The size of a person’s ring finger has been linked to his danger of dying of COVID-19 in a examine, attributable to its potential hyperlinks to testosterone ranges. However, specialists not concerned within the analysis stated that whereas the work is attention-grabbing, extra analysis is required to verify the hyperlink between COVID-19 and the hormone, and nobody ought to really feel they’re protected from the coronavirus.
Men with longer ring fingers seem to have a decrease danger of dying from, or having, extreme COVID-19, in line with the authors of the examine revealed within the journal Early Human Development. They got here to their conclusion by what is named the digit ratio, which is regarded as a measure of publicity to testosterone within the womb. As more men have so far died of COVID-19 than women, some scientists have requested whether or not testosterone might play a task.
The digital ratio is calculated by dividing the size of the index finger, referred to as 2D, by the size of the ring finger, or 4D. Having a fourth finger longer than the second is believed to point increased publicity to hormones resembling testosterone within the womb. John Manning, professor of Evolutionary Psychology at Swansea University within the U.Okay. and first writer of the brand new examine, has spent years researching this matter.
To study the potential hyperlink between digit ratio and the severity of COVID-19, the researchers checked out current information from a web based survey on the common 2D:4D measures of 103,482 males and 83,366 ladies from 41 international locations. They additionally drew on COVID-19 case fatality price information—or the proportion of people that died from the quantity identified to have the illness—as reported by the World Health Organization on April 21, in addition to deaths by gender collated by Global Health 50/50 from 16 international locations.
The group discovered a hyperlink between excessive digit ratio, which suggests low publicity to testosterone within the womb, and extreme COVID-19 and excessive mortality charges in males. In different phrases, males with longer ring fingers appeared to have a decrease danger of dying or having extreme COVID-19.
It’s not clear what might clarify this affiliation. For occasion, typically, males have a much less strong immune response than females and are extra inclined to infectious illnesses, the authors defined. This has led to the concept that testosterone might negatively have an effect on the immune system, however on the identical time too robust a response might also result in a deadly overreaction, they stated.
The authors stated one other risk is that testosterone helps the coronavirus invade our cells, with what is named its spike protein binding to an enzyme in our our bodies referred to as ACE2. This might clarify why kids are much less more likely to fall severely ailing, as they’re pre-pubescent. But then again, as males age testosterone ranges lower, and ACE2 is expressed extra in females than males. “Paradoxically,” the authors wrote, the expression of ACE2 correlates negatively with dying from COVID-19.
“Our findings support an association between low prenatal testosterone (high 2D:4D) and high severity of COVID-19, and high mortality in males,” the group wrote, and high prenatal testosterone in males “may be protective of the serious effects of COVID-19.”
“A strong positive association between male 2D:4D and mortality may provide a biomarker for male COVID-19 susceptibility and identify those for whom it would be advisable to exercise social distancing,” they argued.
However, the group acknowledged the examine was restricted. For instance, the authors had been evaluating information throughout nations and charges of testing for COVID-19 can range tremendously, with some largely specializing in hospital sufferers who’re typically essentially the most severely ailing. This can skew case fatality charges between international locations.
“Therefore, we strongly advise that future investigations of associations of 2D:4D and COVID-19 severity consider patients. If there is a strong positive correlation with disease severity in men, the measurement of 2D:4D […] may be of prognostic use for the severity of COVID-19,” the authors wrote.
Experts not concerned within the analysis advised Newsweek the findings are attention-grabbing, however they’ve restricted use for tackling the pandemic.
Allan Pacey, professor of andrology on the U.Okay.’s University of Sheffield, advised Newsweek: “I don’t think anyone should consider themselves safer from COVID-19. Everyone should be following the relevant government guidance for their country and stay at home and/or practice social distancing when advised to do so.
“Moreover, everybody needs to be washing their fingers 6 to 10 instances per day, whatever the size of their ring finger.”
Pacey said the most obvious limitation of the study is that the analysis is based on country-level data on digit ratio rather than measures from people who died of COVID-19. However, he acknowledged this would present “moral challenges.”
Pacey also expressed concern that the analysis was done in the midst of the pandemic when final case numbers and death rates in each country are unknown.
“However, the authors of this paper needs to be applauded for his or her lateral pondering in arising with this evaluation. There could be one thing attention-grabbing right here about how our grownup immune system capabilities as a operate of prenatal intercourse hormone publicity. But that can want much more work to unpick,” he said.
Jeremy Rossman, honorary senior lecturer in virology at the U.K.’s University of Kent, told Newsweek this is the second study to link low testosterone levels in men and severe COVID-19 disease. The other paper, published in the journal Andrology, showed a correlation between testosterone levels in adult men and severe COVID-19 disease.
“It shouldn’t be thought that testosterone has a direct affect on COVID-19 illness, somewhat that it could have an effect on different components, resembling ACE2 expression ranges,” Rossman said. “This is a really new space of examine and additional analysis will likely be obligatory to verify the affiliation between testosterone ranges and COVID-19 illness, in addition to decide how testosterone ranges have an effect on the illness course.”
Since the pandemic started late last year, more than 5.5 million cases of COVID-19 have been confirmed worldwide, according to Johns Hopkins University. Some 350,509 people have died and more than 2.2 million are known to have recovered. The U.S. is the country with the most confirmed cases, as shown in the graph below by Statista.