Last year, researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig and at Karolinska Institutet in Sweden showed that the major genetic risk factor for severe Covid-19 is inherited from Neandertals. Now the same researchers show, in a study published in PNAS, that Neandertals also contributed a protective variant. Half of all people outside Africa carry a Neandertal gene variant that reduces the risk of needing intensive care for Covid-19 by 20 percent.