COVID-19 high-risk groups: Why the immune system is less effective at fighting the virus

Older people and people with underlying medical conditions are at particular risk of severe COVID-19. Researchers have discovered one possible reason for this vulnerability. While these risk groups produce greater quantities of an important type of immune cell known as 'T-helper cells', their T-helper cells show impaired function. This 'molecular brake' on the immune system could serve as a potential new treatment target in patients with severe COVID-19.