They have to massage those numbers to get any efficacy at all (see Cochrane Review). i believe the efficacy is actually NEGATIVE.

The thing you need to understand is that the whole mythology is so bad, that even making the cogent argument you are making, you accidentally affirm much of the mythology.

RNA virology is the worst. It is basically pure fraud.

Here are some conceits within your very reasonable and logical argument that you cannot just pass over.

1) there is a “flu virus” and it has a specific sequence or structure (H1N1 for example) which makes it cause flu—and that this sequence moves around the world.

2) Causality of “the flu” (whatever that is) is fully established.

3) Antibodies are correlate of immunity.

4) specific antibodies are for specific diseases—we can see what those antibodies are, and therefore know the disease.

there is more.

Much more.