ABSTRACT
The novel coronavirus (SARS-CoV-2) and its variety that causes coronavirus disease 2019 (COVID-19) have had a great impact on human health and society since it was epidemic in 2019. The traditional immunological theories believe that human body resists the invasion of exogenous substances, such as different kinds of pathogenic microorganisms, through natural immunity and acquired immunity. We have greatly understood the underlying mechanisms of these two kinds of immunities, which are achieved through cellular and humoral immunity. Immune cells mainly include B and T cells. B cells produce specific antibodies and participate in the humoral immune response, while T cells have more extensive immune effects related to the cellular immune response. Therefore, such traditional immunological theories allow us habitually believe that the human body can resist the attack of virus as long as we have established the so-called normal cellular and humoral immune functions, however, in fact, this is not the case. The traditional ideas make us ignore the most critical, but simple and important defense system in our body to fight against the attack of foreign microorganisms, and that is the intracellular potassium ions (K+) and extracellular sodium ions (Na+), in particular, the intracellular potassium ions, called “K+/Na+ natural immune system”. The abnormality of this system, in particular, the intracellular relative deficiency of potassium ions, may have a very important relationship with the susceptibility and pathogenesis of the body to viral infection, and could explain a series of confusing phenomena that appeared during SARS-CoV-2 pandemic and provide new ideas for the prevention and treatment of COVID-19.