Research
Hormonal
Thymic involution with age leads to a reduced output of naive T cells, resulting in a narrowed T-cell receptor repertoire and impaired ability to mount new immune responses to novel antigens.
As you age, your thymus gland shrinks (involution), producing fewer new naive T cells. This means your immune system has a harder time recognizing and fighting new infections or responding to new vaccines because it lacks the diverse 'tools' (naive T cells) to handle novel threats.
GoodSupportsHIGH confidence
The reduction in the frequency of naïve T cells, together with the increasing proportion of terminally differentiated T lymphocytes and the decrease in cells expressing T-cell receptor rearrangement excision circles... have long been hallmarks of immune aging.
Why this rating
Based on extensive human and animal studies cited.
Source
Aging of the immune system: Focus on inflammation and vaccination
Marcello Pinti et al. · European Journal of Immunology · 2016
DOI 10.1002/eji.201546178
narrative_reviewCited 443×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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