Chapter 5 - Vaccine-Related Injury

Dr. Lyndon Llamado & KHG

Vaccines are important part of our civilized life. In a way, they are like medicines but in some ways there are important differences. Program and field managers need to know these to be able to promote immunization properly.

Because vaccines are promoted to healthy persons generally as a preventive intervention, there is a perception that these products as well as the immunization process should not cause any problems. In reality, adverse events following immunization do occur. Modern vaccines although safe and effective can be associated with mild to even life-threatening adverse reactions. They may be real adverse reactions from the product itself, programmatic errors, coincidental events, or injection site reaction. Some examples will be shared.

In these situations, it is important for the clinician or the field health worker to be able to address and manage such adverse events. Because if this is not handled properly, there can be serious impact on the public health program, loss of confidence in the health workers, the government, the product or possible hostility by the community. The management will necessarily include rapid assessment of the condition, careful investigation, practical advice to the parents and patients, and communication to important stakeholders such as the community leaders and the media. Some clinicians who eventually see AEFI sometimes do not give the correct interpretation of the events and often misinform the patients.

There are many ways to prevent AEFI. The program managers and health workers should come to terms on how to educate the community targeted for the immunization, and will need to include social preparation, and also how to prevent common programmatic errors. These will be discussed.

The important groups of people who should ensure vaccine safety include the drug industry, the drug regulators, the program managers of the EPI, the field health workers and the clinicians.

Types of Adverse Reactions:
1. Cutaneous:

Acute and long-term skin complications arising within the site of vaccination may occur. This may happen with either the initial vaccination or revaccination. This include development of benign tumors which may be in the form of exaggerated scarring which is the most common benign tumor reported, dermatofibroma, and nevus sebaceous. For the exaggerated scarring, these lesions in particular the hypertrophic scars, usually remain confined to the wound site and improve after a small number of intralesional steroid injections and do not recur. The same is not expected for keloids which usually extend beyond the original wound site and may appear months to years after the first scar formation. The nevus sebaceous is usually excised because it has a significant risk of developing coincident basal cell tumor. Malignant tumors may also develop from the vaccination site and these include basal cell carcinoma, malignant melanoma, squamous cell carcinoma fibrohistiocytic tumors and fibrosarcoma. These lesions have been observed both with the scars from the primary vaccination and revaccination. For small pox vaccination, basal cell carcinoma is the most commonly reported lesion. Skin dyspigmentationnd has also been reported and it is suggested that these lesions should be routinely monitored for changes in size, color and appearance as these changes may suggest a malignant transformation. Other vaccines associated with cutaneous scarring at the injection site include Bacillus Calmette-Guerin (BCG) and vaccinia. Clinicians and other health care providers should be aware of the various cutaneous lesions that may occur after vaccination and should inform the patients that skin lesions developing at the injection site other that smooth scar should be shown to health care providers.
2. Anaphylactic reactions

 

Considering that many different constituents of vaccines can result in immediate-type allergic reaction, vaccines in some instances may serve as an inciting allergen resulting to the development of anaphylactic reactions. Usually the symptoms of anaphylaxis develop within 5 to 30 minutes and less commonly up to 4 hours or even more. The symptoms can be divided based on the organ involved. For respiratory, dyspnea, bronchospasm, glossal/pharyngeal edema, hoarseness have been reported. Nose/eye symptoms include sneezing, red itchy watery eyes, rhinorrhea and nasal congestion. Hypotension, palpitations, light-headedness, loss of consciousness and tachycardia are the cardiovascular symptoms commonly described with pruritus, urticaria, angioedema and flushing for cutaneous complications.

Adverse events from only one organ system or even from more than one organ systems but developed four hours after the vaccine was given are less likely to be anaphylactic. However, every suspected adverse reaction should be approached in the same manner as far as evaluation and management is concerned.
3. Neurologic

 

Despite being reported in different literatures, there are still reports on the failure of the physicians or other health care providers to recognize the clinical manifestations of neurological complications associated with vaccination. This is definitely a concern since this complication may be associated with serious outcome. Adverse reactions involving the CNS may affect any and all parts of both the central and peripheral nervous system. These adverse events may come in different forms. An example of which is acute disseminated encephalomyelitis. Some of these vaccines reported to may have involvement of the nervous system are measles, varicella and rubella vaccines. In the case of live viruses like polio, an actual infection by the virus itself may happen. In cases of encephalitis, patients may present with fever, headache, vomiting, drowsiness, convulsions, meningeal signs or even coma.

A proposed mechanism behind the development of these adverse events include vasculopathy that can lead to vessel obstruction and ischemia and alteration of the blood-brain barrier that can lead to edema of the nervous system.

Even with the most advanced diagnostic tools we have right now there is no way of knowing who will have an adverse event after vaccination. Genetics background and previous immunological history however may be used to determine individual’s susceptibility. More often public health providers failed to ask about the history of vaccinations when they see patients presenting with signs and symptoms mentioned earlier because of the belief that adverse events do not happen with vaccinations.

Immunization is a successful and a cost effective way of preventing certain diseases. It can even be considered as one of the most important achievements of public health. However, clinicians and other public health care providers should always keep in mind that although modern vaccines are generally safe and effective it still can be associated with side effects which can range from mild to serious and life-threatening. Aside from this, we still do not have a vaccine that can be completely effective. Some persons who already received vaccinations may still develop the disease after exposure. Thus, the decision to use vaccines involves knowing the risk of the disease, the benefit of giving vaccination, cost effectiveness and the risk associated with its use. There is definitely a need to continuously re-evaluate vaccines indication and safety.

Things that need to be asked before vaccination include adverse event occurrence in the past to the same or any vaccines or its components. It is also worth asking for the history of allergy to food like eggs, chicken and gelatin which may be components of vaccines. If there was a history of allergic reaction to vaccine, clinicians and other health care providers should determine whether subsequent doses of the suspect vaccine or other vaccines with common components are still required. Checking for the antibody level may be helpful since if a patient has already mounted a sufficient antibody response, not giving further doses of the vaccines may be considered. It is important to know however, that persons with fewer than recommended doses may have a level of protective antibody which may not persist long. Lastly, it is important that clinicians and other health care providers should be aware and familiar with vaccines precautions and contraindications. Some of the common contraindications include severe hypersensitivity reaction to a previous dose of the same vaccine or to its components like anaphylaxis, and administration of live-virus vaccines like MMR, varicella and OPV in immunocompromised persons and pregnant women. General precaution is the presence of moderate or severe acute illness regardless of the presence or absence of fever. Knowledge of these things is definitely an important aspect of vaccination practice since application of these valid contraindications and precautions will definitely help minimize the occurrence of vaccine-related adverse reactions.


References:

1. Kelso JM. Immediate-type allergic reactions to vaccines. Up to date, version 14.3. August 2006.

2. Peter Georges. “Immunization Practices.” In Nelson Textbook of Pediatrics 17th Edition, edited by RE Behrman, RM Kliegman and HB Jenson. Elsevier’s Health Sciences, Philadelphia, Pennsylvania, 2004.

3. Poser CM. Neurological Complications of Vaccinations. [Online] available http://www.mercola.com, January 16, 2007.

4. Waibel KH, Walsh DS. Smallpox vaccination site complications. International J of Dermatology 2006, 45: 684-688.

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