Okay, so if the binary thinking is wrong, why stop at three? Why stop at all? Does the science say we just blast our bodies with as much mRNA as we can get away with?

Elementary economic thinking answers this question.

Benefits asymptote, so you'll stop at the point where the marginal benefit of an additional shot is less than the marginal financial cost, marginal opportunity cost and marginal cost of side effects all combined.

That's definitely not the case before two and may not be the case before three based on data we've seen. It might be the case before four.

And this doesn't factor in declining immunity over time. It might make sense to keep taking shots every half a year forever, until COVID mutates into something less deadly perhaps.

This is basically what is done with the flu shot although it's a very different mechanism in the actual vaccine.

> until COVID mutates into something less deadly perhaps.

How do we know that that hasn't already happened? If we don't know, when will we know?

We will know when CFR/IFR goes down among unvaxxed people who haven't had COVID before.

Assuming you are asking earnestly, because of diminishing returns. Pfizer has been found to be 90 something percent effective at 2 months. They've noticed it seems to lose about 3% effectiveness per month, leaving you at 70-something percent after 8 months. That's with the data we have today, it could be much higher or lower as more data is collected.

To preemptively answer your question - yes, I could see needing to get a booster every 8 months for the foreseeable future.

"Assuming you are asking earnestly, because of diminishing returns."

The economics of this are showing increasing returns to the worldwide medical cartels, so this looks like it will continue indefinitely. With broad immunity to product safety laws, why not lay in another billion or two as profit? The C-level company staff will gleefully take home fat bonus checks.