Thank you for that, Steve.
Mr. Chair and honourable member, the portfolio approach that we've taken has proven robust. A number of the vaccines that we were hoping would be part of our immunization campaign have had challenges—sometimes in production and sometimes in their approval—and so the net result is that we've ended up with a couple of vaccines that are playing a very foundational role.
As you would know, both Pfizer and Moderna have been a major part of what we've done, as well as AstraZeneca to a lower level. Having that diversity of options, in fact, has been very beneficial for the country and therefore I think the portfolio's been quite advantageous.
With respect to the difference among them or the quality—