That's a good point, but would Saskatchewan (~68% of population fully vaccinated) and Montana (~50% apparently) have enough of a difference in their vaccination rates to do a similar comparison as was done for Israel and Palestine?

Though now that I mention that, perhaps he could also look at Israel (a little over 60% of total population fully vaccinated) v Jordan (35%)?

Looking back at subnational units though, perhaps Manitoba (72%) v North Dakota (46%)?