Low Serum Levels of Interferon Alpha in COVID-19 Patients Are Associated with Older Age.

Innate immune response, especially type 1 interferon (IFN) response is considered to play a substantial role in the outcome of SARS-CoV-2 infection. A reduced and delayed IFN response has been associated with progression to severe COVID-19. In this study, we investigated levels of circulating IFNα and serum neutralizing activity in COVID-19 patients admitted to the intensive care unit. We found a significant association of levels of IFNα with age ( p = 0.007). This association has also been observed in a cohort of COVID-19 outpatients with mild infection ( p = 0.02). The impact of senescence on IFN response can explain the higher susceptibility of the elderly to severe COVID-19.