Spike-Directed Vaccination Elicits Robust Spike-Specific T cell Responses Including to Mutant Strains

While most studies describing COVID-19 vaccine responses have focused on antibodies, there is increasing evidence that T cells play a critical role. Here we evaluated T cell responses in seronegative donors before and after vaccination to define responses to SARS-CoV-2 reference strain, as well as to mutations in the variant strains B.1.1.7 and B.1.351. We observed enhanced T cell responses to reference and variant Spike strains post vaccination.