Researchers have shown that certain immune cells, which are found in people previously exposed to common cold coronaviruses, enhance the body’s immune response to SARS-CoV-2, both during natural infection and following vaccination. The researchers also report that this ‘cross-reactive immunity’ decreases with age. This phenomenon may help to explain why older people are more susceptible to severe disease and why their vaccine-induced immunity is often weaker than that of young people.
