I have served on or chaired two dozen data safety monitoring boards for randomized trials of novel experimental drugs or devices. I can tell you firsthand for COVID-19 vaccines, a 30-day regulatory window after injection is fair game for attribution of adverse events to the product when the special complications of interest are known to be caused by the mRNA induced Wuhan Spike protein.
Jabagi et al., NEJM, reported from the French National Health Data System linked to the national COVID-19 vaccination database disclosing cardiovascular events after mRNA BA4/BA5 bivalent boosters. All persons who were 50 years of age or older and who had received a booster dose between October 6 and November 9, 2022, were included in the study. The composite of ischemic/hemorrhagic stroke, myocardial infarction, or pulmonary occurred in 335 unfortunate individuals.link