By Andrew Carruthers, Editor-In-Chief.
Scientists are saying that women have stronger immune responses to infection, whilst men seem to suffer more when contracting the virus.
COVID-19 that originated in China is spreading fear like wildfire. Communities around the globe are gripped with panic, which in turn is creating all kinds of stressful shopping and clearing out of convenience store shelves in the hope that people will be prepared for the worst which they are envisioning is yet to come. Whilst the novel virus has spared one vulnerable group, namely children, it does appear to be a threat to middle-aged and older adults, particularly men.
A few weeks back, the Chinese Centre for Disease Control and Prevention published the largest analysis of coronavirus cases to date. Although men and women have been infected in almost equal numbers, researchers found that the death rate among men was around 2.8%, compared to that of women that are currently standing at 1.7%. These figures were drawn up from medical records, but may not fully reflect the scope of the outbreak. With that being said, the difference between men and women fatalities is not new news and is something that has be shown throughout the ages as diseases like the COVID-19 virus have shown throughout history, as men were also disproportionately affected during the SARS and MERS outbreaks. More women than men were infected by SARS in Hong Kong in 2003, but the death rate among men was 50% higher according to a study published in the Annals of Internal Medicine.
32% of men infected with Middle East Respiratory Syndrome (MERS) died, compared with 25.8% of women. Young adult men also died at higher rates than their female peers during the influenza epidemic of 1918.
So why are women stronger when it comes to fighting viruses like this?
There are a number of factors that might be working against men when it comes to fighting viruses such as the new COVID-19. Scientists believe that some are biological and others stem from lifestyle habits. When it comes to building immune responses to viruses and infections, men are just plain and simply the weaker sex.
According to Sabra Klein, a scientist who studies sex differences at the John Hopkins Bloomberg School of Public Health, “This is a pattern we’ve seen with many viral infections of the respiratory tract – men have worse outcomes”. “We’ve seen this with other viruses, women just fight them off better than men can.”
Women also produce stronger immune responses after vaccinations and have enhanced memory immune responses, which protect adults from pathogens they were exposed to as children. Dr Janine Clayton, director of the Office of Research on Women’s Health at the National Institute of Health says that, “There is something about the immune system in females that is simply more exuberant than males.” She also adds that “it does come at a price however, as women are more susceptible to autoimmune diseases like rheumatoid arthritis and lupus in which the immune system shifts into overdrive and attacks the body’s own organs and tissues.”
A scary statistic on the above mentioned flaw in the female immune system is that nearly 80% of all cases with autoimmune diseases are women. The reason why women have stronger immune responses aren’t entirely clear and research is still in its early stages.
One theory that would make sense as to why women have stronger immune responses is because it confers a survival advantage to their offspring, who gather antibodies from their mother’s breast milk to help ward off disease while infant’s immune systems are still developing.
An array of biological factors may be responsible, including the female sex hormone estrogen, which appears to play a huge role in immunity, and the fact that women carry two X chromosomes, which contain immune-related genes. Men, of course, only carry one.
Experiments in which mice were exposed to the SARS coronavirus found that male mice were more susceptible to infection than females, a disparity that increased with age. The male mice developed SARS at lower viral exposures, had a lower immune response and were also slower to clear the virus from their bodies. They suffered more lung damage and died at higher rates than their female counterparts.
Scientists also then went on to test further by blocking the estrogen in the infected females or removing their ovaries. When they did this the mice were more likely to die. In saying that, blocking the testosterone in the male mice made no difference at all, indicating that estrogen is a powerful player in the protective immune system.
How health behaviours differ between men and women.
China has the largest population of smokers on the planet, with 316 million people, accounting for one third of the world’s smokers and 40% of global tobacco consumption. But just over 2% of Chinese women smoke, compared with more than 50% of all men.
Chinese men also have higher rates of Type 2 Diabetes and High Blood Pressure than women, both of which increase the complications following infection with the Coronavirus. Rates of chronic obstructive pulmonary disease are almost twice as high among Chinese men as among women.
In the US, women are more proactive in seeking health care than men and some studies have shown that the generalisation applies to Chinese students at universities in the States as well. In unpublished studies, Chinese researchers have emphasised that patients whose diagnoses were delayed, or who had severe pneumonia when they were first diagnosed were at greater risk of dying.
Early detection is the key to survival in elderly men.
In a study that tested over 4,021 patients for the coronavirus, the results emphasised the importance of early detection of the virus, particularly in older men. The fact that men have been arriving at hospitals and clinics with a more advanced version of the virus, has meant that the possibility of fatality is much higher.
“Men seem to live with a false sense of security when it comes to the Coronavirus”, said Akiko Iwasaki, a professor of immunology at Yale University. Gathering and analyzing data about the new virus by sex is important both for the scientists studying it and for the general public, experts said.