claim: a booster dose enhances immunogenicity of the covid-19 vaccine candidate chadox1 ncov-19 in aged mice
evidence_1: furthermore, we report that a second dose enhances the immune response to this vaccine in aged mice, indicating that a primeboost strategy may be a rational approach to enhance immunogenicity in older persons.", "we find that a single dose of this vaccine induces cellular and humoral immunity in aged mice, but at a reduced magnitude than in younger adult mice.")