This study included the analysis of serological findings, PCR tests and vaccination data of 448 NZZJZ PGŽ patients. Average values of neutralizing antibody titers were calculated and compared in groups of subjects divided by age, sex, and previous exposure to viral antigens that was documented with positive PCR test, vaccination data, or both. Higher mean antibody values in the serum of female subjects and an increase in mean antibody values proportional to age were obtained. Over 7-fold higher mean serum antibodies were found in the serum of vaccinated versus unvaccinated subjects. Subjects who were vaccinated with at least one dose and also had a positive PCR test had 1.5 times higher average titer values than those who were only vaccinated. Unvaccinated individuals who had not recovered prior to the serological test had the lowest average antibody value obtained in the study. The highest mean antibody titer was obtained in subjects who received a booster dose of Comirnaty vaccine after previous primovaccination with Comirnaty vaccine. Statistically significant correlations were obtained between the titer of IgG neutralizing antibodies and the passed time from the last vaccine dose to the serological finding, as the passed time from the last vaccine dose to infection. Correlations were also made between IgG titer and the time passed between the first and second vaccine doses and the time between primovaccination and booster dose. The conclusions derived from the results and the analysis are: the humoral response triggered by vaccination is significantly more effective than the humoral response triggered by the disease and multiple antigen exposures lead to stronger humoral immune response. Also, the role of booster dose in stimulating humoral immune response is undisputable. The antibody titer decreases over time, and the lower the titer, the lower the immunity against SARS-CoV-2. It can also be concluded with high probability that the higher the time passed between the first and second dose of the vaccine, the higher the antibody titer.