Due to the devastating COVID-19 pandemic, a preventive tool in the form of vaccination was introduced. Thoracic cancer patients had one of the highest rates of morbidity and mortality due to COVID-19 disease, but the lack of data about the safety and effectiveness of vaccines in this population triggered studies like ours to explore these parameters in a cancer population. Out of 98 patients with thoracic malignancies vaccinated per protocol, 60–75% experienced some adverse events (AE) after their first or second vaccination, most of them were mild and did not interfere with their daily activities. Out of 17 severe AEs reported, all but one were resolved shortly after vaccination. No significant differences were noted considering AE occurrence between different cancer therapies received after the first or second vaccination dose, p = 0.767 and p = 0.441, respectively. There were 37 breakthrough infections either after the first (1), second (13) or third (23) vaccine dose. One patient died as a direct consequence of COVID-19 infection and respiratory failure, and another after disease progression with simultaneous severe infection. Eight patients had moderate disease courses, received antiviral therapies and survived without consequences. Vaccination did not affect the time to disease progression or death from underlying cancer.