Immunology: Sex differences in immune responses to SARS-CoV-2

Differences in the immune response of male and female patients with COVID-19 are outlined in a paper published in Nature. The findings may help to guide a sex-based approach to the treatment and care for male and female patients.

Research has shown that the severity of COVID-19 tends to be higher for men than for women, but the underlying reasons for this discrepancy have been unclear. To learn more, Akiko Iwasaki and colleagues assessed 98 patients (aged 18 years or over; on average, patients were 61–64 years of age) admitted to the Yale New Haven Hospital in the United States with mild to moderate disease who had confirmed positive tests for SARS-CoV-2 infection. They found that female patients mounted a more robust and sustained T cell response than male patients. T cells are an essential part of the immune system, and their roles include the killing of infected cells. Poor T cell responses were shown to correlate with a worse disease outcome in male patients.

Patients with COVID-19 were found to have elevated levels of innate immune cytokines and chemokines — signalling molecules that are involved in the recruitment of immune cells to sites of inflammation — compared with healthy control individuals. However, the levels of some of these factors were higher in male patients than in female patients. In female patients, higher innate immune cytokine levels were associated with a worse disease response. The results indicate that 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 authors caution that they were not able to rule out other underlying factors that may modify the risk of poor outcome in male and female patients with COVID-19.