The goal of this work was to present the data of the study of the peculiarities of the generation factors of humoral immunity in the response to the infection with the pandemic influenza A (HIN1) pdmO9 in patients with different epidemiological anamnesis. High ability of the influenza viruses to spread over closed communities and the transfer of the maternal antibodies to babies, including a pandemic strain of the influenza virus A (H1N1) pdm09, was confirmed. The results of this study showed that the immune response to the surface antigens of the influenza virus (hemagglutinin and neuraminidase) was formed during the natural infection with the pandemic strains of the influenza A (H1N1) pdm09 in more than a half of the cases simultaneously.