Robust Neutralizing Antibody Levels Detected after Either SARS-CoV-2 Vaccination or One Year after Infection

Viruses. 2021 Oct 5;13(10):2003. doi: 10.3390/v13102003.


Humoral immunity after infection or after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been attributed a key part in mitigating the further transmission of the virus. In this study, we used a commercial anti-Spike immunoglobulin G (S-IgG) assay and developed a cell culture-based neutralization assay to understand the longitudinal course of neutralizing antibodies in both SARS-CoV2 infected or vaccinated individuals. We show that even more than one year after infection, about 78% of observed study participants remained seropositive concerning S-IgG antibodies. In addition, the serum of the individuals had stable neutralization capacity in a neutralization assay against a SARS-CoV-2 patient isolate from March 2020. We also examined volunteers after either homologous BNT162b2 prime-boost vaccination or heterologous AZD1222 prime/mRNA-based booster vaccination. Both the heterologous and the homologous vaccination regimens induced higher levels of neutralizing antibodies in healthy subjects when compared to subjects after a mild infection, showing the high effectiveness of available vaccines. In addition, we could demonstrate the reliability of S-IgG levels in predicting neutralization capacity, with 94.8% of seropositive samples showing a neutralization titer of ≥10, making it a viable yet cheap and easy-to-determine surrogate parameter for neutralization capacity.

Keywords: COVID-19; SARS-CoV-2; antibodies; immunity; neutralization; serology; vaccination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Animals
  • Antibodies, Neutralizing / blood*
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / blood*
  • Antibodies, Viral / immunology
  • BNT162 Vaccine
  • COVID-19 / immunology
  • COVID-19 Vaccines / immunology*
  • Cell Line
  • ChAdOx1 nCoV-19
  • Chlorocebus aethiops
  • Humans
  • Immunity, Humoral / immunology
  • Immunization, Secondary
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Middle Aged
  • Neutralization Tests
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / isolation & purification
  • Spike Glycoprotein, Coronavirus / immunology
  • Vaccination
  • Vero Cells


  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • Immunoglobulin G
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • ChAdOx1 nCoV-19
  • BNT162 Vaccine