Phase 3 trials are typically not big enough to find this level of risk. It took millions of jabs to find a slightly elevated risk, and this I think has to be c

Phase 3 trials are typically not big enough to find this level of risk. It took millions of jabs to find a slightly elevated risk, and this I think has to be compared to some other commonly applied vaccine, not placebo. If the risk is "very rare", like less than 1 in 10000, then it warrants a label and maybe precautionary dose of aspirin.