What is it about?

We have shown that multiple types of SARS-CoV-2-specific T helper cells (Th2, Th17) are highly active in the first 10 weeks after COVID-19 and then disappear completely. However, SARS-CoV-2-specific Th1 cells remain stably active for years after infection.

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Why is it important?

T cells limit the severity of viral infections. We show that there are two distinct phases of T cell reactivity in patients recovering from COVID-19. The initial but transient accumulation of several types of T helper cells may imply particularly efficacious protection against SARS-CoV-2 in the first months after COVID-19. The finding that reactive Th1 cells remained functional for years challenges the view that T cell-mediated protection against COVID-19 might decline over time. Instead, our results suggest that all infected patients harbor stably reactive Th1 cells after SARS-CoV-2 infection and that these protective cells do not disappear or decline over time.


The stable presence of reactive Th1 cells after COVID-19 might explain, in part, why reinfection only rarely gives rise to severe disease. The persistent Th1 response may thus offer protection against severe infection despite the waning or disappearance of antibodies. The follow-up time of our study was inherently short and additional studies are required to define the long-term duration of T cell reactivity against SARS-CoV-2.

Kristoffer Hellstrand
University of Gothenburg

Read the Original

This page is a summary of: Transient and durable T cell reactivity after COVID-19, Proceedings of the National Academy of Sciences, July 2022, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2203659119.
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