Mumps in Poland in 2021.

Introduction: Mumps is a contagious viral disease occurring mainly in children, the source of infection being the sick/infected person. Since 2003, vaccination against mumps has been mandatory in Poland, performed according to a two-dose schedule. As part of the Public Health Immunization Program (PSO), the MMR combination vaccine (against measles, mumps and rubella) is used for the entire population of children.

Objectives: The aim of this study was to evaluate epidemiological indicators of mumps in Poland in 2021 compared to previous years, taking into account the impact of the COVID-19 pandemic.

Material and methods: The analysis of the epidemiological situation of mumps in Poland in 2021 was based on the interpretation of data from the bulletin , "Infectious diseases and poisonings in Poland in 2021" and , "Immunization in Poland in 2021".

Results: 484 cases of mumps were registered in Poland in 2021. The total incidence was 1.3 per 100,000 residents, which was lower than in 2020. The highest incidence of 1.8 per 100,000 residents was registered in Pomorskie Province, and the lowest incidence of 0.7 in Lower Silesia Province. The highest incidence (6.4/100 thousand) was recorded in children aged 0-4 and 5-9. The incidence rate for men (1.4/100,000) was higher than for women (1.1). In 2021, there were 9 patients hospitalized due to mumps, this was more than in 2020.

Conclusions: The decrease in the number of cases of mumps in 2021 remained related to the ongoing pandemic - the restrictions introduced during the pandemic period led to a decrease in the number of cases not only of COVID-19, but also of other diseases spread by the droplet route, including mumps. The number of registered cases based on the reports of diagnosing physicians may be underestimating the actual number of cases due to the continued difficult access of patients to primary care physicians.