One dose of SARS-CoV-2 vaccine exponentially increases antibodies in individuals who have recovered from symptomatic COVID-19

J Clin Invest. 2021 Jun 15;131(12):e149154. doi: 10.1172/JCI149154.


BACKGROUNDThe COVID-19 vaccines currently in use require 2 doses to achieve optimal protection. Currently, there is no indication as to whether individuals who have been exposed to SARS-CoV-2 should be vaccinated, or whether they should receive 1 or 2 vaccine doses.METHODSWe tested the antibody response developed after administration of the Pfizer/BioNTech vaccine in 124 health care professionals, of whom 57 had a previous history of SARS-CoV-2 exposure with or without symptoms.RESULTSPostvaccine antibodies in SARS-CoV-2-exposed individuals increased exponentially within 5 to 18 days after the first dose compared to naive subjects (P < 0.0001). In a multivariate linear regression (LR) model we showed that the antibody response depended on the IgG prevaccine titer and on the exposure to SARS-CoV-2. In symptomatic SARS-CoV-2-exposed individuals, IgG reached a plateau after the second dose, and those who voluntarily refrained from receiving the second dose (n = 7) retained their antibody response. Gastrointestinal symptoms, muscle pain, and fever markedly positively correlated with increased IgG responses. By contrast, all asymptomatic/paucisymptomatic and unexposed individuals showed an important increase after the second dose.CONCLUSIONOne vaccine dose is sufficient in symptomatic SARS-CoV-2-exposed subjects to reach a high titer of antibodies, suggesting no need for a second dose, particularly in light of current vaccine shortage.TRIAL NCT04387929.FUNDINGDolce & Gabbana and the Italian Ministry of Health (Ricerca corrente).

Keywords: Adaptive immunity; Immunoglobulins; Immunology; Vaccines.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies, Viral* / blood
  • Antibodies, Viral* / immunology
  • Antibody Formation / drug effects*
  • BNT162 Vaccine
  • COVID-19 Vaccines / administration & dosage*
  • COVID-19 Vaccines / immunology
  • COVID-19* / blood
  • COVID-19* / immunology
  • Female
  • Humans
  • Male
  • Middle Aged
  • SARS-CoV-2* / immunology
  • SARS-CoV-2* / metabolism


  • Antibodies, Viral
  • COVID-19 Vaccines
  • BNT162 Vaccine

Associated data