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INVESTIGATING ADVERSE EVENTS FOLLOWING IMMUNIZATION

AEFI

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

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

OVERVIEW

Definitions Detecting and reporting AEFIs

Conducting a case investigation

Analysing and assessing AEFI data

Taking action

Measuring outcome

WHAT IS AN ADVERSE EVENT FOLLOWING IMMUNIZATION (AEFI)?

A medical incident that takes place after an immunization, causes concern, and is believed to be caused by immunization

Vaccine reaction - caused by vaccine’s inherent properties

Programme error - caused by error in vaccine preparation, handling, or administration

Coincidental - happens after immunization but not caused by it (a chance association)

Injection reaction - anxiety or pain of injection not vaccine

Unknown - cause cannot be determined

CLUSTER

>=2 cases of the same adverse event following immunizations related in time, geography or in the vaccine administered

Why is it important to monitor for clustering?

POTENTIAL OBJECTIVES FOR IMMUNIZATION SAFETY SURVEILLANCE SYSTEM

Detect, correct, and prevent programme errors Identify problems with vaccine lots or brand Prevent false blame from coincidental events Maintain confidence by properly responding to

parent/community concerns while increasing awareness (public and professional) about vaccine risks

Generate new hypotheses about vaccine reactions that are specific to the population

Estimate rates of occurrence on AEFI in the local population, compared with trial and international data (particularly for new vaccines being introduced)

DETECTING AND

REPORTING AEFIs

DETECTING AND REPORTING AEFIs

Decide on

WHICH events to be included in

surveillance?

WHO should be involved in detection?

WHAT is the route of reporting?

WHEN should AEFIs be reported?

HOW should reporting occur?

WHAT happens next?

AEFI

Detection and reporting Every individual that administers an immunization injection

should know about AEFI

The following are events need to be reported and investigated immediately All deaths suspected to be related to immunization All hospitalisation suspected to be related to

immunization Any event where vaccine quality is suspected

AEFI

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

mechanisms for further course of action

While minor events may be recorded and reported as a routine activity in monthly reports 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

Reporting of Severe AEFI

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Patient &Community

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CHANNELS AND TIMELINE FORREPORTING SERIOUS AEFI CASES

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 from district or state/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 unimmunized 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)

FORMS USED FOR INVESTIGATION

The reporting of the minor events is done on monthly basis in the form 9 of RCH

The reporting for severe cases is done using First Information report (FIR) in 48 hrs

Followed by Preliminary investigation report (PIR) within 7 days

And a Final report in form of Detailed investigation report (DIR) within 90 days

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: 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

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

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

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

IDENTIFYING CAUSE OF AEFI CLUSTER

Yes Yes

YesYesYes Yes

No NoNoNo

NoNo

Programme error, coincidental or vaccine problem/ “unknown”

Manufacturer error, batch problem, or

transport/storage error

Programme error

Coincidental event Vaccine reaction

Cluster of AEFIs

All cases from only one facility (same

lot used at others)?

Coincidental event

Programme error orvaccine problem

All cases got same vaccine

or lot?

Known vaccine

reaction?

Similar illness in others who didn’t get

vaccine?

Similar illness in

others who didn’t get vaccine?

Rate of reaction

within theexpected

rate?

CAUSALITY ASSESSMENT

?Adverse Event

CASE REPORTS - ONLY ONE PART

Disease +(AEFI)

Disease –(not AEFI)

Exposure +(vaccine) a b

Exposure –(no vaccine) c d

Risk evaluation requires a 2x2 table of exposures and outcomes Case reports represent only one cell of table Risk of event from vaccine = a*d/b*c

CONCLUSIONS

Immunization safety is likely to become increasingly important

Need to develop system which detects investigates takes action (including communication) measures outcome of action