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Health Sciences Authority

Adverse events following immunisation (AEFI)

Find out what are the considerations of reportable adverse events following immunisation.

Last updated 13 March 2026

The following list of suggested reportable AEFIs is meant as a guide and by no means exhaustive.

In general, healthcare professionals are advised to report all events following immunisation as long as no other clear cause has been identified. This would include events whereby a causal link to a vaccine has not been established.

The onset time interval is provided only as a general guiding principle and will depend on the antigen and adverse reaction, as well as patient factors.

List of reportable AEFIs

Reportable AEFI

Onset time interval

  • Anaphylactoid reaction (acute hypersensitivity reaction)

  • Anaphylaxis

  • Persistent inconsolable screaming (more than 3 hours)

  • Hyptonic-hyporesponsive episode

  • Toxic shock syndrome

Within 24 hours to 48 hours of immunisation

  • Severe local reaction

  • Sepsis

  • Injection site abscess (bacterial or sterile)

Within 7 days of immunisation

  • Seizures, including febrile seizures

  • Encephalopathy

Within 14 days of immunisation

  • Acute flaccid paralysis

  • Branchial neuritis

  • Intussusception

  • Thrombocytopenia

Within 3 months of immunisation

  • Lymphadenitis

  • Disseminated BCG infection

  • Osteitis or osteomyelitis

Between 1 and 12 months after BCG immunisation

  • Death

  • Hospitalisation

  • Disability

  • Any other severe and unusual events suspected to be associated to the vaccine

No time limit