Appendix 6: Definitions of adverse events following immunisation

Please note: due to continuous updates being made to the Immunisation Handbook, the page number on the electronic version will not always match the hard copy version.


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Notify any events that the reporter considers serious and which may be related to the vaccine or vaccines administered. See Section 1.5.2, Adverse events following immunisation.

Abscess

Occurrence of a fluctuant or draining fluid-filled lesion at the site of injection, with or without fever.

• Bacterial: purulent collection.
• Sterile abscess: no evidence of bacterial infection.

Acute flaccid paralysis [diagnosis must be made by a physician]

Acute onset of flaccid paralysis of one or more limbs following any vaccine.

Allergic reaction (generalised)

A non-anaphylactic, generalised reaction characterised by 1 or more symptoms or signs of skin and/or gastrointestinal tract involvement WITHOUT respiratory or cardiovascular involvement.

(NB. See also ‘Anaphylaxis’).

Anaphylaxis

A rapidly evolving generalised multi-system allergic reaction characterised by 1 or more symptoms or signs of respiratory and/or cardiovascular involvement AND involvement of other systems such as the skin or gastrointestinal tract.

• Respiratory: difficulty/noisy breathing, swelling of the tongue, swelling/tightness in the throat, difficulty talking/hoarse voice, wheeze or persistent cough.
• Cardiac: loss of consciousness, collapse, pale and floppy (babies), hypotension.

Arthralgia

Joint pain without redness or swelling.

Arthritis

Joint pain with redness and/or swelling.

Brachial neuritis

Pain in arm causing persisting weakness of limb on side of vaccination.

Death

Any death of a vaccine recipient temporally linked to vaccination, where no other clear cause of death can be established.

Disseminated BCG

Disseminated infection occurring after BCG vaccination and confirmed by isolation of Mycobacterium bovis BCG strain.

Encephalopathy [diagnosis must be made by a physician]

Encephalopathy is an acute onset of major neurological illness temporally linked with vaccination and characterised by any 2 or more of the following 3 conditions:

• seizures,
• severe alteration in level of consciousness or mental status (behaviour and/or personality) lasting for 1 day or more, and/or
• focal neurological signs which persist for 1 day or more.

Encephalitis [diagnosis must be made by a physician]

Encephalitis is characterised by the above-mentioned symptoms and signs of cerebral inflammation and, in many cases, CSF pleocytosis and/or virus isolation.

Extensive limb swelling

Swelling of the limb, with or without redness, which:

• extends from the joint above to the joint below the injection site, or beyond a joint (above or below the injection site), or
• results in the circumference of the limb being twice the normal size.

Faint

See ‘Vasovagal episode’.

Fever

Only very high fever should be reported, eg. >40.5^oC.

Guillain-Barré Syndrome (GBS) [diagnosis must be made by a physician]

Acute onset of rapidly progressive, ascending, symmetrical flaccid paralysis, without fever at onset of paralysis and with or without sensory loss. Cases are diagnosed by cerebrospinal fluid (CSF) investigation showing dissociation between cellular count and protein content.

Hypotonic–hyporesponsive episode (shock, collapse)

The sudden onset of pallor or cyanosis, limpness (muscle hypotonia), and reduced responsiveness or unresponsiveness occurring after vaccination, where no other cause is evident such as a vasovagal episode or anaphylaxis. The episode usually occurs 1 to 48 hours after vaccination and resolves spontaneously.

Injection site reaction (severe)

Reaction (redness and/or swelling) at site of injection which:

• persists for more than 3 days AND is associated with ongoing symptoms such as pain or an inability to use the limb (see ‘Brachial neuritis’ above), and
• does not fulfil the case definition for extensive limb swelling (see ‘Extensive limb swelling’ above), or
• requires hospitalisation.

Intussusception [diagnosis must be made by a hospital physician]

The invagination of a proximal segment of bowel into the distal bowel lumen.

Lymphadenitis (includes suppurative lymphadenitis)

Occurrence of either:

• at least 1 lymph node, 1.5 cm in diameter or larger, or
• a draining sinus over a lymph node.

Meningitis [diagnosis must be made by a physician]

Acute onset of major illness with fever and often neck stiffness/positive meningeal signs (Kernig, Brudzinski) and with CSF pleocytosis.

Nodule

A discrete or well demarcated soft tissue mass or lump that is firm and is at the injection site in the absence of abscess formation, warmth and erythema.

Orchitis

Swelling with pain and/or tenderness of testes.

Osteitis

Inflammation of the bone due to BCG vaccination.

Osteomyelitis

Proven bacterial infection of bone.

Parotitis

Swelling and/or tenderness of parotid gland or glands.

Rash

Severe or unusual rash.

Screaming (persistent)

The presence of crying which is continuous and unaltered for longer than 3 hours.

Seizure

Witnessed sudden loss of consciousness and generalised, tonic, clonic, tonic-clonic, or atonic motor manifestations.

• febrile seizures: with fever ≥38.5^oC,
• afebrile seizures: without fever,
• syncopal seizures: syncope/vasovagal episode followed by seizure(s).

Sepsis

Acute onset of severe, generalised illness due to bacterial infection and confirmed by positive blood culture.

Subacute sclerosing panencephalitis [diagnosis must be made by a physician]

Degenerative central nervous system (CNS) condition with laboratory confirmation of abnormal serum and CSF measles antibodies.

Syncope

See ‘Vasovagal episode’.

Thrombocytopenia

Platelet count <50 x 10⁹/L.

Toxic shock syndrome [diagnosis must be made by a physician]

Abrupt onset of fever, vomiting, watery diarrhoea and shock within a few hours of vaccination as can be associated with other conditions listed here.

Vaccine-associated paralytic poliomyelitis

See ‘Acute flaccid paralysis’.

Vasovagal episode (syncope, faint)

• Episode of pallor and unresponsiveness or reduced responsiveness or feeling light headed AND
• occurring while vaccine being administered or shortly after (usually within 5 minutes), AND
• bradycardia, AND
• resolution of symptoms with change in position (supine position or head between knees or limbs elevated).

(See Table 1.5.1 to distinguish from anaphylaxis).

Other severe or unusual events

Any unusual event that does not fit into any of the categories listed above, but is of medical or epidemiological interest, should be reported with a detailed description of the clinical features.

Report by telephone to State or Territory Health Department or notify by the blue card to ADRAC (see Section 1.5.2, Adverse events following immunisation.

Note: The Brighton Collaboration is an international group considering definitions of adverse events following immunisation. Its website is: http://www.brightoncollaboration.org.