Define Adverse Events Following Immunisation. Describe its classification, management and prevention.

Definition

• An Adverse Event Following Immunisation (AEFI) is any untoward medical occurrence which follows immunisation and does not necessarily have a causal relationship with the vaccine.
• Robust AEFI surveillance maintains public trust in immunisation.

WHO Classification (BY Cause)

Common Aefis

• Minor (common) — fever, local pain/redness/swelling, irritability (usually self-limiting).
• Severe/serious — anaphylaxis, seizures, persistent screaming, injection abscess, BCG lymphadenitis/disseminated BCG, VAPP.

Management

• Minor — reassurance, antipyretics, local care.
• Anaphylaxis — immediate intramuscular adrenaline, airway/oxygen, IV fluids (every session must have an anaphylaxis kit).
• Reporting and investigation — notify serious/clustered AEFIs through the surveillance system; investigate to determine causality and correct programmatic errors.

Causality Assessment

Serious AEFIs are investigated and classified (consistent causal association, indeterminate, coincidental, or unclassifiable) using a structured WHO framework, so that genuine vaccine reactions are separated from coincidental events and programmatic errors.

Surveillance Structure

• Reporting from the periphery upward, with district/state AEFI committees reviewing serious events.
• The goal is early detection, correct response, and maintenance of public confidence.

Specific Examples

• Injection abscess/cluster → suspect an immunisation (sterility) error.
• BCG lymphadenitis/disseminated BCG → consider underlying immunodeficiency; VAPP → OPV-related.

Minor VS Serious Aefi (summary)

Maintaining Public Confidence

Transparent reporting, prompt management, and clear communication about coincidental vs genuine reactions are essential — misattributed AEFIs can undermine an entire immunisation programme.

Key Principles of Aefi Response

Treat the patient (e.g. Adrenaline for anaphylaxis) → Report through the surveillance system → Investigate serious/clustered events → Assess causality → Correct any programmatic error & communicate

Examples BY WHO Category (quick Table)

WHY Aefi Surveillance Matters

Effective AEFI surveillance protects children (by detecting genuine safety signals and programmatic errors) and protects the programme (by countering misinformation), thereby sustaining the public confidence on which high coverage depends.

Prevention of Programmatic Errors

• Correct technique — right vaccine, dose, site, route, diluent; one sterile syringe per child (AD syringes).
• Proper reconstitution and use within the recommended time; cold-chain maintenance; trained staff.