The vaccines against COVID-19 are the best treatment for limiting the spread of the epidemic, and from an individual point of view, for avoiding getting sick. A cross-sectional retrospective survey was conducted from 15 May to 15 July 2021 among healthcare workers, including doctors, nurses, midwives, and students at the Medical University of Lodz (nursing, midwifery and medical students) in Poland. Data were obtained from 1080 participants. The aim of the study was to evaluate vaccination coverage against COVID-19 among healthcare workers (HCWs) in Poland, and to analyze their attitude towards the available vaccines, stress before taking, and side effects after administrating them, and motivation towards continuing vaccination in the future (if necessary). The survey also estimated the frequency and quality of adverse post-vaccination reactions after two doses of BioNTech/Pfizer and two doses of AstraZeneca vaccines. The present study revealed that the vaccination ratio after 6 months from the start of vaccination against COVID-19 in Poland among HCWs was very high at 91.2%. However, doctors and medical students were more likely to be vaccinated than nurses and midwives, and nursing and midwifery students (94.8%, 98.3% vs. 78.9% and 86.3%, respectively). The main reasons that HCWs reported receiving a vaccination were to protect the health of themselves and their families, while the main reasons for avoiding a vaccination were fear of side effects, doubts about effectiveness, and an expedited clinical trial process of vaccines. Furthermore, more than two-thirds of those vaccinated reported side effects after receiving at least one dose of the vaccine. Most of the side effects were short-term symptoms with only slight and moderate intensification. The univariate and multivariate logistic regressions showed that the type of vaccine used had a significant impact on the occurrence of adverse post-vaccination effects and the severity and duration of vaccination symptoms. In addition, chronic disease and fear of vaccination also had some influence. Despite this, most participants (more often older than younger participants; p < 0.001) were in favor of compulsory vaccination against COVID-19 for HCWs.