The aim of this present research was to test whether the discourse of groups opposed to the acceptance of COVID-19 preventive measures could be framed within conspiracy theories and to analyse their arguments. This study was conducted using quantitative methodology by applying the technique of content analysis to the messages sent within the denialist collective Docentes por la Verdad Telegram mesanging application group. The data collection timeframe was from December 2020 (when vaccination against COVID-19 started) to May 2021 (when the vaccination schedule for the majority of teachers ended). Systematic sampling with the function K = N/n was used to select sufficient days within this aforementioned date range to comply with a 95% confidence level and error of 5%, resulting in a sample of 124 from a total of 182 days. The pre-coding of the analysis was based on Brotherton's (2013) characterisation of conspiracy theories and the denialist arguments detected by the Comision Central de Deontologia de la Organizacion Medica Colegial (Central Commission of Deontology of the Spanish Medical Association; 2020). The results showed that these collectives can be considered conspiracy groups and reaffirmed the arguments of other research groups while also adding some new lines of enquiry.