Thread by @RajeevJayadevan

T cell response in Astrazeneca vaccine recipients.

Study of 296 people aged 18 to 85 years.

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There has been plenty of discussion about antibodies following vaccination but studies of T cell response are uncommon. This paper gives details.

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science.org/doi/10.1126/sc…

Optimal T cell response was detected - that is CD4 Th1 and CD8 with a high degree of polyfunctionality, covering a broad range of spike protein epitopes.

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This increased T cell breadth will help fight variants. In other words, a few viral mutations here or there will not make a difference to these T cells.

This means the virus will continue to be hunted down even if it modified its appearance to gain entry into the body.

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The authors found no difference in the breadth or depth of T cell response among people who had a four-week gap or a 12 week gap between doses.

The second dose increased the polyfunctionality of these T cells.

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Rather than quantity, the quality of T cells improves with the second dose. T cell response of the right type, depth and breadth are crucial in preventing severe disease from COVID-19.

Studies of people who died from COVID-19 had shown minimal or absent CD4 CD8 response.

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Also, those who had CD4 and CD8 T cells present in blood, developed less severe disease. This shows that antibodies alone are not enough to fight prevent severe disease.

Two doses of vaccine are required to produce the right numbers as well as the right quality of T cells.

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This means that the vaccine, given in 2 doses, induces an optimal T cell response covering multiple viral epitopes spanning the length of the spike protein.

This implies that they can continue to outsmart the virus and prevent severe disease, in spite of future mutations.

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