1. Repeated Exposure to Subinfectious Doses of SARS-CoV-2 May Promote T Cell Immunity and Protection against Severe COVID-19
- Author
-
Ruggero De Maria, Federica Francescangeli, Rachele Rossi, Ann Zeuner, Maria Laura De Angelis, and Alessandro Giuliani
- Subjects
0301 basic medicine ,Opinion ,T cell ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,T-Lymphocytes ,Dose-Response Relationship, Immunologic ,Inflammation ,Microbiology ,Virus ,Memory T cells ,Dose-Response Relationship ,03 medical and health sciences ,protective immunity ,0302 clinical medicine ,Immunologic ,Settore MED/04 - PATOLOGIA GENERALE ,Virology ,Pandemic ,medicine ,Humans ,030212 general & internal medicine ,fomites ,business.industry ,SARS-CoV-2 ,COVID-19 ,facial masking ,Environmental exposure ,Environmental Exposure ,QR1-502 ,Vaccination ,030104 developmental biology ,Infectious Diseases ,medicine.anatomical_structure ,Immunization ,T cell responses ,Immunology ,medicine.symptom ,business ,Immunologic Memory - Abstract
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.
- Published
- 2021