The consequences of Sars-Cov-2 infection differ markedly between individuals, and while many people recover from the infection with asymptomatic or mild symptoms, others experience severe and severe illness.
Led by Jean-Laurent Casanova from Rockefeller and Paris Universities, two new studies of the international consortium, including Dr. Kaya Bilgüvar, published in the Journal of Science Immunology on August 19, 2021 (1, 2), shed an important light on this variability.
The findings of the studies reveal that genetic and immunological disorders affecting immunity due to type 1 interferon, which constitute the first immunological barrier against viral infections, can explain more than 20% of severe Covid-19 cases.
 Autoantibodies neutralizing type I IFNs are present in ~ 4% of uninfected individuals over 70 years and account for ~ 20% of COVID-19 deaths, P. Bastard et al., Science Immunology, 2021
 X-linked recessive TLR7 deficiency in 1% of men under 60 years with life-threatening COVID-19, T. Asano et al, Science Immunology, 2021.