Women are more likely to develop a stronger immune response to the novel coronavirus than men, a new study has found, offering a possible explanation for the more serious illness of COVID-19 often seen in men.
Results published in the journal Nature on Wednesday noted that globally, men account for about 60% of deaths linked to COVID-19 – the highly infectious respiratory disease caused by the new coronavirus.
“What we found is that men and women indeed develop different types of immune responses to COVID-19,” Akiko Iwasaki said, the lead author of the study and a professor at Yale University in the United States.
The immunity specialist said that “these differences may underlie increased susceptibility to disease in men.”
The researchers took nasal, saliva and blood samples from uninfected control subjects and patients with the disease who were treated at Yale Hospital New Haven in the United States.
They found that the women had developed a more robust immune response involving T lymphocytes, which are a type of white blood cell that can recognize viruses and kill them. This was the case even in older women, according to the study.
In contrast, older men had lower T cell activity – the older they were, the weaker the response.
Overall, men also produced more cytokines, which are inflammatory proteins that form another part of the body’s natural immune defense.
However, severe cases of COVID-19 have been linked to what is called a “cytokine storm”, when the immune system goes into overdrive, which is harmful and potentially fatal.
Men who showed high levels early on were more likely to have a severe case of the disease, while women who also had significant cytokine levels seemed to fare worse, according to the study.
According to the authors, this could imply that men and women need different treatments.
For men, for example, “we should improve their T-cell responses with vaccines,” Iwasaki said, while women might receive treatment to dampen the cytokine response.
Since the start of the pandemic, most countries have reported a higher number of deaths from the novel coronavirus in men than in women.
Experts have offered a number of possible explanations for this trend.
“One theory is that men are more likely to develop unhealthy habits, which are associated with the development of chronic diseases,” wrote Dr. Sara Kayat in an article for Al Jazeera.
The presence of the extra X chromosome that women have as well as hormones are other possible reasons, she said.
The peer-reviewed Yale study has some limitations, however. The sample size was relatively small, with 98 patients in total. The average age of the patients was also high, at around 60 years.
Commenting on the research, Eleanor Riley, a professor at the University of Edinburgh, said some of the discrepancies noted in the study are likely caused by differences in age or BMI, which measures body fat. TGender differences disappear once these other factors are taken into account.
She said treatments would be better if they were tailored individually, rather than just defined based on gender.