Case Report: Evolution of Humoral and Cellular Immunity in Two COVID-19 Breakthrough Infections After BNT162b2 Vaccine

Abstract

BackgroundSARS-CoV-2 breakthrough infections after complete vaccination are increasing whereas their determinants remain uncharacterized.MethodsWe 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.ResultsThe 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.ConclusionsAn 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.

Molecular evolution of the SARS-CoV-2 omicron BA.2 variant in kidney transplant recipients with prolonged viral shedding

“…The authors forecast these variants’ potential ability to evade immune responses. Research investigating the occurrence of prolonged SARS-CoV-2 shedding from the upper respiratory tract has detected that this phenomenon is common 2 and associated with the emergence of de novo mutations in the viral genome. Here, we describe the emergence of SARS-CoV-2 mutations in a cohort of kidney transplant recipients (KTRs) who experienced prolonged viral shedding despite being treated with anti-SARS-CoV-2 monoclonal antibodies.…”