[katieHaylor (OP)]

Barrie says:

Surely, there needs to be a dose response trial in the vaccine trials.  If the (accidental) low first dose is effective then it could be that a second low dose could also be effective.  This would reduce the overall amount of vaccine required considerably. Should there now be a test of even lower doses?

[alancalverd]

There's still some debate about the "accidental" half dose. It seems that some shots were manufactured at half  dose in error, but intentionally used as part of a dose-efficacy investigation that turned up with an unexpected answer.

IMHO this is not the time for much further investigation unless clinical practice turns up a lot of adverse reactions. At this stage the overriding priority is to minimise the effect of government incompetence and public stupidity by whatever means we have available.