What other prophylactic treatments do you take in your life before or after COVID? Because in my lifetime I can think of only a small number of classes of general prophylactic treatments I've ever seen a small number of groups of people take.
- Silicon valley rationalist types taking stacks of vitamins despite having no evidence on bioavailability because they are generally without side effects and who knows, you might live forever. I think the consensus on this now is that more or less this is not a useful practice, though I am unaware of any evidence for it being unsafe.
- Prophylactic hormone replacement therapy in middle aged women, which was eventually generally recognized as unsafe because of unexpected cancer risks not initially understood.
- Prophylactic breast self-examination, mammograms, and prostate exams based solely on age, the former of which have been significantly dialed back over the last decade because the risk of false positives or catching slow-growing low risk cancers causes a net negative from the treatment. I don't know what the state of prostate exam research is.
- Prophylactic aspirin for heart stuff: we seem to go back and forth on this, but the last I read was that actually there's mounting concern about chronic low-dose aspiring. At the very least, it's not obvious this is doing anything.
- Statin treatment in response to mild elevated blood pressure with no symptom of disease; not exactly prophylactic, but close in the sense that it's about advance management of expected disease. And last I read, researchers were increasingly recommending dialing back statin treatment for minorly elevated blood pressure because of, again, unforseen side effects.
So I just mention this to say that what I take from your post is "the precautionary principle suggests giving more weight to prophylaxis with no known side effects" and what I take from major medical stories in my lifetime is "no known side effects almost always turns out to involve side effects in the end, and that has to be part of the precautionary principle as well".
And I should note all of the above prophylaxis is based on clearly defined treatment regimens and physician supervision, not the kind of wild west ordering various formulations of ivermectin at unknown doses with or without medical supervision on an ad hoc basis.