New research suggests they spend up to twice as long in hospital with Covid than those who still have a full head of hair.
They are also admitted to intensive care in higher numbers.
Scientists say men’s Covid vulnerability largely comes down to male sex hormones called androgens.
Men who are genetically more sensitive to androgens appear to be more likely to suffer severe Covid.
They are also more likely to have hair loss, called androgenetic alopecia, which affects around half of men over the age of 50.
The common condition also affects women in a different way, causing thinning at the crown of the head typically over the age of 65.
Androgenitic alopecia has previously been linked with several other conditions including heart disease and diabetes.
A team of US doctors measured men’s sensitivity to androgens by counting a chemical called CAG.
High levels indicate that a man is more likely to have hair loss.
Of 65 men hospitalised with the infection, those with high CAG levels had worse Covid outcomes in the 60 days following their hospitlisation.
They spent 47 days in hospital, on average, and 70.6 per cent were admitted to ICU.
For comparison, those with low CAG levels spent an average of 25 days in hospital, and 45.2 per cent were admitted to ICU.
Lead author Dr Andy Goren, chief medical officer at Applied Biology, Inc, Irvine, California, said CAG levels could be used to spot men at risk of ICU admission.
He said the study adds more evidence that variations in the AR gene and susceptibility to androgens are to some extent implicated in the severity of Covid infection.
Androgens are believed to act as a “gateway” to boost the coronavirus’s ability to attack cells.
It could also explain why men have died of Covid in higher numbers compared with women.
Dr Goren presented the findings to a virtual meeting of the European Academy of Dermatology and Venerology (EADV).
It comes after a study by the same team showed that bald men were up to twice as likely to be admitted to hospital in the first place.
The team reported in June that among men hospitalised with Covid in three Madrid hospitals, 79 per cent of had androgenetic alopecia.
This was dramatically disproportionate to the expected number of 31 to 53 percent in a similar age-matched population.
The link between baldness and severe symptoms was considered so strong the experts called for it to be considered a risk factor.
Professor Carlos Wambier of Brown University, who was part of the study, told The Telegraph in June: “We think androgens or male hormones are definitely the gateway for the virus to enter our cells.
“We really think that baldness is a perfect predictor of severity.”
Scientists have also found similar results in women who are losing their hair due to androgens.
