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World Health Organization Global Training Network Programme

UNDERSTANDINGUNDERSTANDING

VACCINE REACTIONS (2) VACCINE REACTIONS (2)


PART 2PART 2

Vaccination of high-risk groups

Contraindications to vaccination

Adverse events associated with particular vaccines

Pathogenesis of serious adverse reactions


IMMUNIZATION OF SPECIAL POPULATIONSIMMUNIZATION OF SPECIAL POPULATIONS

5 dosesYYTetanus toxoid

N (need studies)YYellow fever

As for uninfectedYYHepB

6 and 9 monthsY (depends)YMeasles

0, 6, 10, 14 weeksY (IPV if available)YOPV

6, 10, 14 weeksYYDTP

BirthNYBCG

Optimal timing SymptomaticAsymptomaticVaccine

WHO/ UNICEF recommendations for vaccination of HIV-infected children and women of childbearing age


CONTRAINDICATIONSCONTRAINDICATIONS

True contraindications are rare

Current serious febrile illness delay vaccine administration

History of severe AEFI after previous dose

Evolving neurological disease avoid whole cell pertussis vaccine

(e.g. uncontrolled epilepsy)

Type 1 hypersensitivity to egg - avoid yellow fever & influenza but can use vaccines made in chick fibroblasts

Symptomatic HIV avoid BCG and yellow fever

WHO Immunization Policy 1996



Anaphylactic reaction to neomicin, streptomycin or polymyxin B

IPV

Immunodeficiency, or immunodeficient household contact*

OPV

Encephalopathy within 7 days of administrationDTP

Anaphylactic reaction to vaccine or vaccine constituentSevere febrile illness

All vaccines

ContraindicationVaccine

* Risk benefit assessment when administered to HIV positive individuals

Adopted from Plotkin pg 66-67



Anaphylactic reaction to common baker’s yeastHepatitis B

Anaphylactic reaction to egg, immunodeficiencyYellow fever

NoneHib

Anaphylaxis, pregnancy, immunodeficiency*MMR

ContraindicationVaccine

* Risk benefit assessment when administered to HIV-positive individuals

Adopted from Plotkin pg 66-67


ANAPHYLAXISANAPHYLAXIS

Type 1 hypersensitivity reaction

Circulatory failure

Bronchospasm +/- laryngospasm/laryngeal oedema

respiratory distress

May include pruritis, flushing, angioedema, seizures, vomiting, abdominal cramps & incontinence

Occurs in previously sensitized individuals


ANAPHYLAXISANAPHYLAXIS

Reported less from developing countriesLess sensitization?

Less reporting?

Anaphylaxis is rare (1/1 000 000 vaccinations)

Fainting is common

Untrained staff may misdiagnose fainting/dizzinessfor anaphylaxis or vice versa

Administration of adrenaline in a faint may bedangerous

PROMPT MANAGEMENT IS VITAL!


ADVERSE EVENTS ASSOCIATEDADVERSE EVENTS ASSOCIATED WITH SPECIFIC VACCINES WITH SPECIFIC VACCINES

WHO case definitions are used here

Lack of standardized case definitions in the literaturee.g. fever

The Brighton collaborationdeveloping case definitions for AEFI

promoting global implementation of these definitions

[email protected]://brightoncollaboration.org


SEIZURESSEIZURES

Particularly associated with measles and DTP vaccination (pertussis component)

febrile seizures Temp >38afebrile seizures Temp normal

Febrile seizures more common with pertussisAn association with non-febrile seizures has not been proven


ADVERSE REACTIONS TO BCG ADVERSE REACTIONS TO BCG

Disseminated BCGwidespread infection, 1-12 months after BCG

usually in immunocompromised individual

confirm by isolation of Mycobacterium bovisBCG strain

treat with antituberculous regimen including Rifampicin and Isoniazid

Osteitis/osteomyelitisinfection of the bone with M bovis BCG strain

management as above


ADVERSE REACTIONS TO BCG ADVERSE REACTIONS TO BCG

Suppurative lymphadenitisoccurs within 2-6 months of BCG vaccination

case definition

1 lymph node> 1.5 cm in size/draining sinus over a lymph node

usually occurs in the axilla, on the same side as innoculation

Managementheals spontaneously over monthsonly treat if sticking to skin or drainingsurgical drainage and local installation ofantituberculous drugsystemic Rx is ineffective


ENCEPHALOPATHY AND ENCEPHALITISENCEPHALOPATHY AND ENCEPHALITIS

Possibly associated with measles & pertussis vaccine

Case definition of encephalopathy2 out of 3 of

seizuresalteration of consciousness lasting for one day or moredistinct change in behavior for one day or more

Temporal relationshipwithin 48 hrs with DTPwithin 7-12 days after measles or MMR


ENCEPHALITIS AND MEASLES VACCINATIONENCEPHALITIS AND MEASLES VACCINATION

An analysis of claims for encephalitis following measles vaccine in the USA found clustering of events 8-9 days after vaccination (Wetbel 1998, Duclos 1998)

This supports, but does not prove, thepossibility that measles vaccine was causative

Risk is less than 1 case per million


TIMING OF VACCINATIONSTIMING OF VACCINATIONS

>2 killed antigens

killed and live antigens

>2 live antigens

None can be given simultaneously/at any interval

None (except cholera andyellow fever)

4 weeks, if not administered simultaneously (except OPV can be given any time before, after/with MMR and oral typhoid


MANAGEMENT OF ANAPHYLAXISMANAGEMENT OF ANAPHYLAXIS

Restore respiratory and cardiovascular function

SQ adrenaline: counteract bronchoconstriction and

vasodilation

Crystalloids - restore intravascular volume & prevent

shock

Establish and maintain airway

Corticosteroids to prevent “late-phase” reaction

Aminophylline as adjunctive for bronchospasm

Antihistamines not effective as primary therapy


TOXIC SHOCK SYNDROMETOXIC SHOCK SYNDROME

A one-year-old child died within 12 hours of receiving measles vaccine. It was reported as a possible anaphylaxis because of its rapidonset. Investigation found that the vaccine used was likely to have been reconstitutedsome days prior to this particular use.

Cause: Non sterile injection: NOT ANAPHYLAXIS!!!


BCG ADVERSE REACTIONSBCG ADVERSE REACTIONS

CaseAn outbreak of lymphadenitis three months after BCG immunization was traced to a switch to a differentstrain of vaccine. The investigation also highlighted a number of programme errors (vaccines not properlyreconstituted, and injections not given intradermally).

Cause: Vaccine reaction compounded by programme errors


ESTIMATED AEFI RATES FOLLOWING ESTIMATED AEFI RATES FOLLOWING CHILDHOOD VACCINESCHILDHOOD VACCINES

Vaccine

BCG

OPV

Measles

DTP

Estimated rate of serious reactions

1/1000 to 1/50 000 doses

1/3 million doses for 1st dose OPV

1/1million doses

1/750 000

WHO web site - Dealing with adverse events - 2/19/99

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