Now, obviously, this sort of thing hasn’t been tested, so there’s no data to support that sort of strategy. But is there even any sort of reason to think that it would be effective? I suppose that two vaccines that are similar enough in functionality might be expected to work well in tandem, but what about, say, an mRNA vs vector virus vaccine or inactivated virus vaccine? Is the idea that you just need to get enough of the antigen into the system?
It seems like that can’t be quite all there’s to it—I mean, I know that the currently administered vaccines have a difference in time interval between the two shots, presumably affecting efficacy—so do you just average the delay and hope for the best?
So, is this likely to be an effective and safe treatment? Or is this just the grasping at straws it seems?
As @FigNorton’s cite indicates, there was never a recommendation that a different vaccine may be substituted. In fact, the clear guidance is that different vaccines shouldn’t be mixed.
But, if for whatever (hopefully very rare) reason the first dose can’t be identified when it’s time to get the second dose, it’s better to take a guess and get something than get nothing. At worst, it’s a 50/50 chance to get the right second dose. And there is some evidence that even a single dose of the Pfizer vaccine gives some protection. So either way, something is better than nothing.