but somewhat reduced. Matched samples at 6 and 12 months were available for 5 of these children and were stable.
Kinoshita et al, 2021 (21)	There was no statistically significant difference between the affected patients and control groups regarding CD4+ T cell responses to actin or any of the SARS-CoV-2 proteins (membrane, envelope, nucleocapsid, or spike). Affected and control patients did not show appreciable CD8+ T cell responses. There was no significant difference in CD4+ T cell memory response for spike between affected and control patients with respect to naïve, central memory, effector memory, and terminal effector T cells.
Cotugno et al, 2021 (22)	There was a positive association between SARS-CoV-2-specific CD4 T cells and SARS-CoV2-specific IgG and Ab-neutralization activity.
Kaaijk et al, 2022 (23)	In 44% (8/18) of the infected children and 81% (17/21) of the infected adults, SARS-CoV-2-specific IFN-g + responses were detectable 10 months after symptom onset. In children at 10 months there was a 4-fold decline of S-SARS-CoV-2-specific IFN-g+ T cells at 10 months compared to frequencies at 3 weeks after infection; at 10 months there was no significant difference between exposed and unexposed children.
Cohen et al, 2021 (24)	IFNγ CD4+ and CD8+ T cell responses were significantly lower in SARS-CoV-2 infected children than in adults against the viral structural proteins, and in CD8+ T cells against ORF1ab proteins. Children’s T cells responses to polyclonal non-specific activation were also lower. T cell response in children is less antigen experienced and matured than adults. Memory T cell responses were smaller in children than in adults and this could be responsible of a weaker long-term memory response in children, with potential impact on reinfection.