In the case of hydrochloroquine, Trump was saying "this is bigly magical" and every expert around was urging caution. With a (proper, tested) vaccine expert opinion would be a lot more friendly. People do consider the source; most people would not take medical advice from a hotel magnate (even people generally friendly to Trump were mostly cautious of the chloroquine and disinfectant imbibing stuff), against advice of actual doctors.
That said, mass availability of anything by November is probably optimistic.
That said, mass availability of anything by November is probably optimistic.