IFNA17 and COVID-19: These autoantibodies against IFNα and IFNω blocked type I IFN signalling by impairing type I IFN ISG induction in vivo in the blood and upper respiratory tract during COVID-19, which could be rescued by exogenous IFNβ treatment in these patients (Supplementary Results 4, Extended Data Fig. 9c–h and Supplementary Fig. 13).