Thread by @profshanecrotty

Our newest COVID-19 immunology work is online today at Cell! bit.ly/3mugShW

We aimed to better understand hospitalized COVID-19 cases by examining virus-specific immune responses all in the same people. SARS2-specific Helper T cells, killer T cells, and neutralizing antibodies.

(I.e., measure the adaptive immune response in acute COVID-19 cases with virus-specific tools.)

The three main findings are:
1) Coordinated adaptive immune responses (CD4, CD8, and antibodies together) were associated with reduced COVID-19 disease severity. The adaptive immune system fights the virus well when the 3 branches work together.

2) T cells appear to do the heavy lifting in controlling an active SARS-CoV-2 infection. Virus-specific helper T cells (CD4) and virus-specific killer T cells (CD8) both were significantly associated with lower COVID-19 disease severity.

3) Older people were much less likely to make a coordinated adaptive immune response. It appears that weak or absent T cell responses is a contributing risk factor for why older people are so much more susceptible to severe or fatal COVID-19.

The susceptibility of older people to severe COVID-19 may be, in part, because older people have fewer ’naive’ (inexperienced) T cells, which can make it harder for them to recognize and fight a new virus.
cell.com/cell/fulltext/…

We think this work fills an important piece of the COVID-19 puzzle. It looks like the adaptive immune responses are generally a good thing in the fight against this virus, and it is the absence of an adaptive immune response in some people that is a big problem in severe COVID-19

The problem of older people making T cell responses highlights issues to consider in treatment of COVID-19 cases, and the importance of vaccines electing strong immune responses in older people against COVID-19.

This was a big team effort by the Crotty lab, @SetteLab, @EOSaphire, @ljiresearch , and UCSD Infectious Disease clinicians!