[ttul]

This is easy to say if one is living in the country with all the vaccine supply. Canada bought more doses per capita than any other country, yet US prohibitions on vaccine export meant Canada could not get enough supply in the first few months of the vaccine rollout. A calculated risk was taken to give first doses while waiting for supply to come online, which did eventually happen.

This was not some random experiment on the population. While the gold standard of a phase three trial was not available to support the longer interval, there was plenty of data about the performance of prior vaccines, and interim data about immunogenicity with a longer interval for the COVID-19 vaccines.