Rapidly spreading variants of SARS-CoV-2 that have arisen in the United Kingdom and South Africa share the spike N501Y substitution, which is of particular concern because it is located in the viral receptor binding site for cell entry and increases binding to the receptor. We generated isogenic N501 and Y501 SARS-CoV-2. Twenty human sera from the mRNA-based vaccine BNT162b2 trial exhibited equivalent neutralizing titers to the N501 and Y501 viruses.