The chancellor will give an update on Thursday about "protecting jobs" as the furlough scheme winds down.
There have been 6,178 cases in the UK in the last 24 hours, up 1,252 cases since Tuesday.
The Treasury says "now is not the right time to outline long-term plans".
His "non-partisan" plea has caused controversy, since royals are expected to stay politically neutral.
Its staff will soon offer customers disposable face masks to be paid for at the end of their trip.