Men with longer ring fingers are at a lower risk of dying from Covid-19 and are more likely to have mild symptoms, scientists claim.
A study found in countries where men have short ring fingers, their Covid-19 death rate was up to a third higher.
Ring finger length is determined by how much testosterone a fetus is exposed while growing in the womb, the researchers explained in their published paper.
The more testosterone a man is exposed in a uterus, the longer their ring finger will be believed to be.
It is the same hormone that is believed to be protective against severe Covid-19 by increasing ACE-2 receptors in the body.
ACE-2 receptors are believed to be protective against the progression of Covid-19 when someone catches the coronavirus, thereby reducing symptoms.
A recent study found that men with low testosterone levels are twice as likely to die as men with higher levels.
Men with longer ring fingers have a lower risk of dying from Covid-19 and are more likely to have mild symptoms, a study claims (stock)
Researchers found that in countries where the right digit ratio was smaller, including Malaysia, Russia and Mexico, the death rate was lower (left side)
Men die from the coronavirus earlier than women, but scientists have not been able to pinpoint exactly why this is so.
Hypotheses include that men wash their hands less often, may not seek medical attention, have a genetically impaired immune system compared to women, or have more underlying health problems that make them more vulnerable.
Another theory is that testosterone implies how the immune system works in men, but not women, and lower-level men are at risk.
Scientists led by Swansea University added to the theory that men with low testosterone levels are more at risk for Covid-19 than other men.
They looked at data from 200,000 people in 41 countries where researchers had measured their finger length.
The index finger (second) and ring finger were measured to the millimeter. Divide the first measurement by the second measurement to get the ratio.
WHY ARE MEN MORE AT RISK ON COVID-19?
Several studies have reported a higher death rate in men than in women.
Until more research helps to conclude why, there are different schools of thought.
The difference between adult men and women is largely due to behaviors such as drinking alcohol, smoking, and unhealthy eating.
Dr. James Gill, a general practitioner and honorary clinical teacher at Warwick Medical School, said the theories start from the assumption that men don’t just care for their bodies, with increased smoking, alcohol consumption, obesity and other harmful health behaviors.
These would put men at a higher risk of health problems – which have been confirmed to be detrimental to the COVID-19 results.
The gender difference in smoking is especially evident in some countries, such as China, where 50 percent of men smoke, compared to five percent among women.
Dr. However, Gill said, “Although smoking is a plausible factor, worldwide, in different cultures, where the number of smokers varies, we still see the persistent difference in mortality between men and women.
“While we don’t have a definitive answer as to why there is a difference between how men and women respond immunologically to a COVID19 infection, it is currently a reasonable assumption that there will be significant interplay between biology and environmental facts. ‘
The slight increase in boys infected with coronavirus compared to girls may not be due to behaviors such as smoking.
Philip Goulder FMedSci, professor of immunology at the Department of Pediatrics, Oxford University, explained how men and women have genetically different immune responses, which would be present from birth.
He said: “It is increasingly recognized that there are substantial differences in the immune system between men and women and that they have significant implications for the outcome of a wide range of infectious diseases.
Several factors contribute to this, but this includes the fact that females have two X chromosomes compared to one in males, and a number of critical immune genes are located on the X chromosome.
‘The protein with which viruses such as coronavirus are detected, in particular, is encoded on the X chromosome. As a result, this protein is twice as high in many immune cells in women as in men, thus enhancing the immune response to coronavirus in women. ‘
This effect can be seen in how the body responds to vaccines.
The lifelong immune response to vaccines and infections is typically more aggressive and effective in women than in men, Professor Goulder said.
The smaller the ratio, the longer the ring finger is. The country with the smallest average ratio was Malaysia, with 0.976.
The higher the ratio, the shorter the ring finger. Bulgaria has the highest ratio at 0.99.
Researchers found that in countries where the ratio was smaller, including Malaysia, Russia and Mexico, the mortality rate was lower.
And in countries where the ratio was higher, including the UK, Bulgaria and Spain, the mortality rate was higher.
The finding was more significant when looking at the right hand than the left and was not found in women.
The top 10 countries with the longest ring fingers had an average death rate of 3.1 compared to the 10 countries with the shortest ring fingers, with an average death rate of 5.
The death rate is the number of people who contract the coronavirus and eventually die from the disease.
However, it is not considered to be completely accurate as it relies on testing strategies that identify all cases, and this varies from country to country.
Swansea University lead researcher Professor John Manning said this could provide Australia, New Zealand, Austria and East Asian countries, where male ring fingers are longer, a “biological benefit”, the sun reports.
In fact, he said, “Our findings may be that men with long ring fingers will experience mild symptoms and get back to work.”
The researchers said finger length is an indicator of the amount of testosterone a fetus was exposed to during growth.
Manning says Manning: “The theory is that someone with high prenatal testosterone – and a long ring finger – has more ACE2.
“These concentrations are large enough to fight the virus.”
Cell receptors called ACE-2, which cover the surfaces of cells, are what the coronavirus attaches to infect our healthy cells.
It is thought that the more of these receptors you have, the more entry points for the virus.
However, ACE-2 receptors are believed to limit disease progression once the coronavirus is in the body.
The virus is known to cause lung damage by decreasing the number of ACE-2 receptors once in the body.
Therefore, it appears that people with high ACE-2 levels may in fact be protected from the severity of the disease.
Professor Manning wrote in his paper, “The ACE-2 gene is more strongly expressed in women than in men.
These associations suggest a negative correlation between ACE-2 expression and Covid-19 fatality. The down-regulation of ACE-2 may therefore be associated with a poor prognosis of Covid-19.
“Research suggests that testosterone in men (and estrogen in women) up-regulates ACE-2.”
The paper concludes, “A strong positive association between male 2D: 4D (digit ratio) and mortality may provide a biomarker for the sensitivity of male Covid-19 and identify for whom it would be advisable to distance socially.”
A recent study found that men with low testosterone levels who contract Covid-19 are at a much higher risk of dying from the virus, a study found.
Samples from the 45 Covid-19 patients in a German hospital were tested for 12 hormones, including testosterone and dihydrotestosterone.
Professor Gülsah Gabriel of the Leibniz Institute for Experimental Virology in Hamburg, who was involved in the study, told MailOnline: “The majority of male Covid-19 patients had low testosterone levels.
Of those male Covid-19 patients who died, the majority also had low testosterone levels.
“For example, low testosterone levels in men appear to be a risk factor for serious and even fatal disease outcomes in men after infection with so-called ‘cytokine-inducing’ respiratory viruses.”
Testosterone is known to help regulate the body’s immune response, but when a man has low testosterone levels, the immune system is not controlled and can become confused after infection.
This leads to a so-called cytokine storm that occurs when the immune system gets out of hand while trying to kill the pathogen.
A cytokine storm eventually begins to damage the body itself and, if left unchecked, can be deadly.
Of the male Covid-19 patients sent to the ICU in the German hospital, more than two thirds (68.6 percent) registered low testosterone levels.
In contrast, the majority of female patients (60 percent) had elevated testosterone levels.
Although low testosterone levels cannot control the immune response in men, the study found that higher testosterone levels in female Covid-19 patients were associated with a more significant inflammatory response.