The DfT has recently produced a Traffic Advice Leaflet, showing examples of Vaccination centre signs.
It points out that temporary signs can be done under Schedule 13 part 9, and gives a number of examples.

Of course KeySIGN is very capable of producing these designs and other variations quickly and simply, however as I am keen to see these signs appearing on our roads I thought I'd provide you with a DWG you can use as a starting point in your designs.
There are two dwgs attached. For KeySIGN versions 19.3 to 19.6 please use CovidVaccination193.dwg. For KeySIGN versions 20.0, 20.1 (and 21.0 in the future) please use CovidVaccination200.dwg.
Just as a design pointer. I have had to remove the 'autoformat' tick off the COVID-19 text to remove the usual design gaps beside the hyphen. Also I have lessened the border spacing from roundabout stubs to make them 2.5sw.
Hope you find these useful, and got a little bit excited like me to see the words on these designs
Alan