The event itself was not unusual per se, the rollout of the vaccinations (of which two injections, spaced apart, are required), but the way in which it was broadcast to the world marked a unique moment for the royals - and it'll be a moment both they themselves and their fans will likely not forget.
In a statement released to media on the same day, a Buckingham Palace spokesperson confirmed: "The Queen and The Duke of Edinburgh have today received Covid-19 vaccinations."