Drew Weissman of the Perelman School of Medicine responded to claims by CureVac executives that their COVID-19 vaccine’s poor results were due to the number of variants, among other factors. “Variants may account for some of their poor efficacy, but the modified [messenger RNA] vaccines have shown good efficacy against variants,” said Weissman.
https://www.washingtonpost.com/health/2021/06/30/curevac-covid-vaccine-results/ The Washington Post