Background. Messenger RNA (mRNA) vaccines have been widely used as the main sanitary measure destined to fight the COVID-19 pandemic. Rapidly purported as being "safe and effective", this new generation of vaccines is radically different from those developed traditionally and for which potentially associated adverse events (AEs) are considered through a standard 6-week post-vaccination period. Hypothesis. Here, we posit that the reporting period for AEs related to the COVID-19 vaccines may need

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... to be longer. Method. In this retrospective, observational study, we aimed to assess the chronology of new/worsening ailments occurring after the administration of COVID-19 vaccines based on the changes to the participants' pharmacological records. Patients vaccinated against COVID-19 and experiencing health-related events during the study period (between September 30, 2021 and July 15, 2022) were included and the changes to their pharmacological records were analyzed. Results. One hundred and twelve (112) adult patients (63 men, 49 women; 67.54 ± 14.55 years-old; mean ± standard deviation) have reported changes to their pharmacological record following health-related events, which occurred 11.57 weeks (median; range 0.04-47.14) following their last COVID-19 injection of 3 doses (median; range 1-4). The most frequent medical ailments that appeared or worsened were cardiovascular diseases (CVD; N=61), cancer (N=31), respiratory diseases (RD; N=22) and zona (N=10), half of which occurred after the second dose. Nineteen (19) patients (10 men, 9 women; 78.2 ± 11.4 years-old) died on average 17.14 weeks (SD 13.71) after their last injection. Conclusion. Most (76.1%) of the health-related events experienced by patients vaccinated against COVID-19 occurred beyond the 6-week period prescribed by the health authorities. Our findings call for further investigations and an extension of the post-vaccination AE reporting period.