In order to assess the utility of PF4 non-binding vectors for vaccination purposes, the E1 genes of Ad5-ΔHVR1 and Ad34, as well as their PF4-binding relatives Ad5 and Ad11, were replaced by an expression cassette encoding the SARS-CoV-2 spike protein S1 domain to generate model COVID-19 vaccine vectors. This evidence concerns the gene PF4 and COVID-19.