adverse events following immunization, aefi

Adverse Events Following Immunization, AEFI

AEFI

WHAT IS AN AEFI?

AEFI IS A MEDICAL INCIDENT AFTER

AN IMMUNIZATION AND IS BELIEVED

TO BE CAUSED BY THE

IMMUNIZATION

BASICALLY TWO TYPES

AVOIDABLE AND UNAVOIDABLE

AEFI

MODERN VACCINES

ARE GENERALLY SAFE

NOT ENTIRELY WITHOUT RISK

BENEFITS FAR OUTWEIGH RISKS

AEFI

WHY MONITORING OF AEFI ARE

IMPORTANT ?

UPSETS PEOPLE

REFUSAL FOR FURTHER IMMUNIZATION

AEFI

CLASSIFICATION OF AEFI

VACCINE EFFECT

PROGRAMME ERROR

COINCIDENTAL

INJECTION REACTION

UNKNOWN

AEFI

THE USEFULLNESS OF MONITORING AEFI

TO IDENTIFY PROGRAMME ERRORS

IDENTIFY VACCINE DEFECTS

TAKE CORRECTIVE MEASURES

INCREASE IMMUNIZATION ACCEPTANCE

IMPROVE THE QUALITY OF SERVICES

AEFI

AEFI ARE DUE TO:

1 VACCINE

EVENT CAUSED OR PRECIPITATED BY THE VACCINE WHEN GIVEN CORRECTLY, CAUSED BY THE INHERENT PROPERTIES OF THE VACCINE

AEFI

2 PROGRAMME ERROR

EVENT CAUSED BY AN ERROR IN VACCINE:

PREPARATION

HANDLING

ADMINISTRATION

AEFI

3 COINCIDENTAL

EVENT THAT HAPPENS AFTER IMMUNIZATION BUT NOT CAUSED BY THE VACCINE – A CHANCE ASSOCIATION

AEFI

4 INJECTION REACTION

EVENT FROM ANXIETY ABOUT, OR

PAIN FROM THE INJECTION ITSELF

RATHER THAN THE VACCINE

5 UNKNOWN

THE CAUSE OF THE EVENT CANNOT

BE DETERMINED

AEFI

SURVEILLANCE

1. DETECTION AND REPORTING

2. INVESTIGATION

3. DATA ANALYSIS

4. CORRECTIVE ACTION

5. EVALUATION

AEFI

HOW CAN AEFI’S BE DETECTED?

WHAT MECHANISMS ARE AVAILABLE?

AEFI

LIST OF AEFI

1. LOCAL ADVERSE EVENTS

2. CNS ADVERSE EVENTS

3. OTHER ADVERSE EVENTS

AEFI

LOCAL ADVERSE EVENTS

1.INJECTION SITE ABSCESS

STERILE

BACTERIAL

AEFI

FORMATION OF A STERILE ABSCESS

1. WRONG ROUTE (SC INSTEAD OF DEEP IM)

2. NOT SHAKING THE VACCINE BOTTLE BEFORE

DRAWING IN TO THE SYRINGE

3. WRONG DOSE (LARGER DOSE)

AEFI

2. LYMPHADENITIS

AT LEAST ONE LYMPH NODE 1.5 CM IN SIZE OR DRAINING SINUS OVER LYMPH NODE 2 – 6 MONTHS AFTER BCG ON THE SAME SIDE AS INOCULATION

AEFI

3. SEVERE LOCAL REACTION

REDNESS AND/OR SWELLING AT THE SITE WITH ONE OR MORE OF THE FOLOWWING

1. SWELLING BEYOND JOINT

2. LASTING MORE THAN 3 DAYS OR

3. REQUIRES HOSPITALIZATION

AEFI

CNS ADVERSE EVENTS

1. ACUTE PARALYTIC POLIOMYELITIS

• WITHIN 4-75 DAYS

RESIDUAL PARALYSIS AFTER 60 DAYS OR DEATH

AEFI

2. GBS OCCURING WITHIN 30 DAYS

3. ENCEPHALOPATHYCASES OCCURING WITHIN 72 HOURS

AFTER VACCINATION

AEFI

4. ENCEPHALITISCASES OCCURING WITHIN 72 HOURS

5. MENINGITISWITHIN 1- 6 WEEKSSEIZURES – AFEBRILE

- FEBRILE

AEFI

OTHER ADVERSE EVENTS

1.ALLERGIC REACTION

2.ANAPHYLACTIC SHOCK

3.ARTHRALGIA

4.DISSEMINATED BCG-IT IS

5.HIGH FEVER

AEFIOTHER ADVERSE EVENTS(CONT)

6. HYPOTENSIVE EPISODE (SHOCK/COLLAPSE)

7. OSTEITIS/OSTEOMYELITIS

8. PERSISTENT SCREAMING

9. SEPSIS (SEVERE GENERALIZED ILLNESS

CONFIRMED BY BLOOD CULTURE)

AEFI

OTHER ADVERSE EVENTS(CONT)

10.TOXIC SHOCK SYNDROMEFEVER, VOMITTING AND WATERY DIARRHOEA- FEW HOURS AFTER IMMUNIZATION – OFTEN LEADING TO DEATH

Examples of types & frequency of AEFIs (in some common vaccines)

Vaccine ReactionOnset

IntervalRates per

million dosesSuppurative lymphadenitis 2-6 months 100 to 1000BCG osteitis 1-12 months 1 to 700Disseminated BCG-it is 1-12 months 2

Hib Nil knownAnaphylaxis 0-1 hour 0 to 2

Guillain-Barrè Syndrome (plasma derived) 1-6 weeks 5Febrile seizures 5-12 days 333Thrombocytopaenia 15-35 days 33Anaphylaxis 0-1 hour 1 to 50

OPV Vaccine associated paralytic polio (VAPP) 4-30 days 1.4 to 3.4Persistent (>3 hrs) inconsolable crying 0 -24 hours 1000 to 60000Seizures 0 - 3 days 570Hypotonic, hyporesponsive episode 0-24 hours 570Anaphylaxis 0 - 1 hour 20Encephalopathy 0 - 3 days 0 to 1

Post-vaccination encephalitis 7-21 days400 to 4000 (in infants <6 m)

Allergic/anaphylaxis 0-1 hour 5 to 20Yellow Fever

BCG

Hepatitis B

Measles/MMR

DTP

AEFI

• Avoiding Programme Errors– Use sterile needle & syringe for every injection– Reconstitute only with specific diluent– Discard reconstituted vaccines after six hours– Do not store drugs & other medicines in the same

fridge as the vaccines and diluents– Train & supervise health workers to ensure safe

injection practices– Monitor, Investigate and Act when AEFIs occur

AEFI

• Why monitor AEFI?– No vaccines are 100% safe and without any

risks– It is important to know the risks and how to

handle such an event when it occurs– Informing people correctly on AEFI helps keep

public’s confidence in the immunization programmes

– Monitoring AEFI also helps improve the quality of service

AEFI

• Steps in AEFI surveillance

– Detection and reporting

– Investigation

– Data analysis

– Corrective and other actions

– Evaluation

AEFI

• Detection and reporting– Every individual that administers an immunization

injection should know about AEFI– There should be a national system for detecting and

reporting of AEFI– At least the following should be included in the national

AEFI monitoring system- “trigger events”• All injection site abscesses• All cases of BCG lymphadenitis• All deaths suspected to be related to immunization• All hospitalisation suspected to be related to

immunization

AEFI

• Detection and reporting– The above basic categories act as “trigger”

mechanisms for further course of action– The national monitoring system should define the

flow of information and mechanisms for taking actions– While minor events may be recorded and reported as

a routine activity to be analysed only at periodic times, sudden, unexplained deaths or large scale hospitalisation or a cluster of events reported following immunisation warrants immediate investigation

AEFI

• Investigation– AEFI investigation will attempt to

• confirm or propose alternative diagnosis of the reported event

• identify the specifications of the vaccine incriminated• examine the operational aspects of the programme• identify whether it was an isolated event or a cluster of

events and, if a cluster, where the immunization was given and what vaccines were used

– Preliminary investigation may be carried out by the local health worker, but serious AEFIs or clusters of AEFIs should be investigated by special teams from district or central level

AEFI

• Investigation– Data on the patient(s); vaccine (lot number, expiry,

manufacturer, lab results if any), storage, reconstitution practice, diluent used, general disease information in the area, similar disease episodes in unimnunized persons in the same locality, etc. should be collected

– Collect samples of vaccines and diluents used (make sure vaccine sample collected are kept in the cold chain)

AEFI: An example of an AEFI investigation

• Background– It is reported that following a measles campaign in a

primary school in District X, several children had convulsions. It was widely rumoured that the measles injection was responsible for it

• Hypothesis– that the reported health event (convulsion) was an

AEFI following measles vaccination

• Define the case– You define your ‘case’ as any child in that primary school who

received measles injection on that particular day and had

convulsions.

AEFI: example contd..

• Case investigation– Line list all children, with age & sex, who had

received measles injection on that day– Find those that reported to have had convulsions– Find out all the details regarding the convulsions-

onset time after immunization, manner of convulsion, recovery following the convulsion, concomitant medications, fever, any other health problems. Determine the quality of the vaccine (expiry, storage), reconstitution, diluent, injection process, etc.

– Take samples of the vaccine vials used for lab testing– Scrutinise the stock entries, stock balance, etc.

AEFI: example contd..

– One child had an attack of fit half an hour after the immunization. Following this three other children had fainting spells in the same class. All recovered spontaneously although the child who had the first convulsion took longer to recover. Also, the first child sustained a minor cut on the forehead from the fall

– Next day, five more children called in sick on grounds that they had also attacks of fits after the school

AEFI• Data analysis

– Once the data is collected, it should be analysed as quickly as possible to determine whether the AEFI is

• Programme related (incorrect dose of vaccine, wrong site, wrong diluent, improper storage & handling, use of other medicines as diluent, etc.)

• Vaccine induced AEFI • Coincidental AEFIs (caused by something other than

vaccine or programme errors)• Unknown

– Laboratory support• If patient hospitalised, tests may confirm diagnosis• Testing vaccines often yield doubtful answers• Send case investigation report with vaccine for test

AEFI: example contd..

• Data Analysis– You find that the vaccine used has not expired, was well

maintained in the cold chain, correct diluent was used, – There was no evidence of contamination, the health workers

always discarded reconstituted vaccine at the end of the session.

– The medical history showed that the fits which the other children had were mere fainting spells, lasting only for a few moment, with spontaneous recovery. No subsequent attacks occurred

– The index child had a true convulsion. No fever or other illnesses at that time.

AEFI: example contd..

– However, going over the medical history of the child, the health worker recalled that last year the same child had an episode of convulsion for which he had provided treatment. He had advised that the parents should consult a medical or a neurological expert for further management. On questioning, it was found that the parents did not have the time or the money to do that and it was felt that it would resolve naturally

AEFI

• Corrective and other actions– Action must not wait for investigation to be completed– Treat the patient(s) as the first response– Communicate, inform the public, parents, media

people on the event, actions being taken & next steps– Once the investigation is completed, publicise the

results– Take corrective actions, where necessary– Training of health workers & supervision to prevent

avoidable AEFIs in future

AEFI: example contd..

• Conclusion– From the available information, and based on

the data analysis, you conclude that event was not an AEFI, but Coincidental.

– Following this, you will take time to explain to the parents, teachers and the community about the event, your investigation and your final conclusions.

AEFI

• Evaluation– Like any other surveillance systems, AEFI

surveillance must also be evaluated periodically to examine its usefulness and to modify it if necessary

– Issues to consider when evaluating a surveillance system are

• timeliness, completeness, accuracy of the system• swiftness with which response was effected when

a trigger event was reported• appropriateness of actions taken• potential for strengthening of immunization system

AEFI

An ounce of prevention is always better than a pound of cure. Good training & close

supervision of health workers, coupled with a functioning surveillance system for monitoring & reporting are the best

guarantee against the likelihood of an event occurring at all