The review provides data showing the nonspecific effect of preventive vaccines, such as pneumococcus, tuberculosis, and influenza, on the parameters of innate and adaptive immunity, which is reflected in a reduction of susceptibility not only to vaccine antigens, but also to other infectious pathogens. It is also discussed possible variants of immune mechanisms activation after the receiving a pneumococcal vaccine, especially conjugated polysaccharide vaccine, and their role in the interaction between the organism and the new SARS-CoV-2 coronavirus. Three variants of the nonspecific action of the vaccine are considered as the most probable: antigen mimicry, nonspecific activation and trained immunity.