Objective To explore people's decision‐making regarding whether or not to get vaccinated against COVID‐19. Methods A purposive sample of people over the age of 18 who had not yet been vaccinated against COVID‐19 was studied. Data were gathered using semi‐structured interviews in focus groups and personal in‐depth interviews. All interviews were conducted on the Zoom ® platform and were recorded for subsequent verbatim transcription. Using a grounded theory approach, both open and axial coding of the narrative data were performed. Results Information saturation was reached after eight focus group meetings and 14 in‐depth interviews ( n = 55). Six principal themes emerged, with the fear of possible adverse side‐effects and the worries generated by the speed of the development and commercialization of the vaccine amongst the main expressed anxieties. Social pressure to get vaccinated was a recurrent subject, as was the desire for clear and understandable information from reliable sources. Conclusions The willingness to get vaccinated against COVID‐19 is determined by a complex series of interconnected factors that define an explanatory model, which has evolved concurrently with the development of the vaccines and the progress of the vaccination campaigns. This model will be useful for deciding social scenarios aimed at tackling this or future pandemics and for designing formulas that will increase the initial acceptance of these vaccines.