Disproportionality analysis of adverse neurological and psychiatric reactions with the ChAdOx1 (Oxford-AstraZeneca) and BNT162b2 (Pfizer-BioNTech) COVID-19 vaccines in the United Kingdom

Background Information on neurological and psychiatric adverse events following immunization (AEFIs) with COVID-19 vaccines is limited. Research design & methods We examined and compared neurological and psychiatric AEFIS reports related to BNT162b2 (Pfizer-BioNTech) and ChAdOx1 (Oxford-AstraZeneca) COVID-19 vaccines and recorded in the United Kingdom Medicines and Healthcare products Regulatory Agency between 9 December 2020 and 30 June 2021. Results As of 30 June 2021, 46.1 million doses of ChAdOx1 and 30.3 million doses of BNT162b2 had been administered. The most frequently reported AEFI was headache with 1,686 and 575 cases per million doses of ChAdOx1 and BNT162b2, respectively. AEFIs more frequently reported after CHAdOx1 compared with BNT162b2 vaccination were Guillain-Barre syndrome (OR, 95% CI = 2.53, 1.82-3.51), freezing (6.66, 3.12-14.22), cluster headache (1.53, 1.28-1.84), migraine (1.23,1.17-1.30), postural dizziness (1.24,1.13-1.37), tremor (2.86, 2.68-3.05), headache (1.40, 1.38-1.43), paresthesia (1.11, 1.06-1.16), delirium (1.85, 1.45-2.36), hallucination (2.20, 1.82-2.66), poor quality sleep (1.53, 1.26-1.85), and nervousness (1.54, 1.26-1.89) Reactions less frequently reported with ChAdOx1 than with BNT162b2 were Bell's palsy (0.47, 0.41-0.55), anosmia (0.58, 0.47-0.71), facial paralysis (0.35, 0.29-0.41), dysgeusia (0.68, 0.62-0.73), presyncope (0.48, 0.42-0.55), syncope (0.63, 0.58-0.67), and anxiety (0.75 (0.67-0.85). Conclusion Neurological and psychiatric AEFIs were relatively infrequent, but each vaccine was associated with a distinctive toxic profile. Plain Language Summary We examined reports on adverse neurological and psychiatric effects following immunization with BNT162b2 (Pfizer-BioNTech) and ChAdOx1 (Oxford-AstraZeneca) for COVID-19 to the United Kingdom Medicines and Healthcare products Regulatory Agency between 9 December 2020 and 30 June 2021. Adverse effects following immunization (AEFIs) were relatively infrequent. Compared to BNT162b2, Guillain-Barre syndrome, freezing phenomenon, cluster headache, migraine, postural dizziness, tremor, headache, paresthesia, delirium, hallucination, poor quality sleep, and nervousness were more frequently reported for ChAdOx1. Reactions less frequently reported for ChAdOx1 than for BNT162b2 were Bell's palsy, anosmia, facial paralysis, dysgeusia, presyncope, syncope, and anxiety.