Introduction:
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a causative agent of the ongoing pandemic. It can be transmitted among people via respiratory droplets generated while talking, coughing, or sneezing by an infected person. There is no known specific treatment or vaccine to prevent the coronavirus disease 2019 (COVID-19). The most effective way of limiting the spread of the virus is physical distancing combined with proper respiratory and hand hygiene. Many countries, including Poland, introduced restrictions in everyday life to control the pandemic. However, it has not been examined how these measures change the incidence of other infectious diseases.

Material and methods:
Data from biweekly reports on infectious diseases and poisonings published by National Institute of Public Health – National Institute of Hygiene (Narodowy Instytut Zdrowia Publicznego – Państwowy Zakład Higieny) were collected. The incidence of common and serious infectious diseases in the period 1.01.2020 to 15.05.2020 was evaluated and compared to the corresponding period from the year 2019.

Results:
A significant drop in the number of reported infectious diseases can be seen in the middle and at the end of March. These observations correlate with the time of introducing social distancing in Poland. The total number of reported cases, with the exception of pertussis, in the examined period is lower than in the year 2019.

Conclusions:
The results indicate that keeping physical distance and proper hygiene undoubtedly reduce the transmission of various infectious agents among people. However, there a long-term study is needed to observe trends in incidence of selected infectious diseases. It can be assumed that before the pandemic Polish society was not aware of the importance of social distancing and did not make use of hygiene as a method of infectious disease prevention. Further education should be continued and intensified.