This is a summary, written by members of the CITF Secretariat, of:

Law JC, Koh WH, Budylowski P, Lin J, Yue F, Abe KT, Rathod B, Girard M, Li Z, Rini JM, Mubareka S, McGeer A, Chan AK, Gingras AC, Watts TH, A Ostrowski M. Systematic examination of antigen-specific recall T cell responses to SARS-CoV-2 versus influenza virus reveals a distinct inflammatory profile. J Immunol. 2021 Jan 1;206(1):37-50. doi: 10.4049/jimmunol.2001067.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

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While many agree on the importance of antibodies in SARS-CoV-2 infection, T cells have also taken the spotlight as a key contributor to immunity. Published in The Journal of Immunology, Drs. Tania Watts and Mario Ostrowski, from University of Toronto, found that SARS-CoV-2 recovered patients have strong T cell responses.


The authors examined the phenotype, activity and proliferation capacity of T cell after in vitro stimulation with either SARS-CoV-2 or seasonal influenza proteins in the same individuals. They used flow cytometry assays to characterize the T cells and measured cytokine production, using intracellular staining as well as multiplex assays. Most individuals showed a memory SARS-CoV-2 response from one type of T cell called CD4+T cell at 4-12 weeks after initial symptoms. Furthermore, people that recovered from COVID-19 had high levels of an inflammatory marker called tumor necrosis factor (TNF) and less of interferon-gamma (IFN-γ) in response to SARS-CoV-2 proteins than in response to seasonal influenza.

All in all, CD4+T cells had higher inflammatory characteristics and showed a weaker capacity to help trigger antibody production as a response to SARS-CoV-2, which suggests that they provide less protection than the response generated by the seasonal influenza virus.