Immunology: BNT162b2 vaccine can neutralize three SARS-CoV-2 variants

The Pfizer-BioNTech COVID-19 vaccine (BNT162b2) is shown to neutralize SARS-CoV-2 with the N501Y and E484K mutations in a study of sera from 20 vaccine recipients published in Nature Medicine.

New strains of SARS-CoV-2 that appeared in the United Kingdom and South Africa share the same N501Y mutation. A separate South African strain has an E484K mutation. These mutations are located in viral spike protein, and could potentially increase the affinity of the viral spike for the ACE2 receptor to which SARS-CoV-2 is known to bind. The N501Y mutation also seems to expand the range of hosts the virus can infect to include mice. Understanding whether the vaccines currently developed for SARS-CoV-2 also provide protection against these mutations is an urgent priority.

Pei-Yong Shi, Philip Dormitzer and colleagues engineered combinations of mutations found in these circulating variants and tested a panel of human sera from 20 participants—from their previously published clinical trial of the BNT162b2 vaccine—obtained 2 or 4 weeks after immunization with two doses of BNT162b2 spaced three weeks apart. Each serum was tested for neutralization of the non-mutant strain of SARS-CoV-2 as well as the mutant viruses. The authors found evidence of neutralization of the mutant viruses by the sera panel, with slight variation: neutralization against the E484K mutation was slightly lower than neutralization against the N501Y mutation.

The authors conclude that the ongoing evolution of SARS-CoV-2 calls for continuous monitoring of vaccine efficacy for emerging strains.