Immunization anxiety-related reactions or Immunization Stress Related Response

Classification of AEFIs

The term “immunization anxiety-related reaction” is used to describe a range of symptoms and signs that may arise around immunization that are related to “anxiety” and not to the vaccine product, a defect in the quality of the vaccine or an error of the immunization programme. These reactions are described as AEFIs arising from anxiety about immunization and include vasovagal-mediated reactions, hyperventilation-mediated reactions and stress-related psychiatric reactions or disorder.106

Acute stress response Vasovagal reaction Dissociative neurological symptom reactions
An acute stress response is an internal physiological response to a threat in all mammals and is often referred to as a “fight or flight” response. It may manifest with variable severity of symptoms and may range from mild feelings of worry and “butterflies” in the stomach to sympathetic stimulation: increased heart rate, palpitations, difficulty in breathing or rapid breathing (hyperventilation). A vasovagal reaction manifests as symptoms of mild dizziness or a brief loss of consciousness (syncope) because of insufficient blood flow to the brain after loss of blood pressure due to a decreased heart rate or vasodilatation of blood vessels. It may be associated with prodromal symptoms such as nausea, sweating or pallor. Some individuals who experience syncope may also have a syncopal seizure. Dissociative neurological symptoms and signs can include weakness or paralysis, abnormal movements or limb posturing, gait irregularities, speech difficulties, and non-epileptic seizures with no apparent physiological basis. The symptoms and signs may take hours to days to develop after immunization. DNSRs appear to be more common in females; they are not usually diagnosed in infants. In children, DNSRs usually manifest as single symptoms.
Classification of stress responses and reactions
Classification of stress responses and reactions