Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19

Sekine, Takuya; Perez-Potti, André; Rivera-Ballesteros, Olga; Strålin, Kristoffer; Gorin, Jean-Baptiste; Olsson, Annika; Llewellyn-Lacey, Sian; Kamal, Habiba; Bogdanovic, Gordana; Muschiol, Sandra; Wullimann, David J.; Kammann, Tobias; Emgård, Johanna; Parrot, Tiphaine; Folkesson, Elin; Rooyackers, Olav; Eriksson, Lars I.; Sönnerborg, Anders; Allander, Tobias; Albert, Jan; Nielsen, Morten; Klingström, Jonas; Gredmark-Russ, Sara; Björkström, Niklas K.; Sandberg, Johan K.; Price, David A.; Ljunggren, Hans-Gustaf; Aleman, Soo; Buggert, Marcus

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. We systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in a large cohort of unexposed individuals as well as exposed family members and individuals with acute or convalescent COVID-19. Acute phase SARS-CoV-2-specific T cells displayed a highly activated cytotoxic phenotype that correlated with various clinical markers of disease severity, whereas convalescent phase SARS-CoV-2-specific T cells were polyfunctional and displayed a stem-like memory phenotype. Importantly, SARS-CoV-2-specific T cells were detectable in antibody-seronegative family members and individuals with a history of asymptomatic or mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits robust memory T cell responses akin to those observed in the context of successful vaccines, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19 also in seronegative individuals.