Background: There has been a decline in vaccine-related confidence in Ukraine over the past few years, resulting in high rates of infectious diseases. Due to the arrival of a large number of refugees in Poland following the outbreak of war in Ukraine in February 2022, the risk of infectious diseases in Poland among children and adults has increased. The present study aimed to analyze the relationship between parents' knowledge of the epidemiological situation of infectious diseases in Poland and Ukraine and socio-demographic factors and their attitudes towards vaccination., Material and Methods: A cross-sectional survey study was designed. Data were collected through an online questionnaire between November 2022 and January 2023, where the inclusion criteria was having a child under 18 years of age. Study participants' stratification was based on responses to seven knowledge questions; those who answered all questions correctly were allocated to group 1, and the others to group 2 for further analysis., Results: A total of 547 parents were included. Their median age was 34 years [IQR: 31-39]. There were 233 (42.60%) participants who answered all the knowledge questions correctly. Respondents from group 1 were older ( p = 0.033), were more likely to be in favor of recommended vaccination ( p = 0.040), to be vaccinated with four doses against SARS-CoV-2 ( p = 0.014), to have their children vaccinated against SARS-CoV-2 ( p < 0.001), and to believe that the influx of migrants from Ukraine would increase the incidence rate of infectious diseases in Poland in the future ( p < 0.001). They also declared awareness of the impact of migration on the epidemiological situation in Poland ( p < 0.001) more often. According to the logistic regression model, older parents (OR = 1.31, p = 0.029), those who were willing to receive additional vaccinations due to migration (OR = 4.29, p = 0.003), those who were aware of the impact of migration on the epidemiological situation (OR = 2.38, p < 0.001), and those who believed that migration would have affected the incidence rate of infectious diseases in Poland (OR = 2.28, p = 0.003) were significantly more likely to belong to group 1. However, parents who were willing to vaccinate their children with additional vaccinations due to migration were significantly less likely to answer all the questions correctly (OR = 0.21, p = 0.002)., Conclusions: Awareness of the epidemiological situation in Poland and Ukraine among parents is related to a greater awareness of the impact of migration and the use of recommended vaccinations and those against SARS-CoV-2. Additional vaccinations should be further promoted among both Poles and migrants.