Professor Karina Butler:

We revisit advice all of the time as evidence and the various factors that go into the generation of any advice come on board. Of course, safety is paramount. It is always a risk balance in terms of the very real threats of Covid and what Covid does, the benefits of the vaccine, what the alternative mitigating strategies are and what the alternate vaccine availability is. It very much depends on what else is in the mix. For example, if there were no Pfizer and no mRNA vaccines-----