Human endogenous retroviruses (HERVs) are genome-resident relics of ancient infections. They comprise 8% of the human genome, and are activated by viral infections. Proteins like HERV-W and HERV-K accumulate following infections and have been causally connected to Multiple Sclerosis and Amyotrophic Lateral Sclerosis. Scientists have now observed that SARS-CoV2 infection also induces expression of specific HERV proteins. Prof. Claudia Matteucci discusses the role of HERVs and their tie to COVID19 diagnosis and potentially as central players in long COVID.