Table 3

Suggested criteria for labelling causality in neurological AEFI

Causality labelAssessment criteriaConsiderations for neurological AEFI
ProbableTypical time frame.
No indication of an alternative aetiology.
No risk factors.
For immune-associated AEFI, <6 weeks from vaccination.
No risk factors or alternative aetiology identified by the means of clinical, laboratory, radiological and electrophysiological assessment, as indicated.
PossiblePlausible time frame, but outside of typical.
There may be an indication of an alternative aetiology and/or risk factors, but these are unlikely to explain the event.
For immune-associated AEFI, 6–12 weeks from vaccination.
Presence of risk factors, such as a previous episode of Bell’s palsy in a patient with postvaccination Bell’s palsy.
UnlikelyTimeline not in keeping with prior established temporal associations
Alternative aetiology and/or risk factors fully explain the event.
For immune-associated AEFI, <24 hours or more >12 weeks from vaccination.
Clear alternative aetiology, such as Campylobacter diarrhoea preceding GBS.
  • AEFI, adverse events following immunisation.