Prior studies have established the existence of CD4+ T cells that cross-recognize SARS-CoV-2 and endemic common cold coronaviruses (CCCs).4, 5, 6, 7, 8, 9, 10, 11, 12 These cross-reactive T cells could have major impact on immunologic memory in the present COVID-19 pandemic and in possible zoonotic coronavirus outbreaks in the future. Here, CD4 is linked to COVID-19.