Infection rate is not that important as the vast majority of infections are in the unvaccinated. What's more important is that the countries concerned have good monitoring for variants. That's why the UK is there = they have the genome sequencing resources and are watching like a hawk (they were among the first to identify AY.4.2).
David, yesterday's announcement caught everyone by surprise. They have procedures to change, systems to update and then they have to communicate all this to embassies. I would suggest holding fire for a week.