Transcript Adverse Events Following Immunization, AEFI

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
BCG
Hib
Onset
Interval
2-6 months
1-12 months
1-12 months
Rates per
million doses
100 to 1000
1 to 700
2
0-1 hour
0 to 2
1-6 weeks
5-12 days
15-35 days
0-1 hour
5
333
33
1 to 50
Vaccine associated paralytic polio (VAPP)
Persistent (>3 hrs) inconsolable crying
Seizures
Hypotonic, hyporesponsive episode
Anaphylaxis
Encephalopathy
4-30 days
0 -24 hours
0 - 3 days
0-24 hours
0 - 1 hour
0 - 3 days
Post-vaccination encephalitis
Allergic/anaphylaxis
WHO/V&B/AVI
7-21 days
0-1 hour
1.4 to 3.4
1000 to 60000
570
570
20
0 to 1
400 to 4000 (in
infants <6 m)
5 to 20
Reaction
Suppurative lymphadenitis
BCG osteitis
Disseminated BCG-it is
Nil known
Anaphylaxis
Hepatitis B
Guillain-Barrè Syndrome (plasma derived)
Febrile seizures
Thrombocytopaenia
Measles/MMR Anaphylaxis
OPV
DTP
Yellow Fever
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
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
WHO/V&B/AVI
AEFI
Steps in AEFI surveillance
Detection and reporting
Investigation
Data analysis
Corrective and other actions
Evaluation
WHO/V&B/AVI
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 hospitalisationWHO/V&B/AVI
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
WHO/V&B/AVI
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
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.
WHO/V&B/AVI
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 convulsionsonset 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.
WHO/V&B/AVI
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
Data analysis
AEFI
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
WHO/V&B/AVI
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
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
WHO/V&B/AVI
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
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
WHO/V&B/AVI
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
WHO/V&B/AVI