In the 21st century the value of vaccination in protecting health from infectious diseases is recognized by the entire scientific community. However, there are still people, and especially young children, who remain unvaccinated or experience the vaccination process traumatically, partially due to the fear and anxiety of the impending needle prick. To address this problem, in with work we develop a playful extended reality technology application named VaccineHero. VaccineHero aims to assist childhood vaccination, limiting or eliminating the negative emotions that children often feel before and after the vaccination process. During the vaccination process, which includes the child, a doctor, and optionally a nurse, the child becomes immersed in the virtual environment, thus avoiding most of the discomfort they would experience in the conventional vaccination procedure.