What evidence does he have of actual transmission? I want to see actual studies with humans with breakthrough infections giving infections to other humans. I'd like to see one contact tracing case where a breakthrough infection was the index patient that spread it to multiple people at a given venue.

I've already posted studies which contradicts the idea that breakthrough infections are equivalent to unvaccinated infections in terms of actual live viral load, which should show up as reduced transmissibility. And the reduction in severity of symptoms with vaccination is highly unlikely to come without a corresponding reduction in transmissibility. What is his scientific data showing that viral loads, symptoms and transmissibility have somehow become completely decoupled?

And we seem to have forgotten that most of the spread of this disease is caused by individual superspreaders. Only 20% of the infections are responsible for 80% of the forward transmission. If vaccines reduce severe transmission the same way they reduce severe disease then they could very well have a disproportional impact on r0.

> It's impossible to reach 100% coverage

The fact that we can't hit 100% coverage doesn't imply that vaccines in the population that we can vaccinate aren't highly effective at reducing transmission.

Also if you're just making an argument by authority, then go watch all the recent TWiV episodes. I don't necessarily agree with Herr Professor Doktor Racaniello about everything (delta really is a lot more transmissible/virulent), but the whole crew there would tend to agree with me, and wants to see the real transmissibility studies with real humans infecting real humans.