adverse events following immunization, aefi
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Adverse Events Following Immunization, AEFI. A brief presentation on the adverse events following immunization, monitoring for AEFIs and taking actions when events occur. Adverse Events Following Immunization, AEFI. - PowerPoint PPT PresentationTRANSCRIPT
WHO/V&B/AVI
Adverse Events Following Immunization, AEFI
A brief presentation on the adverse events following immunization, monitoring for AEFIs and taking
actions when events occur
WHO/V&B/AVI
Adverse Events Following Immunization, AEFI
Adverse events following immunization are events or reactions observed following immunization. Some of these events may be due to the vaccine, some due to error in the administration of the vaccine
There is no vaccine that is 100% safe & without any risks
Such events may range from mild side effects to life-threatening, but rare, illnesses
WHO/V&B/AVI
AEFI
Mild Reactions Mild reactions following immunization
are common They include pain & swelling at the site
of injection, fever, irritability, malaise They are self-limiting, hardly requiring
even symptomatic treatment But it is important to reassure parents
about such events so that they know about it
WHO/V&B/AVI
AEFI
Rare, more severe reactions Severe reactions are rare Such reactions include seizures,
thrombocyto-paenia, hypotonic hyporesponsive episodes, persistent inconsolable screaming
In most cases they are self-limiting and lead to no long-term problems
Anaphylaxis, while potentially fatal, is treatable without any long-term effects
WHO/V&B/AVI
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
WHO/V&B/AVI
AEFIAvoiding 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
WHO/V&B/AVI
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
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AEFI
Steps in AEFI surveillance Detection and reporting Investigation Data analysis Corrective and other actions Evaluation
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AEFIDetection 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 abscessesAll cases of BCG lymphadenitisAll deaths suspected to be related to
immunizationAll hospitalisation suspected to be related to
immunization
WHO/V&B/AVI
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
WHO/V&B/AVI
AEFIInvestigation
AEFI investigation will attempt to confirm or propose alternative diagnosis of the
reported eventidentify the specifications of the vaccine incriminatedexamine the operational aspects of the programmeidentify 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
WHO/V&B/AVI
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)
WHO/V&B/AVI
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.
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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.
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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
WHO/V&B/AVI
AEFIData 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 supportIf patient hospitalised, tests may confirm diagnosisTesting vaccines often yield doubtful answersSend case investigation report with vaccine for test
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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.
WHO/V&B/AVI
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
WHO/V&B/AVI
AEFICorrective 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
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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.
WHO/V&B/AVI
AEFIEvaluation
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 aretimeliness, completeness, accuracy of the systemswiftness with which response was effected when
a trigger event was reportedappropriateness of actions takenpotential for strengthening of immunization
system
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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