Rapid vaccination may be of benefit in long-term care facilities (LTCF) that are affected by an ongoing COVID-19 outbreak. However, there are concerns regarding the safety and effectiveness of such an approach, particularly regarding the vaccination of pre-symptomatic patients. Here, we report the effectiveness of vaccination in a German LTCF hit by an outbreak that was detected 5 days after the first vaccine doses were administered. In detail, 66.7% of the unvaccinated patients experienced an unfavorable course; this proportion was much lower (33.3%) among the vaccinated patients. Even though this study is limited by a small number of patients, the observation and the comparison with related published data shows that vaccination (i) is safe and (ii) may still be of benefit when given shortly before an infection or even in pre-symptomatic LTCF-patients.