I've been thinking the same things, that there is a small likelihood there's a nasty black swan hiding in there somewhere.

But in addition to the theory, we're approaching one year of empirical data on large-scale clinical trials, soon improving by the millions every day. So I'm less and less nervous for such a "holy shit, who could have imagined that" moment for each week that passes.

That the rare AZ/J&J side effects were promptly discovered is also a good sign that the monitoring system works.