//...but I would be concerned that they had received appropriate training in treating adverse reactions, anaphylactic shock etc.//
Agreed. It's necessary for the job (though I imagine there are not too many retired doctors who had not already been trained in those topics).
This is an emergency. We're constantly told that lives are at risk so administering vaccinations will save lives. In May 1940 about 400,000 lives were at risk in northern France. Vice-Admiral Ramsay organised the evacuation of Allied troops from the beaches of Dunkirk. Large numbers of private craft of all shapes and sizes heeded the call to assist. Nobody asked whether the owner had his Masters' Certificate up to date; nobody checked the vessels to see they were seaworthy; nobody checked that insurance was in place to cover the boats. They just got on and did it and a third of a million troops were rescued in eight days.
If this happened today the civil servants in the Admiralty would be discussing, over tea and bikkies, whether the vessels that had volunteered their services were compliant with the latest environmental standards and whether their owners had been trained in Equality and Diversity. Meanwhile the troops on the beaches in Dunkirk would have been either taken prisoner or (more likely) simply cut down.
This is a similar emergency. I'm sorry but to suggest that the volunteers need training in "Recognising Radicalisation" or their insurance will be invalid is just about as daft as it gets.