Covid-19 patients with a snippet of Neanderthal DNA that crossed into the human genome some 60,000 years ago run a higher risk of severe complications from the disease, researchers have reported.

People infected with the new coronavirus, for example, who carry the genetic coding bequeathed by our early human cousins are three times more likely to need mechanical ventilation, according to a study published Wednesday in Nature.

There are many reasons why some people with Covid-19 wind up in intensive care and other have only light symptoms, or none at all.

Advanced age, being a man, and pre-existing medical problems can all increase the odds of a serious outcome.