The genetic variability of each individual may lead to the identification of completely different genetic polymorphisms which are associated with a different sensitivity to infectious diseases in humans. Such genetic variability allows the immune system to respond differently to viral agents, therefore only a fraction of humans develop severe symptoms, as happened with SARS‐CoV‐2. Such knowledge is critical to enable the development of appropriate pharmacological solutions to prevent the consequences of insufficient immunity in dealing with serious viral diseases such as SARS‐CoV‐2. For instance, global epidemiological data show that male sex is a risk factor for the severe evolution of SARS‐CoV‐2 disease. Men, due to higher production of Testosterone (TLT), are more vulnerable than females. Women, due to greater expression of the TLR7 gene found on the X chromosome, a key innate immunity gene that encodes Toll‐like proteins, are able to synthesise more antiviral proteins and interferons in dendritic cells, resulting in a more robust immune system capable of preventing severe SARS‐CoV‐2 viral disease. This manuscript highlights how human genetic variability can lead to severe infectious symptoms in some individuals who must take appropriate prophylactic actions, such as vaccination, to prevent this.