Crossreactive CD4+ T cells to SARS-CoV-2, thought to originate from immune responses to common cold coronaviruses (CCCs), have been reported in up to 80% of SARS-CoV-2-naive individuals. This led to the hypothesis that encounters with CCCs may provide a degree of cross-protective immune memory. Now, a study in Immunity shows that SARS-CoV-2-crossreactive CD4+ T cells can be detected in almost all individuals tested and that these cells generally have a low functional avidity. At the same time, the authors identified highly expanded populations of low-avidity CD4+ T cells as a hallmark of severe COVID-19. This challenges the idea of a protective function of crossreactive CD4+ T cells and even raises the possibility that these cells may contribute to the risk of developing severe COVID-19. However, given the correlative nature of the study, causal links remain to be verified.