Adverse event following immunization (AEFI) – any untoward medical occurrence that follows immunization, regardless of whether or not there is a causal relationship with the use of the vaccine. An adverse event following immunization may be any unfavorable and unintended change (including an abnormal laboratory finding), symptom, or disease.*

*Decision No. 87 of the Council of the Eurasian Economic Commission dated November 3, 2016 “On Approval of the Good Pharmacovigilance Practice Rules of the Eurasian Economic Union” (as amended by Decision No. 81 of the Council of the Eurasian Economic Commission dated May 19, 2022). Effective date — December 6, 2022.