SARS-CoV-2-specific T cell memory is long-lasting in the majority of convalsecent COVID-19 individuals

Abstract

An unaddressed key question in the current coronavirus disease 2019 (COVID-19) pandemic is the duration of immunity for which specific T cell responses against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are an indispensable element. Being situated in Wuhan where the pandemic initiated enables us to conduct the longest analyses of memory T cell responses against SARS-CoV-2 in COVID-19 convalescent individuals (CIs). Magnitude and breadth of SARS-CoV-2 memory CD4 and CD8 T cell responses were heterogeneous between patients but robust responses could be detected up to 9 months post disease onset in most CIs. Loss of memory CD4 and CD8 T cell responses were observed in only 16.13% and 25.81% of CIs, respectively. Thus, the overall magnitude and breadth of memory CD4 and CD8 T cell responses were quite stable and not inversely correlated with the time from disease onset. Interestingly, the only significant decrease in the response was found for memory CD4 T cells in the first 6-month post COVID-19 disease onset. Longitudinal analyses revealed that the kinetics of SARS-CoV-2 memory CD4 and CD8 T cell responses were quite heterogenous between patients. Loss of memory CD4 T cell responses was observed more frequently in asymptomatic cases than after symptomatic COVID-19. Interestingly, the few CIs in which SARS-CoV-2-specific IgG responses disappeared showed more durable memory CD4 T cell responses than CIs who remained IgG-positive for month. Collectively, we provide the first comprehensive characterization of the long-term memory T cell response in CIs, suggesting that SARS-CoV-2-specific T cell immunity is long-lasting in the majority of individuals.

One Year after Mild COVID-19: The Majority of Patients Maintain Specific Immunity, But One in Four Still Suffer from Long-Term Symptoms

“…This assumption is supported by an observation from Wuhan, China, where the majority of COVID-19 patients also showed a decrease in T-cells directed against SARS-CoV-2 in a biphasic manner. Comparable to our study, the Chinese study found a loss of specific CD8 T-cells in 26% of convalescents and a loss of specific CD4 helper cells in only 16% after 9 months [32].…”

Utility of Different Surrogate Enzyme-Linked Immunosorbent Assays (sELISAs) for Detection of SARS-CoV-2 Neutralizing Antibodies

“…In addition to a humoral mediated immune response, T cell-mediated immune response plays a role in SARS-CoV-2 infection and the specific cellular immunity may be more stable and longer lasting than humoral immunity [ 38 , 39 ]. This is particularly of interest regarding the immunity of recovered patients with low or no detectable neutralizing antibodies [ 40 ].…”

Long-term and short-term immunity to SARS-CoV-2: why it matters

“…We have confirmed the presence of SARS-CoV-2 specific CD4 T cells in recovered patients in the ADAPT Study at St Vincent's Hospital, Sydney, using the OX40 assay, but like other studies, have found that about half of healthy non-COVD-19 controls had responses to pools of peptides from the full SARS-CoV-2 spike protein sequence, presumably cross-reacting with endemic coronaviruses 54 . SARS-CoV-2 specific memory CD4 and CD8 T cells were still present in recovered patients at 9 months after symptom onset in one study 55 , and at 6-8 months in another study, with an apparent halflife of only 3-5 months 56 .…”