Serum Neutralizing Activity of mRNA-1273 against SARS-CoV-2 Variants

J Virol. 2021 Nov 9;95(23):e0131321. doi: 10.1128/JVI.01313-21. Epub 2021 Sep 22.


The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has led to growing concerns over increased transmissibility and the ability of some variants to partially escape immunity. Sera from participants immunized on a prime-boost schedule with the mRNA-1273 COVID-19 vaccine were tested for neutralizing activity against several SARS-CoV-2 variants, including variants of concern (VOCs) and variants of interest (VOIs), compared to neutralization of the wild-type SARS-CoV-2 virus (designated D614G). Results showed minimal, statistically nonsignificant effects on neutralization titers against the B.1.1.7 (Alpha) variant (1.2-fold reduction compared with D614G); other VOCs, such as B.1.351 (Beta, including B.1.351-v1, B.1.351-v2, and B.1.351-v3), P.1 (Gamma), and B.1.617.2 (Delta), showed significantly decreased neutralization titers ranging from 2.1-fold to 8.4-fold reductions compared with D614G, although all remained susceptible to mRNA-1273-elicited serum neutralization. IMPORTANCE In light of multiple variants of SARS-CoV-2 that have been documented globally during the COVID-19 pandemic, it remains important to continually assess the ability of currently available vaccines to confer protection against newly emerging variants. Data presented herein indicate that immunization with the mRNA-1273 COVID-19 vaccine produces neutralizing antibodies against key emerging variants tested, including variants of concern and variants of interest. While the serum neutralization elicited by mRNA-1273 against most variants tested was reduced compared with that against the wild-type virus, the level of neutralization is still expected to be protective. Such data are crucial to inform ongoing and future vaccination strategies to combat COVID-19.

Keywords: COVID-19; SARS-CoV-2 variants of concern; mRNA-1273; neutralization.

Publication types

  • Clinical Trial, Phase I
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 2019-nCoV Vaccine mRNA-1273
  • Adult
  • Antibodies, Neutralizing / immunology*
  • Antibodies, Viral / immunology
  • COVID-19 / immunology*
  • COVID-19 / prevention & control*
  • COVID-19 Vaccines / immunology*
  • Female
  • Humans
  • Male
  • Mutation
  • Neutralization Tests
  • Pandemics / prevention & control*
  • SARS-CoV-2 / immunology*
  • Spike Glycoprotein, Coronavirus / immunology*
  • Vaccination


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • Spike Glycoprotein, Coronavirus
  • 2019-nCoV Vaccine mRNA-1273