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Immunological memory to SARS-CoV-2 at one-year post-infection

Published: September 14, 2021

The duration of immune memory to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is key for protecting against viral reinfection and provides insight into the design of vaccination strategies. A deep elucidation of immune memory to SARS-CoV-2 requires evaluation of its core elements, such as neutralizing antibodies (nAbs) and SARS-CoV-2-specific CD4+ T cells. However, how long nAbs and SARS-CoV-2-specific CD4+ T cells will persist needs to be further studied.

In a recent article in The Journal of Allergy and Clinical Immunology (JACI), Hou et al. evaluated the immune memory to SARS-CoV-2, including SARS-CoV-2-specific anti-receptor binding domain (RBD) and anti-nucleocapsid (N) antibodies, nAbs, and CD4+ T cell responses, in convalescent coronavirus disease 2019 (COVID-19) patients at one-year post-infection.

The positive rates of both anti-RBD and anti-N antibodies were 100% in convalescent patients. Accordingly, the prevalence of nAbs reached 93.59% in study participants, whereas the titres of nAbs were low. Notably, there was a significant correlation between nAb titres and anti-RBD levels. Moreover, SARS-CoV-2-specific T cells could be robustly maintained in convalescent patients, and the number of them was positively correlated with both nAb titres and anti-RBD levels. However, amplified SARS-CoV-2-specific CD4+ T cells mainly produced a single cytokine, accompanied with increased expression of exhaustion markers including PD-1, Tim-3, TIGIT, CTLA-4 and CD39, supporting the idea that the function of SARS-CoV-2-specific CD4+ T cells was exhausted.

The immune memory to SARS-CoV-2 in convalescent patients may persist for as long as one year. However, low nAb titers accompanied with exhausted function of SARS-CoV-2-specific CD4+ T cells support that a booster vaccination may be needed for preventing reinfection.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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