Perhaps I can start and then turn to my officials.
So far, that is why we're watching so closely the variants of concern. Obviously, there's research worldwide to understand their impact on vaccination. There's some limited research that some of the variants may have an impact on vaccine effectiveness, but none that completely negate vaccine effectiveness. That is the research that's under way right now worldwide. In fact, manufacturers have been very clear that in some cases they can adjust the formula, so to speak, to address the rise of new variants and to ensure that their vaccine remains effective against new variants of the disease.
I'll turn to Dr. Lucas who may know more from a regulatory perspective.