CV and mad panic behaviour

[Baggers]

I recall that when we all (warning: another tired Navy story!) lined up for a barrage of inoculations at recruit school (HMAS Cerberus) there was an expectation that a small number of blokes would react badly, some even hospitalised, and would subsequently not be able to join. We received yellow fever, TB, smallpox and another I forget all in one go. Apparently a few young blokes per year would end up in a critical condition or worse.

The point of this missive is that there was one inoculation (vaccination) where every one had a test for tolerance... a tiny injection under the skin of the forearm (underside) to test reaction (think it was smallpox, maybe TB). If a small watery blister came up in a few days you would good to go for the major injection. If not, you were discharged as the major injection would be very problematic. I wonder if a tiny, test dose could be used for Covid variants and other future nasty viruses to ascertain some level of suitability?