Update on Selected Adverse Events of Concern Following Immunization With Acellular Pertussis Vaccines, a Narrative...

To provide an update paper on evidence of adverse events of concern following immunization (AEFI) with pertussis vaccines, focusing primarily on acellular (aP) vaccines.

Evidence was synthesised from epidemiological studies, systematic reviews over recent decades, expert interpretations in reviews from relevant research teams and well-conducted observational reports across different time periods. A more comprehensive review of the literature was conducted for certain specific AEFIs, including sterile abscesses, macrophagic myofasciitis, reactions to aluminium adjuvants, Guillain-Barré syndrome, acute disseminated encephalomyelitis (ADEM) and anaphylaxis.

Acellular (aP) vaccines are generally associated with mild reactions such as local pain, redness, and transient fever. Moderate reactions, including prolonged crying, hypotonic-hyporesponsive episodes, extensive limb swelling, and aluminium-induced granuloma, occur infrequently and are self-limiting. Severe outcomes such as seizures or encephalopathy have been extensively investigated, with large studies showing no consistent increase above background incidence.

Licensed acellular pertussis vaccine combinations demonstrate acceptable safety profiles, with serious adverse events being rare. Continuous pharmacovigilance and balanced, evidence-based communication remain essential to sustain trust in pertussis immunisation programmes.