FOI release
PFIZER BNT162b2 TRIAL PROTOCOL DEVIATIONS AND MHRA REGULATORY ASSESSMENT
Some or all of the information requested was not provided because we determined that the cost to do so would exceed the appropriate limit.
Case reference FOI2026/00929
Received 20 August 2026
Published 6 November 2026
Request
I refer to MHRA response FOI 23/211 dated 23 March 2023 concerning the imbalance in important protocol deviations in the pivotal Pfizer/BioNTech BNT162b2 clinical trial. That response stated that no formal investigation of the imbalance was undertaken but that the imbalance was noted during assessment but was not pursued because the proportions were considered low. 1.4% in the BNT162b2 group and 0.3% in the placebo group. Please provide the following recorded information only: 1 Copies of any contemporaneous MHRA assessment records, reviewer comments, assessment reports, notes, emails, meeting records or other documents recording or discussing the imbalance in important protocol deviations between the BNT162b2 and placebo groups. 2 Copies of any recorded analysis or consideration of whether that imbalance could have affected: a) the primary efficacy analysis b) the comparability of the randomised groups c) exclusion of participants from the evaluable efficacy population d) blinding or allocation integrity e) the reliability of the reported vaccine-efficacy estimate. 3 Copies of any recorded risk assessment, regulatory reasoning, criteria or other documentation supporting the decision that the imbalance did not require formal investigation or further pursuit. 4 Please provide any recorded sensitivity analysis, alternative analysis or other calculation undertaken by or supplied to MHRA examining whether exclusion or inclusion of participants affected by these protocol deviations altered the efficacy findings. 5 FOI23/211 stated that Pfizer subsequently provided an explanation that the imbalance largely reflected investigational-product handling requirements including ultra-low temperature storage, dilution and temperature excursions. Please provide: a) the date on which MHRA requested that information from Pfizer b) a copy of MHRA's request c) a copy of Pfizer's response d) any MHRA assessment, correspondence, notes or other recorded information considering whether Pfizer's explanation was independently verified or regarded as sufficient. 6 Please provide any recorded information showing whether MHRA examined the individual categories of protocol deviation before concluding that the overall imbalance was not significant enough to warrant investigation rather than relying solely on the overall percentages of 1.4% and 0.3%. For avoidance of doubt, I am not requesting the participant-level protocol-deviation lists already disclosed in connection with FOI 23/211 and I do not seek the creation of new analysis or explanations. I am seeking only recorded information already held concerning MHRA's regulatory consideration of this known imbalance and its decision not to investigate it formally. Where no recorded information falling within any particular part of this request is held, please state this explicitly.
Response
See attached
Documents
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