In October the Human Medicines Regulations 2012 were updated to allow the MHRA to grant temporary authorisation of specific batches of the Pfizer/BioNTech Covid-19 vaccine without needing to wait for EMA approval. The approval is a temporary one which will last a year and allow the pharma company to complete specific obligations. Phase III trial data from the Pfizer BioNTech vaccine trial has not yet been published.
The MHRA are likely to have assessed data from lab and clinical trials in humans supplied to them . In addition their assessment would include the manufacturing , quality controls, product testing from sampling. The review has most likely been a “ Rolling Review “ process and the MHRA will have scientifically and methodically reviewed the safety, efficacy, and quality data on the vaccine and its mode of action and the protection it provides to the public before they gave their approval.