He and Covid are just making estimated guesses. Casey's is based on using the past 7 day averages, and so that will not end up being the case of what will end up happening.
Neither will actually know what vaccines will be delivered to each jurisdiction and and at what rate.
Plus even the Feds probably do not know either exactly when the Pfizer and Moderna will arrive for them to distribute.
And then overlaying all that is what rate people actually choose to try and get vaccinated.
ie Just with the over 60's who are not vaccinated you will have some who:
- will never get vaccinated,
- some who are stubbornly waiting for Pfizer even though they may die from catching covid in the interim
- some who will get vaccinated eventually