Introduction and objective:
Prevention of Sars-CoV-2 infection aims primarily on actions to limit the spread of the virus. However, many people have taken steps to improve the functioning of the immune system. The aim of the study was to assess individual behaviours strengthening immunity during the COVID-19 pandemic.

Material and methods:
The study was conducted in 2020, in a group of 245 adult Poles: 208 females (84.9%) and 37 males (15.1%). The respondents completed an author constructed questionnaire via the Internet concerning physical activity, the frequency of consumption of selected products and dietary supplements used, as well as preventive behaviours in connection with the COVID-19 pandemic. Statistical analysis was carried out using the Statistica 13.0. The chi-square test was used to evaluate the differences between groups; the level of statistical significance was set at p<0.05.

A statistically significant increase was observed in the number of respondents (p <0.001) who were vaccinated against influenza in the current season (6.0% in 2019/20 vs. 28.0% in 2020/21). Respondents associated with health care were most frequently vaccinated (48% vs. 36% of students and 14% of those not related to the health sector), and the differences between groups in both analyzed periods were statistically significant. Probiotics were taken by 9.0% of respondents, 56.7% supplemented vitamin D3, and 38.0% vitamin C.

Prophylactic activities in the studied group focused on vaccinations and immediate supplementation of vitamins: D and C. The percentage of vaccinated persons was higher among those working in the health sector.

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