>>First, Fauci has already gone on record as saying the 2nd vaccination provides much stronger protection against mutations.
There's an Israeli study showing that the Pfizer vaccine gives some protection after 1 dose but most of its benefit after the 2nd dose. This includes the UK variant, fwiw. The second dose was given at 3 weeks in this study compared to longer delays elsewhere.
Fauci was worried that delay may select for stronger strains that need the second dose for optimum effectiveness.
Not all the vaccines need 2 doses, fwiw. E.g. the Johnson and Johnson effort needs only one dose, or so they say today.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
