• Early Release - Cellular Immunity in #COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2–Specific IgG - Volume 27, Number 1—January 2021 - Emerging Infectious Diseases journal - CDC

    La plupart des sujets PCR #SARS-CoV-2 positifs qui ne développent pas d’anticorps (60 jours après l’installation des symptômes), développent une #immunité_cellulaire (tout comme les sujets qui fabriquent des #anticorps)

    We investigated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a group of convalescent, potential blood donors in Germany who had PCR-confirmed SARS-CoV-2 infection. Sixty days after onset of symptoms, 13/78 (17%) study participants had borderline or negative results to an ELISA detecting IgG against the S1 protein of SARS-CoV-2. We analyzed participants with PCR-confirmed infection who had strong antibody responses (ratio >3) as positive controls and participants without symptoms of SARS-CoV-2 infection and without household contact with infected patients as negative controls. Using interferon-γ ELISpot, we observed that 78% of PCR-positive volunteers with undetectable antibodies showed T cell immunity against SARS-CoV-2. We observed a similar frequency (80%) of T-cell immunity in convalescent donors with strong antibody responses but did not detect immunity in negative controls. We concluded that, in convalescent patients with undetectable SARS-CoV-2 IgG, immunity may be mediated through T cells.


    According to our data in volunteers with confirmed SARS-CoV-2 infection, it could be speculated that the majority of persons with undetectable systemic IgG may presumably be protected by specific T-cell immunity, which would be good news for the control of the pandemic.