A 6-week time period may not be sufficient to identify potential adverse events following COVID-19 vaccination (preprint)

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 posited that the reporting period for AEs related to the COVID-19 vaccines may be different. 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.