Abstract
BackgroundInformation regarding the heterologous prime-boost COVID vaccination has been fully elucidated. The study aimed to evaluate both humoral, cellular immunity and cross-reactivity against variants after heterologous vaccination. MethodsWe recruited healthcare workers previously primed with Oxford/AstraZeneca ChAdOx1-S vaccines and boosted with Moderna mRNA-1273 vaccine boost to evaluate the immunological response. Assay used: anti-spike RBD antibody, surrogate virus neutralizing antibody and interferon-γ release assay. ResultsAll participants exhibited higher humoral and cellular immune response after the booster regardless of prior antibody level, but those with higher antibody level demonstrated stronger booster response, especially against omicron BA.1 and BA.2 variants. The pre-booster IFN-γ release by CD4+ T cells correlates with post-booster neutralizing antibody against BA.1 and BA.2 variant after adjustment with age and gender. ConclusionsA heterologous mRNA boost is highly immunogenic. The pre-existing neutralizing antibody level and CD4+ T cells response correlates with post-booster neutralization reactivity against the Omicron variant.
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