Find the regulations here
https://www.gov.uk/government/public...ne-year-review
From section 3.1
Another respondent commented that the COVID-19 vaccines authorised under R174A had subsequently been linked to a very low number of adverse events, some of which had been serious, in particular the risks of myocarditis with both the Pfizer and Moderna COVID-19 vaccines and thrombosis with thrombocytopenia with the AstraZeneca COVD-19 vaccine. They noted that it was not clear whether these risks would have been identified had the vaccines been authorised under the usual arrangements of a CMA. They added that it was also not clear whether, if these risks had been identified, it would have influenced decisions by the MHRA in terms of licensing, given the public health emergency and subsequent authorisation of the vaccines under a CMA.
In light of these comments, it is important to note that each COVID-19 vaccine candidate was only authorised once it had met robust standards of effectiveness, safety and quality set by the medicines regulator, MHRA. The use of R174A did not alter this strict process and vaccines authorised via this route underwent the same rigorous quality checks as vaccines authorised under CMAs.
they didn't make it up on the back of a fag packet and the standards required still had to be met