Why men are more vulnerable to COVID-19 than women

Recent research published in the European Heart Journal suggested that men have a higher amount of angiotensin-converting enzyme 2 (ACE2) in their plasma, which is likely why they are more vulnerable to COVID-19. The study was led by Dr Adriaan Voor, Professor of Cardiology at the University Medical Center Groningen (UMCG) in The Netherlands. [caption id=“attachment_8330851” align=“alignleft” width=“380”]  Representational image. Image by Mircea Iancu from Pixabay.[/caption] ACE2 is also a receptor present on the surface of healthy cells. SARS-CoV-2, the causative agent of COVID-19, uses this receptor to enter inside cells. ACE2 receptors are present in abundance in the lungs, heart, kidneys and testes. Early investigations have reported that even though COVID-19 affects all age groups and genders, older people and those with chronic diseases (especially men) are more likely to become severe cases once they contract the virus. Overall, about 58.1% of all COVID-19 patients have been men and 41.9% have been women and 70% of all patients that died in Italy were older men.

The study

For the study, Dr Voor and his team measured the amount of ACE2 in the blood of 1,485 men and 537 women with heart failure - ACE2 blood concentration increases in case of heart failure. The results of the study were validated in another 1,123 men and 575 women with heart failure. The study concluded that men have a higher concentration of ACE2 in their blood, which did not occur due to the use of ACE2 inhibitors or ACE2 receptor blockers. The latter indicated that ACE2 inhibitors or ACE2 receptor blockers do not increase ACE2 in COVID-19 patients as previously thought. It was further added that the high levels of the ACE2 were present in testes and the specific regulation of ACE2 protein formation in testes may explain why coronavirus flourishes in men and makes them more susceptible to the disease.

Other possible causes

This is not the first study that says that higher expression of ACE2 in testes may be the reason behind the susceptibility of men to COVID-19. A preprint, non-peer reviewed study done on 68 subjects, also suggested the same earlier in April. A study published in The Western Journal of Emergency Medicine indicated that the presence of only one X chromosome in men makes them more likely to get infections. Humans have two sex chromosomes, women have two X chromosomes while men have an X and a Y. A majority of immunity-determining genes are present on the X chromosome. This is also why women are more likely to get autoimmune diseases. Additionally, more men tend to smoke than women and some experts say that this may be the reason behind their susceptibility to COVID-19. More smokers are seen to have COVID-19 in China, Italy and the USA. High testosterone levels are also considered to be contributors to severe COVID-19 in men due to specific receptors that testosterone promotes the formation of. However, low testosterone in older age may weaken respiratory muscles and, in clinical studies, older men with chronic heart failure have shown increased oxygen consumption on getting testosterone therapy. For more information, read our article on Severe vs mild COVID-19. Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.