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Review
. 2022 Jan;269(1):493-503.
doi: 10.1007/s00415-021-10747-8. Epub 2021 Aug 16.

Interpretation of vaccine associated neurological adverse events: a methodological and historical review

Marija Cauchi  1 , Harriet Ball  2 , Yoav Ben-Shlomo  2 , Neil Robertson  3
Affiliations
Review

Interpretation of vaccine associated neurological adverse events: a methodological and historical review

Marija Cauchi et al. J Neurol. 2022 Jan.

Abstract

As a result of significant recent scientific investment, the range of vaccines available for COVID-19 prevention continues to expand and uptake is increasing globally. Although initial trial safety data have been generally reassuring, a number of adverse events, including vaccine induced thrombosis and thrombocytopenia (VITT), have come to light which have the potential to undermine the success of the vaccination program. However, it can be difficult to interpret available data and put these into context and to communicate this effectively. In this review, we discuss contemporary methodologies employed to investigate possible associations between vaccination and adverse neurological outcomes and why determining causality can be challenging. We demonstrate these issues by discussing relevant historical exemplars and explore the relevance for the current pandemic and vaccination program. We also discuss challenges in understanding and communicating such risks to clinicians and the general population within the context of the 'infodemic' facilitated by the Internet and other media.

Keywords: COVID-19; Thrombosis with thrombocytopenia syndrome; Vaccination; Vaccine-induced thrombocytosis with thrombocytopenia.

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Conflict of interest statement

None of the authors have declared conflicts of interest.

Figures

Fig. 1
Fig. 1
Self-controlled case series: example timelines of three participants. Averaged across all people in the study, the rate of events A occurring in the at-risk time period is compared to the rate of events B in the control time period. Many factors which in other designs could be confounders are assumed to be constant within each person across their duration of participation. Only those who have experienced an event are included as cases
Fig. 2
Fig. 2
Hypothetical illustration of how potential vaccine-related complications could be investigated. NNTH = number needed to treat for harm
Fig. 3
Fig. 3
A visual depiction of balancing the benefits and harms when making population vaccination decisions. This shows how recommendations vary by age and prevailing infection rates. Reproduced with permission from A. Freeman and D. Spiegelhalter; for more information, see https://wintoncentre.maths.cam.ac.uk/ accessed 17/06/21
See this image and copyright information in PMC

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