The purpose of this work was a comparative study of the state of inflammatory reactions and the level of autoantibodies to neuroantigens in COVID-19 previously infected and vaccinated persons. People who have experienced a COVID-19 infection had an increased level of CRP, medium-mass molecules, in their blood serum. This indicates the persistence of a long-term inflammatory reaction after the infection. The level of autoantibodies to neuroproteins in blood sera was increased both in the groups of COVID-19 previously infected and vaccinated patients in comparison with persons who have not undergo the disease. This indicates the activation of humoral neuroautoimmune reactions, which can lead to the activation and development of progressive neurological complications in a remote period after infection. The level of anti-covid antibodies was 2-3 times higher in vaccinated than in COVID-19 previously infected persons, in the last group both high and low titers of antibodies were registered. This indirectly indicates possible re-infection and the need to vaccinate persons who already had experienced the infection. Subjects who have not suffered from COVID-19 show lower signs of intoxication, inflammation, and levels of neuroautoantibodies occurred if compare to other groups. In addition, the titer of specific anticovid antibodies was significantly low; this indicates a lack of humoral immunity to the COVID-19 virus. The reasons and mechanisms of such a “resistance” to infection are unclear and represent a certain scientific and practical interest for further study.