I see the Irish health authorities are invoking the "precautionary principle" in justification, here.
This has the appearance of being rational, but is anything but.
Rational would be a cost-benefit analysis of the likelihood of 10m doses of the Oxford vaccine being given to Brits without us noticing any obvious significant causal link to anything, combined with the literally tens of thousands of deaths prevented by these vaccines, versus this - whatever this is.
This kind of statement from medical professionals reveals the shortcomings of the (usually helpful) precautionary principle - it makes sense in the normal medical world (where caution helps, and where "do no harm" is the highest calling).
But we're in a pandemic, and medical professionals have to hold themselves accountable for "sins of omission" as much as "sins of commission" - i.e. you're doing direct harm by witholding vaccines that are within acceptable tolerances of safe.
The problem is that there's an asymmetry of blame - we crucify medical professionals for the interventions they make, but not for the interventions they don't make, but should - such as tolerating some risk in a vaccine programme, where speed is of the essence, in the name of more lives saved overall.