Scientists have found that men are more susceptible to the cytokine storm, while women have more robust T-cell activation.
In an article recently published in the journal Nature, researchers at Yale University found possible biological explanations of why men are more likely to develop severe Covid-19 than women.
The research focused on how the immune system responds to Sars-CoV-2 infection.
According to the World Health Organization (WHO), the pandemic has so far affected more than 24 million people worldwide, killing 832,000 of them – and 60% of the victims were men.
In addition, research in England found that men have twice the risk of dying from the disease than women.
In the new study, the researchers collected nasal, saliva, and blood samples from uninfected people, as well as from patients who tested positive for Covid-19.
The team looked at how the volunteers’ immune systems responded to infection with the new coronavirus and how the disease progressed over time, paying special attention to the differences between the immune systems of those who developed mild and severe conditions.
The scientists noted that men had higher levels of various types of inflammatory proteins called cytokines, including two known as IL-8 and IL-18.
These proteins are deployed as part of the body’s innate immune response. They are the first to respond to the presence of pathogens.
However, in severe Covid-19, an excessive accumulation of these proteins – the cytokine storm – causes fluid to accumulate in the lungs, depriving the body of oxygen and potentially leading to shock, tissue damage and multiple organ failure.
According to the researchers, men are more likely to experience a cytokine storm, making them more vulnerable to severe Covid-19.
In contrast, the researchers found that female patients had more robust T-cell activation, which can recognize invading viruses individually and eliminate them.
Among men (especially older ones), the T-cell response proved to be much weaker, leading to worse Covid-19 outcomes.
“We now have clear data suggesting that the immune landscape in COVID-19 patients is considerably different between the sexes and that these differences may underlie heightened disease susceptibility in men,” explained senior author Akiko Iwasaki. “Collectively, these data suggest we need different strategies to ensure that treatments and vaccines are equally effective for both women and men.”