‘Sex difference in immune response to COVID-19 decoded’

While previous research had shown that the severity of COVID-19 tends to be higher for men than for women, the underlying reasons for this discrepancy has remained unclear, according to the scientists, including those from Yale University in the US.

In the current study, they found that female patients mounted a more robust and sustained immune response via the body’s T cells than men. The researchers noted that T cells played an essential part in the immune system with their roles including the killing of infected cells.

According to the scientists, including Akiko Iwasaki from the Yale University School of Medicine, poor T cell responses correlated with a worse disease outcome in male patients.

“We found that a poor T cell response negatively correlated with patients’ age, and was associated with worse disease outcome in male patients, but not in female patients,” the researchers wrote in the study.

Compared with healthy control individuals, they said patients with COVID-19 were found to have elevated levels of innate immune cytokines and chemokines, which are signalling molecules involved in the recruitment of immune cells to sites of inflammation. However, the study noted that the levels of some of these molecules were higher in male patients than in female patients.

In female patients, the scientists said, higher levels of the cytokine molecules were associated with a worse disease response.

Based on the results, they said male patients may benefit from therapies that elevate T cell responses whereas female patients may benefit from therapies that dampen early innate immune responses.

However, the scientists caution that they were unable to rule out other underlying factors that may modify the risk of poor outcome in male and female patients with COVID-19.