Repeated exposure to subinfectious doses of sars-cov-2 may promote t cell immunity and protection against severe covid-19

Maria Laura De Angelis, Federica Francescangeli, Rachele Rossi, Alessandro Giuliani, Ruggero De Maria Marchiano*, Ann Zeuner

*Autore corrispondente per questo lavoro

Risultato della ricerca: Contributo in rivistaArticolo in rivista


Europe is experiencing a third wave of COVID-19 due to the spread of highly transmissible SARS-CoV-2 variants. A number of positive and negative factors constantly shape the rates of COVID-19 infections, hospitalization, and mortality. Among these factors, the rise in increasingly transmissible variants on one side and the effect of vaccinations on the other side create a picture deeply different from that of the first pandemic wave. Starting from the observation that in several European countries the number of COVID-19 infections in the second and third pandemic wave increased without a proportional rise in disease severity and mortality, we hypothesize the existence of an additional factor influencing SARS-CoV-2 dynamics. This factor consists of an immune defence against severe COVID-19, provided by SARS-CoV-2-specific T cells progressively developing upon natural exposure to low virus doses present in populated environments. As suggested by recent studies, low-dose viral particles entering the respiratory and intestinal tracts may be able to induce T cell memory in the absence of inflammation, potentially resulting in different degrees of immunization. In this scenario, non-pharmaceutical interventions would play a double role, one in the short term by reducing the detrimental spreading of SARS-CoV-2 particles, and one in the long term by allowing the development of a widespread (although heterogeneous and uncontrollable) form of immune protection.
Lingua originaleEnglish
pagine (da-a)961-N/A
Stato di pubblicazionePubblicato - 2021


  • COVID-19
  • Dose-Response Relationship, Immunologic
  • Environmental Exposure
  • Environmental exposure
  • Facial masking
  • Fomites
  • Humans
  • Immunologic Memory
  • Memory T cells
  • Protective immunity
  • SARS-CoV-2
  • T cell responses
  • T-Lymphocytes


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