Introduction
Neutralizing antibodies against omicron variants and subvariants, which
represents a strong correlate of protection from SARS-CoV-2 infection,
have been showed to significantly increase after bivalent booster
administration 1-4. Accumulating evidence suggests
that T cell response, i.e. helper CD4+ and cytotoxic CD8+ T cells, plays
a key role in the protection against severe disease 5.
In contrast to neutralizing antibodies, T cells are more resilient
against highly mutated emerging variants, with >80% of
epitopes conserved among T cells 5,6. Currently, the
long-term kinetics of the humoral and cellular immunity has been poorly
explored.