Blame the Neanderthals?

It is obvious that there are multifactorial influences on human susceptibility, as well as responses to, a Covid-19 infection. Those commonly cited include age (older people being more endangered than younger counterparts); gender (males appear more at risk than females); having an 'underlying medical condition' (such as a heart defect, diabetes or asthma); having a particular occupation that increases exposure (such as being a front-line health worker or a bus driver); being overweight (people with a high BMI have poorer outcomes) and belonging to a particular ethnic group (BAME folk seem to be particularly at risk). It goes without saying that many of these factors tend to coalesce in particular individuals. There have been a number of suggestions about the involvement of genetic factors. A recent Swedish study looked at the genetics of patients who were extremely ill as a result of a Covid-19 infection (https://www.theguardian.com/science/2020/sep/30/neanderthal-genes-increase-risk-of-serious-covid-19-study-claims). They found 'risk genes' that, amongst other things, altered the immune response and were involved in the mechanism used by the virus to infect cells. What was more remarkable was that they found that this strand of DNA corresponded very closely to a sequence of genes extracted from a Neanderthal skeleton found in Croatia. This is a strand that many modern humans have inherited as a result of their ancestors breeding with Neanderthals (it's not, however, the only portion of the Neanderthal genome that can be found in some modern humans). The sequence (which must have been beneficial in earlier times) is carried by around 17% of Europeans and 50% of South Asians (one of the vulnerable ethnic groups). The authors of the study estimate that possession of these genes has led to 100,000 additional deaths in the Covid-19 pandemic. It's probably not as simple as this but it does represent a line of necessary investigation.