After defining what vaccinovigilance is and its purposes, Dr. Finizia of GSK continued the talk at the 58th AFI Symposium, focusing on vaccine reactions, called AEFI.
AEFI (Adverse Event Following Immunization) is any unwanted medical event that occurs after immunization and which does not necessarily have a causal link with the use of the vaccine. It is defined and classified by generating cause:
- vaccine-dependent reaction: caused by the vaccine due to one or more of its intrinsic properties (e.g. reaction to one of its components)
- reaction related to a quality defect of the vaccine: caused by the vaccine and due to a manufacturing or device defect provided by the manufacturer for administration (e.g. contamination)
- reaction related to an administration error: caused by inappropriate use of the vaccine both in terms of prescription and administration and therefore preventable by its nature (e.g. incorrect storage, contraindications not observed, errors in reconstitution)
- anxiety-related reaction: a reaction due to anxiety for vaccination (e.g. fainting, lipotemia)
- coincident reaction: arising from a cause other than a vaccine, an error in administration or anxiety, but which occurs in a time close to vaccination (e.g. onset of a related disease)
- vaccination failures: the appearance of vaccine-preventable disease, in vaccinated subjects, taking into account incubation time vs. time needed to acquire immunization.
All vaccine reports must be evaluated on the basis of:
- information on the vaccine: personal / family history, vaccination history, concomitant conditions, details of the vaccination
- information on the AEFI: serious/not-serious, events of special interest, the possibility of clusters
- information on the vaccine: lot, expiry date, composition, biological characteristics, the possibility of production or contamination defects
- information on vaccination: errors in administration, storage, non-compliance with contraindications
- completeness/coherence of the case: possibility of temporal coincidence or events related to anxiety
- degree of reliability: presence or absence of medical confirmation, confounding factors, personal perception of the reporter
- possibility of a causal link: through the use of algorithms (e.g. WHO), clinical evaluations (pharmacological plausibility, alternative etiology, comparison with other DBs, disproportionality, etc.).
Unfortunately, as pointed out by Mrs. Finizia, for vaccines there is a limited acceptance of any potential risk, as the purpose of the vaccine is to reduce the diseases in the population. Consequently, the immediate perception of benefits at an individual level results in a poor acceptance of the risk of adverse reactions, even if only potential ones.