Abstract : Background SARS-CoV-2 breakthrough infections after complete vaccination are increasing whereas their determinants remain uncharacterized. Methods We analyzed two cases of post-vaccination SARS-CoV-2 infections by α and β variants, respectively. For each participant both humoral (binding and neutralizing antibodies) and cellular (activation markers and cytokine expression) immune responses were characterized longitudinally. Results The first participant (P1) was infected by an α variant and displayed an extended and short period of viral excretion and symptom. Analysis of cellular and humoral response 72 h post-symptom onset revealed that P1 failed at developing neutralizing antibodies and a potent CD4 memory response (lack of SARS-CoV-2 specific CD4 + IL-2 + cells) and CD8 effector response (CD8 + IFNγ + cells). The second participant (P2) developed post-vaccination SARS-CoV-2 infection by a β variant, associated with a short period of viral excretion and symptoms. Despite displaying initially high levels and polyfunctional T cell responses, P2 lacked initial β-directed neutralizing antibodies. Both participants developed and/or increased their neutralization activity and cellular responses against all variants, namely, β and δ variants that lasts up to 3 months after breakthrough infection. Conclusions An analysis of cellular and humoral response suggests two possible mechanisms of breakthrough infection: a poor immune response to vaccine and viral evasion to neutralizing antibodies.
https://hal-pasteur.archives-ouvertes.fr/pasteur-03696752 Contributor : Isma ZianiConnect in order to contact the contributor Submitted on : Thursday, June 16, 2022 - 11:00:12 AM Last modification on : Saturday, June 25, 2022 - 3:44:19 AM
Floriane Gallais, Pierre Gantner, Delphine Planas, Morgane Solis, Timothée Bruel, et al.. Case Report: Evolution of Humoral and Cellular Immunity in Two COVID-19 Breakthrough Infections After BNT162b2 Vaccine. Frontiers in Immunology, Frontiers, 2022, 13, pp.790212. ⟨10.3389/fimmu.2022.790212⟩. ⟨pasteur-03696752⟩