[evanmoran]

The better argument for first doses first is the expectation that vaccine supply and delivery will rise significantly in the near term. This would allow a country to start everyone’s vaccination timeframe sooner with a strong expectation that supply would bring second doses closer to the normal timeframe over time.

It sounds like Canada’s approach is aware of this as it is “extending the second dose of COVID-19 vaccine up to four months after the first.”

This maximum of four months is a solid approach because either (1) the science is solid and net more protection is offered to the country, or (2) the science is just ok, but the supply and delivery improvements will actually allow for on time doses at a faster pace then previously possible