Why are elderly people more vulnerable to Covid even after vaccine boosters?
A new study offers some explanations. 1/
Individuals 70 y/o or older who received a primary 2-dose schedule with AZD1222 and booster 3rd dose with mRNA vaccine achieved significantly lower neutralizing antibody responses against SARS2 spike compared to those younger than 70 2/
One month after the booster neither the concentration of serum binding anti spike IgG antibody, nor the frequency of spike-specific B cells showed differences by age grouping. 3/
However, the impaired neutralization potency and breadth post-third dose in the elderly was associated with enrichment of circulating atypical spike-specific B cells expressing CD11c and FCRL5. 4/
Single cell RNA sequencing confirmed an expansion of TBX21-, ITGAX-expressing B cells in the elderly that enriched for B cell activation/receptor signalling pathway genes. 5/
Researchers also observed impaired T cell responses to SARS2 spike peptides in the elderly post-booster, both in terms of IFN gamma and IL2 secretion, as well as a decrease in T cell receptor signalling pathway genes. 6/
This expansion of ‘atypical B cells’ and impaired T cell responses may contribute to the generation of less affinity-matured antibodies, with lower neutralizing capacity post-third dose in the elderly. 7/