Introduction
An adverse event following immunization (AEFI) is defined as any untoward medical occurrence following immunization which does not necessarily have a causal relationship to the vaccine.
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Vaccines used in the national immunization program are relatively safe and effective. However, no vaccine is perfectly safe. Therefore, adverse reactions may occur. This study aimed to investigate the understanding and experience of Adverse Event Following Immunization (AEFI) among healthcare workers and Routine Immunization (RI) officers.
To address this concern, an interrater study of causality assessment for serious AEFIs was conducted in April 2017 to evaluate the reliability (i.e. the degree to which an assessment tool produces consistent results between country evaluators) of the methodology and to compare the manual AEFI causality assessment method with the electronic method. The study was conducted using serious AEFI cases from India and Zimbabwe. Each country had 2 assessing teams and each team had 4 persons with expertise in paediatrics, epidemiology, pharmacovigilance and public health.
Attribution of causality to AEFI, especially those considered severe, of public importance, and programmatically disruptive, are critical for ensuring vaccine safety. In 2005, WHO published an aide-mémoire to a systematic, standardized causality assessment process for serious AEFI (including clusters), providing a method for individual causality assessment to be used by staff of national immunization programmes, regulatory authorities and pharmacovigilance or surveillance departments.5 After 7 years, several limitations had been identified during its use in the field, including: the need for more detailed guidance on the elements required to perform the assessment of causality, confusion over the terms used to classify the likelihood of association of the event to the vaccine, and the incomplete use of parameters for establishing causal association.
The new WHO proposed method allows the National Committees for AEFI case review and causality assessment to screen serious cases reported by their surveillance system for completeness and quality of information, ensuring the objectiveness of the assessment. Cases deemed incomplete are directed towards additional case investigation and review. A checklist containing the elements of causality assessment was included to guide the Committee or the assessor to gather the evidence needed for case review, and when completed allows the application of an algorithm that helps determine if the AEFI could be consistent or inconsistent with an association with the immunization, or is deemed indeterminate due to lack of evidence. A repository of all AEFI cases sorted through this new document is considered critical and recommended to allow for future signal detection and determining the need for additional epidemiological studies.
When and how to report an AEFI
Timely AEFI reporting is essential to detect possible changes to the safety profile of all vaccines. The key criteria for reporting an AEFI are temporal association and has no other clear cause at the time of reporting. A causal relationship does not need to be proven.
Vaccine providers contribute to vaccine safety by reporting AEFI which allows further investigation of adverse events, but does not mean that an observed event was caused by either vaccine or immunization.
How AEFIs are monitored
AEFI reports are received at the health regions from multiple sources: physicians, nurses, pharmacists and public health.
Recommendations are made by the regional Medical Officer of Health, who conveys it to the vaccine recipient’s immunization provider. The data are shared with Health facilities (Health), which reviews them before forwarding to PHAC. Health may, in coordination with the concerned RHA and in consultation with other local experts as well as with PHAC, perform any further investigation that may be required.
Personnel in PHAC’s Vaccine Safety Section screen all submitted reports, ensure they are entered into the database and coded using standard international coding terminology. Reports are monitored with special attention to serious or unusual events that could signal a concern regarding vaccine safety.
An AEFI is an untoward medical event which follows immunisation and does not necessarily have a causal relationship with the administration of the vaccine. The adverse event may be an unfavourable or unintended sign, abnormal laboratory finding, symptom or disease. Most adverse events for COVID-19 vaccines are non-serious and mild, and resolve within the first 2-3 days after vaccination. For example, mild headache, pain and redness at the injection site, slight fever, etc. Not all suspected adverse events, whether minor or serious, are caused by the vaccine. It is possible that the timing of the suspected adverse event may be coincidental to the vaccination.
TYPES OF AEFI
The World Health Organization (WHO) categorizes adverse events following immunization (AEFI) as;
>serious AEFI
^ Fever
^ Pain at the injection site
^ Difficulty breathing or swallowing
^ Extreme drowsiness
^ Gastrointestinal symptoms
^ Local reactions
^ Respiratory tract symptoms
^ Central nervous system symptoms
^ Rash
>non-serious. Serious AEFI.
^Muscle or joint pain
^Pain
^Redness
^Fatigue
^Nausea
Causes
You've outlined the various factors that can contribute to Adverse Events Following Immunization (AEFI). Let's break them down further:
Immunization Errors
1. *Improper handling*: Incorrect storage, transportation, or preparation of vaccines.
2. *Prescribing errors*: Incorrect vaccine selection or dosage.
3. *Administration errors*: Incorrect injection technique or route.
Vaccine Quality Defects
1. *Manufacturing defects*: Contamination, incorrect formulation, or faulty packaging.
2. *Expiration or degradation*: Using expired or degraded vaccines.
Anxiety-Related AEFI
1. *Hyperventilation*: Rapid breathing leading to dizziness or fainting.
2. *Syncope*: Fainting or loss of consciousness due to anxiety.
Coincidental Events
1. *Unrelated illnesses*: Conditions unrelated to the vaccine or immunization error.
2. *Environmental factors*: Exposure to environmental toxins or allergens.
Underlying Conditions
1. *Allergies*: Pre-existing allergies to vaccine components.
2. *Chronic conditions*: Underlying medical conditions, such as heart disease or diabetes.
Individual Genetic Makeup
1. *Genetic predisposition*: Individual genetic factors influencing immune responses.
2. *Variability in immune response*: Differences in how individuals respond to vaccines.
Prevention of AEFI
General Prevention Strategies
1. *Proper Vaccine Handling*: Store, transport, and prepare vaccines according to manufacturer instructions.
2. *Accurate Prescribing and Administration*: Ensure correct vaccine selection, dosage, and injection technique.
3. *Patient Screening*: Assess patients for underlying conditions, allergies, and potential interactions.
4. *Informed Consent*: Educate patients about vaccine benefits, risks, and potential AEFI.
Vaccine-Specific Prevention Strategies
1. *Vaccine Storage and Expiration Management*: Regularly check expiration dates and store vaccines properly.
2. *Vaccine Administration Technique*: Use proper injection technique and follow manufacturer guidelines.
3. *Dose and Schedule Management*: Ensure correct dosing and scheduling for vaccine series.
Patient-Specific Prevention Strategies
1. *Medical History Assessment*: Evaluate patients for underlying conditions, allergies, and potential interactions.
2. *Allergy Testing*: Conduct allergy testing for patients with suspected allergies to vaccine components.
3. *Monitoring for AEFI*: Closely monitor patients for signs of AEFI after vaccination.
Healthcare Provider Education and Training
1. *Vaccine Education*: Provide healthcare providers with up-to-date information on vaccines, AEFI, and prevention strategies.
2. *Immunization Technique Training*: Offer training on proper vaccine administration technique.
3. *AEFI Recognition and Management*: Educate healthcare providers on recognizing and managing AEFI.
Advices
Advice for Preventing and Managing Adverse Events Following Immunization (AEFI)
General Advice
1. *Consult a healthcare professional*: Before vaccination, consult a healthcare professional to discuss potential risks and benefits.
2. *Follow vaccination schedules*: Adhere to recommended vaccination schedules to minimize risks.
3. *Monitor for AEFI*: Closely monitor for signs of AEFI after vaccination.
Patient-Specific Advice
1. *Disclose medical history*: Inform healthcare providers about underlying medical conditions, allergies, and medications.
2. *Report concerns*: Inform healthcare providers about any concerns or symptoms after vaccination.
3. *Follow post-vaccination instructions*: Adhere to post-vaccination instructions provided by healthcare providers.
Healthcare Provider Advice
1. *Stay updated on vaccine information*: Stay current with the latest vaccine information, including potential AEFI.
2. *Assess patient risk factors*: Evaluate patients for potential risk factors, such as underlying medical conditions or allergies.
3. *Provide clear instructions*: Provide patients with clear instructions on post-vaccination care and AEFI monitoring.
Additional Resources
1. *National vaccine safety surveillance systems*: Utilize national vaccine safety surveillance systems for reporting and monitoring AEFI.
2. *Vaccine manufacturer guidelines*: Consult vaccine manufacturer guidelines for specific recommendations on vaccine administration and AEFI management.
3. *Peer-reviewed literature*: Stay informed about the latest research and findings on vaccine safety and AEFI.
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