A single dose of the SARS-CoV-2 vaccine BNT162b2 elicits Fc-mediated antibody effector functions and T cell responses

Cell Host Microbe. 2021 Jul 14;29(7):1137-1150.e6. doi: 10.1016/j.chom.2021.06.001. Epub 2021 Jun 4.


While the standard regimen of the BNT162b2 mRNA vaccine for SARS-CoV-2 includes two doses administered 3 weeks apart, some public health authorities are spacing these doses, raising concerns about efficacy. However, data indicate that a single dose can be up to 90% effective starting 14 days post-administration. To assess the mechanisms contributing to protection, we analyzed humoral and T cell responses three weeks after a single BNT162b2 dose. We observed weak neutralizing activity elicited in SARS-CoV-2 naive individuals but strong anti-receptor binding domain and spike antibodies with Fc-mediated effector functions and cellular CD4+ T cell responses. In previously infected individuals, a single dose boosted all humoral and T cell responses, with strong correlations between T helper and antibody immunity. Our results highlight the potential role of Fc-mediated effector functions and T cell responses in vaccine efficacy. They also provide support for spacing doses to vaccinate more individuals in conditions of vaccine scarcity.

Keywords: ADCC; COVID-19; SARS-CoV-2; T cell responses; coronavirus; humoral responses; mRNA vaccine; neutralization; spike glycoproteins; variants.

Publication types

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

MeSH terms

  • Adult
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / chemistry
  • Antibodies, Viral / immunology*
  • BNT162 Vaccine
  • Betacoronavirus
  • COVID-19 / immunology*
  • COVID-19 / prevention & control
  • COVID-19 Vaccines / administration & dosage*
  • COVID-19 Vaccines / immunology*
  • Carrier Proteins
  • Female
  • Humans
  • Immunity
  • Immunoglobulin Fc Fragments
  • Male
  • Middle Aged
  • SARS-CoV-2 / immunology*
  • T-Lymphocytes / immunology*
  • Vaccination
  • Vaccines, Synthetic / immunology
  • Young Adult


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • Carrier Proteins
  • Immunoglobulin Fc Fragments
  • Vaccines, Synthetic
  • mRNA Vaccine
  • BNT162 Vaccine