Adverse Events Following Immunization (AEFI)

BASIC CONCEPTS

Definition of AEFI

An adverse event following immunization (AEFI) is any untoward medical occurrence which follows immunization and which does not necessarily have a causal relationship with the usage of the vaccine

The adverse event may be any unfavorable or unintended sign (e.g. Abscess following vaccination), abnormal laboratory finding (e.g. Thrombocytopenia following measles vaccination) symptom or disease (e.g. Disseminated BCG infection following BCG vaccination).

Types of AEFI for Reporting

For purpose of reporting, AEFIs can be minor, severe and serious.

Vaccine Reactions

1. MINOR REACTIONS

• Usually occur within a few hours of injection
• Resolve after short period of time and pose little danger.
• Local (includes pain, swelling or redness at the site of injection).
• Systemic (includes fever, malaise, muscle pain, headache or loss of appetite). 

• Caused when recipient’s immune system reacts to antigens contained in the vaccine.

• Immune response to the vaccine's antigen can cause local and systemic reactions:

  -E.g. pain, fever, swelling, loss of appetite

• Other vaccine components can also trigger reactions

  -E.g. adjuvants, stabilizers, preservatives

• A "good" vaccine keeps even minor reactions to a minimum, while producing best possible immune response.

Minor vaccine reactions are part of the body’s immune system and occur more often than severe, but usually heal.

Minor Reactions

Minor Vaccine Reactions: Examples

Minor vaccine reactions, treatments and rates associated with childhood vaccines

2. SEVERE REACTIONS

  * Usually do not result in long-term problems.

  * Are rarely life threatening.

  * Include seizures and allergic reactions caused by the body's reaction to a particular component in a vaccine.

Severe Vaccine Reactions: Examples

Severe vaccine reactions, treatments and rates associated with childhood vaccines

3. SERIOUS REACTIONS

  * Death

  * Inpatient hospitalization

  * Persistent or significant disability

  * AEFI cluster

  * Congenital anomaly

  * Parental / community / media concern

Serious and severe reactions

  * Can be disabling and, rarely, life threatening

  * Most do not lead to long-term problems

  * Must be reported

Serious reactions

  * Results in death.

  * Requires inpatient hospitalization.

  * Results in persistent or significant disability.

  * Congenital anomaly/birth defect

  * Cluster

  * Community/media concern

WHO cause specific definition of AEFIs

Examples

AEFI Cluster

Definition of Clusters of events

Clusters of events is two or more cases of the same adverse event related in time, place or vaccine administered.

Clusters can be usually associated within:

• a particular provider
  or health facility

• a vial/vials of vaccine
  that has/have been

  Inappropriately prepared 

  Contaminated

  Inappropriately stored

  (e.g. freezing vaccine during transport).

Can you remember the AEFI reporting categories?

Take Home Messages

  * AEFI does not mean it is because of vaccine or vaccination process

   * All types of adverse events to be reported

   * Follow programme guidelines strictly to prevent

• Immunization error related reactions
• Anxiety related reactions

   * All clusters to be reported as serious irrespective of severity of clinical symptoms

AEFI Secretariat, Immunization Division

Comprehensive list of contact information of all the District Family Welfare Officers/District Immunization Officers.

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