Date post: | 14-Jun-2015 |
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Health & Medicine |
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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
Sub Center /Outreach
Patient &Community
VaccineManufacturer
DCG(I)
MoHFWState FDA
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District Hospital/UHC/ OtherInstitutions
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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