Skip to main content

Neutralization of N501Y mutant SARS-CoV-2 by BNT162b2 vaccine-elicited sera

Our take —

The study, available as a preprint and thus not yet peer reviewed, showed that Pfizer/BioNTech vaccine-induced antibodies are reactive against an important mutation in the two newly reported SARS-CoV-2 variants. While these results are encouraging, testing the efficacy against the whole set of mutations in these new variants is essential. In addition, continuous monitoring of vaccinated individuals will ultimately determine the degree and longevity of protection the vaccine provides against these variants.

Study design


Study population and setting

The study included samples from 20 participants from the Pfizer/ BioNTech’s phase3 SARS-CoV-2 clinical trial. The sera were collected from participants at 2 and 4 weeks after the second standard dose of the vaccine. The authors tested the ability of these sera to prevent the infection of cultured cells with SARS-CoV-2 with and without a mutation at the amino acid 501, a common mutation in the receptor binding domain between the newly described UK and South-African variants.

Summary of Main Findings

The study found that there was no reduction in the neutralization activity of the sera from the previously vaccinated participants against a mutant virus.

Study Strengths

Recently, new SARS-CoV-2 genetic variants were reported initially in UK and South Africa and subsequently were detected in many other countries. These variants are of public health interest because they are associated with recent increases in cases. As these variants have mutations in the spike protein, the target of many vaccines including those developed by Pfizer/BioNTech and Moderna, they raised the concerns about the efficacy of the current vaccines against these variants. This study tested the ability of the vaccine-induced antibodies to neutralize SARS-CoV-2 viral particles carrying one of the mutations that changes the amino acid number 501 from asparagine to tyrosine. This mutation was found in both the UK and South African variants and was shown to increase the binding of the virus to its receptor. The study included 20 participants and the sera from these participants were simultaneously tested against both the mutant and wildtype viruses.


The study is relatively small, and included only one mutation in the viral spike protein and not the full set of changes seen in the new variants. The sera tested was also taken soon after the second dose of the vaccine and may not reflect the neutralization potential later after vaccination.

Value added

This study suggests that the currently used Pfizer/BioNTech COVID19 vaccine is effective against one of the common mutations in two newly described SARS-CoV-2 variants.

This review was posted on: 22 January 2021