What if the vaccine(s) had been announced before the election?

[Pericles]

If the proper process was followed, Trump would get a slight boost, maybe worth 0.6% of the margin. However most of the Covid focus would still be on his failed response, especially since he wasn't doing anything to save lives even for a few months given the imminent vaccine.

If Trump somehow rushed the process against scientific recommendations just so he could get a political boost, he might still get a political benefit but vaccine hesitancy would be much higher.

[Pericles]

If it was announced the day before the election, I'm not sure much would change.  If it was announced a month before the election (early enough not to look like a politically-driven decision and early enough to impact the bulk of early voting), it's almost surely enough to give Trump the EC win.

 


The PV would be Biden +2.5 or so, basically a repeat of 2016 with the earlier vaccine news playing the same role the Comey letter played then.

Part of why the Comey letter had such a big effect was that there were lots of undecideds still left on the table in 2016. In 2020, there were so few undecideds, plus many millions of people had already voted, so it's hard for any one event to even be worth 0.6% of margin for Trump.