In a similar way: mask mandates and usage have been
extremely commonplace around the world for months now. If there was
any empirical evidence that they did anything to prevent deaths, "cases," or any other measure of spread, it would be shouted constantly from the headlines of every media outlet. The fact that, as of November 2020, the best they can manage for "proof" are hypotheses about droplets and viral loads.
In fact, the data we do have suggests very strongly that
general mask usage doesn't do crap. It's a religious talisman in more ways than one: a way for panicked, scared people to believe they have control in an uncontrollable and uncertain situation, and a visible marker of faith and piety, that the wearer is, if not a Good Person and believer, at least someone who has submitted to the faith.