PLoS ONE (Jan 2022)

Lower probability and shorter duration of infections after COVID-19 vaccine correlate with anti-SARS-CoV-2 circulating IgGs

  • Chiara Ronchini,
  • Sara Gandini,
  • Sebastiano Pasqualato,
  • Luca Mazzarella,
  • Federica Facciotti,
  • Marina Mapelli,
  • IEO Covid Team,
  • Gianmaria Frige’,
  • Rita Passerini,
  • Luca Pase,
  • Silvio Capizzi,
  • Fabrizio Mastrilli,
  • Roberto Orecchia,
  • Gioacchino Natoli,
  • Pier Giuseppe Pelicci

Journal volume & issue
Vol. 17, no. 1

Abstract

Read online

The correlation between immune responses and protection from SARS-CoV-2 infections and its duration remains unclear. We performed a sanitary surveillance at the European Institute of Oncology (IEO) in Milan over a 17 months period. Pre-vaccination, in 1,493 participants, we scored 266 infections (17.8%) and 8 possible reinfections (3%). Post-vaccination, we identified 30 infections in 2,029 vaccinated individuals (1.5%). We report that the probability of infection post-vaccination is i) significantly lower compared to natural infection, ii) associated with a significantly shorter median duration of infection than that of first infection and reinfection, iii) anticorrelated with circulating antibody levels.