There is a male/female disparity in mortality due to COVID- 19: men are at greater risk than women of developing a serious form of the illness and dying. They account for about 60% of deaths: while the scientific community agrees on this figure, there is less agreement concerning the reasons why. Researchers differ in their opinions.
A study by T. Takahashi and his collaborators (at Yale University, New Haven, USA) suggested that this difference in mortality rates derives from a contrast in the way male and female immune systems operate. However, a team led by H. Shattuck-Heidorn at the University of Southern Maine, Portland, USA has cast doubts on this theory and proposed another hypothesis.
Takahashi and his collaborators analysed the differences in the immune systems of men and women in patients suffering from a moderate form of COVID-19. The researchers looked at the SARS-CoV-2 viral load, the antibody response to the virus and other immune markers such as cytokines (small proteins that enable communication between different elements within the immune system). The study investigated 98 patients hospitalised between the 18th of March and the 9th of May 2020. The team firstly showed that there was no significant difference in viral load between men and the women patients, whether in nasopharyngeal swabs (from 14 men and 14 women) or saliva samples (from 9 men and 12 women). Similarly, there was no difference in levels of antibodies in response to SARS-CoV-2.
However, the level of pro-inflammatory cytokines was higher in men, while levels of T lymphocytes were higher in women. As regards B lymphocytes, there was little difference between men and women. The T. Takahashi team was therefore able to claim different immune responses between men and women.