Background In occurrence of the coronavirus disease 19 (COVID-19) pandemic, carrying out an efficient large-scale vaccination campaign is vital in order to control the virus. Especially in high prevalence areas of COVID – 19, it is crucial to implement an effective vaccination strategy. In Italy, programming an efficient COVID-19 mass vaccination campaign has been the main target of the Ministry of Health. Aims This paper gives a comprehensive overview of how the mass vaccination campaign is performed in Milan, one of the cities that has been mostly affected by the COVID-19 pandemic in Italy. We analyze the vaccination strategy implemented by Fondazione Ca’ Granda – Ospedale Maggiore Policlinico located in Milan. Furthermore, we compare the organization of this campaign in regards of those carried out across EU and UK. Materials and Methods The data derive from an analysis of the different vaccination plans implemented across EU and UK from the 27/12/2020 to the 15/06/2020. In addition, we discuss the data collected from the internal data server of IRCCS Fondazione Ca’ Granda – Ospedale Maggiore Policlinico from the 15/02/2021 to the 15/06/2021.The collected data are examined by means of descriptive statistics. Results From the analysis of the internal data server, we observe that the modular organization of Fiera Milano City guarantees up to 5000 vaccinations/day. Moreover, the precise flow organization of users and a series of strategies adopted to avoid identification errors or vaccine type administration errors are crucial to reach the aforementioned target. Conclusions The institution of mass vaccination centers thanks to the optimization of all the involved processes and the meticulous organization of these structures, allows to avoid crowds and guarantees the administration of elevated amounts of vaccines. All these elements assure a rapid vaccination coverage of the population in Lombardy, with a meaningful increase in daily administration doses.