This is a matter of the evolution of the science. It's really as simple as that. We're learning more about the effectiveness of vaccines. We're learning more about the efficacy of one dose or two doses. This is all quite expected in the context of watching the population in its response to vaccines and watching vaccines as they interact with our population. To be quite clear, it is us as a globe learning through the science how to use vaccines most effectively. That's what this conversation is about.
When Moderna and Pfizer were authorized for use in Canada, they were authorized according to the clinical trial data that the companies brought to the regulator. Once the vaccine is in use in a population, as with all vaccines, you then look at effectiveness in the real world, and you start to understand whether or not the way the vaccine is being delivered in the population can be revised, and whether or not those adaptations that you might make are having significant public health benefits. If they are, then you can modify your use. If you see that things are moving in the wrong direction, again, you modify your use. It is squarely the evolution of science.