Add Thesis

Sex differences in COVID-19 infections

Written by M. Spahi

Paper category

Bachelor Thesis

Subject

Biology

Year

2020

Abstract

Bachelor Thesis: The outbreak of a new type of coronavirus called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is believed to be the cause of the 2019 Coronavirus Disease (COVID-19) reported in Wuhan, China on January 9, 2020 main reason. After the outbreak, the number of reported cases nationwide and globally increased rapidly (ECDC, 2020). An early report from Hubei Province provided the main findings of the outbreak in China, including observations and key findings. The report explains that SARS-CoV-2 is a zoonotic new type of coronavirus, which is highly contagious, spreads quickly, and can cause damage on a global scale (WHO, 2020). The more interesting finding is the gender difference between demographic characteristics, which indicates that there is a smaller male bias in the number of cases, and the death rate of males is higher than that of females. The report also shows that mortality increases with age (WHO, 2020). Other countries are now observing whether they are seeing the same pattern as the number of cases and deaths worldwide continues to increase. Previous studies have shown that during the 2003 SARS outbreak in Hong Kong, SARS (Severe Acute Respiratory Syndrome) and other coronaviruses affected men more than women (Karlberg et al., 2004). The Middle East Respiratory Syndrome (MERS) coronavirus is also known to have a significantly higher mortality rate for men than women (Jansen et al., 2015). Therefore, it is not surprising that this pattern seems to be followed in COVID-19 cases, as it is common in other coronaviruses. Many researchers have commented on this model and pointed out several possible theories. A proposed hypothesis explains that external factors such as different social norms in gender behavior may be responsible for these differences. Compared with women, men have a higher proportion of smoking and drinking, which is common worldwide. Such behaviors are related to comorbidities such as chronic lung disease and heart disease, which can worsen the outcome if contracted with COVID-19 disease (Purdie al, 2020). Another theory states that internal factors play a role and our sexes have different immune responses. Men and women are not only different in basic physiology, but also have a profound impact on their susceptibility and response to various diseases. Therefore, this shows that there are indeed gender differences between the sexes. However, most studies on gender differences are still poorly understood, and more needs to be discovered. In animal and human studies, the general conclusion that there are many more studies on men than women has limited our understanding of gender differences (Arnold, 2010). The onset of human puberty will lead to the secretion of hormones. Girls usually start at 9-10 years old, and boys start at 10-12 years old. This is also called puberty. Hormone levels before puberty are relatively low (Peper & Dahl, 2013). Sex hormones, such as testosterone, estrogen, and progesterone, fluctuate in different concentrations during the lifetime of different sexes, with lower levels in children and higher levels in later life. Male adult testosterone levels are relatively high, while lifelong progesterone levels are low. Adult women usually have high levels of estrogen and progesterone during childbearing age, and these levels increase significantly during pregnancy, including testosterone levels (Roberts et al., 2001). Then, women are considered to have drastically reduced estrogen, and men's testosterone levels should stabilize to 60 years of age, and then gradually decline (Ruggieri, 2018). Since the level of an individual's sex hormones changes with age, it should also have an impact on the immune response to sex hormones (Klein & Flanagan, 2016; Roberts et al. 2001). Hormone levels are important and can determine the outcome of infections, because testosterone is believed to have an immunosuppressive effect, while on the other hand, estrogen is believed to have an immune-boosting effect on the immune system (Taneja, 2018). This explanation makes the following assumptions: 1) Individuals infected with COVID-19 have no gender bias in terms of susceptibility or mortality to prepubertal infection. 2) Due to the immunosuppressive effect of testosterone and the protective effect of estrogen, there is male prejudice in terms of mortality and severity in disease-infected individuals of childbearing age. 3) In the post-birth age group, the mortality deviation of men should decrease again, while the male testosterone and female estrogen decrease. The purpose of this study is mainly to investigate the degree of gender differences in COVID-19 infection and to explore whether any differences are due to gender inherent factors that lead to gender bias in the susceptibility and mortality of individuals infected with COVID-19. Both external and internal factors may play a role in this pattern found in COVID-19 cases. However, this study will mainly focus on the internal factors that may determine the severity of this coronavirus and the sex of the outcome. The important characteristics of the individuals in this study are the sex and age of reported cases, intensive care cases, or SARS-CoV deaths-2 worldwide, because it is these two characteristics that may affect the susceptibility of the individual to infection and the severity of infection . Read Less