Natural exposure or infection may prevent recurrent episodes of severe COVID-19

See "Robust T cell immunity in convalescent individuals with asymptomatic or mild COVID-19" from the journal Cell. By Takuya Sekine , André Perez-Potti, Olga Rivera-Ballesteros, Hans-Gustaf Ljunggren , Soo Aleman and Marcus Buggert. 

"Highlights

• 1. Acute phase SARS-CoV-2-specific T cells display an activated cytotoxic phenotype
• 2. Broad and polyfunctional SARS-CoV-2-specific T cell responses in convalescent phase
• 3. Detection of SARS-CoV-2-specific T cell responses also in seronegative individuals

Summary

SARS-CoV-2-specific memory T cells will likely prove critical for long-term immune protection against COVID-19. We here systematically mapped the functional and phenotypic landscape of SARS-CoV-2-specific T cell responses in unexposed individuals, 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 exposed family members and convalescent individuals with a history of asymptomatic and mild COVID-19. Our collective dataset shows that SARS-CoV-2 elicits robust, broad and highly functional memory T cell responses, suggesting that natural exposure or infection may prevent recurrent episodes of severe COVID-19."