Definition

Adverse events following immunization (AEFI) refer to immunization-related medical events, including vaccine reactions, injection reactions, or procedural mistakes until a causal relationship is determined. Immunization is a preventive measure against infectious diseases achieved through vaccination. Vaccines train the body to combat viruses and bacteria that can cause disease.

The term 'vaccine' has its roots in the Latin word 'vacca,' meaning cow. Coined by Edward Jenner for the prevention of smallpox, vaccination, and immunization are related terms but carry distinct meanings. Vaccination involves training the body to develop immunity by exposing it to weakened viruses through vaccines. On the other hand, immunization is the body's natural process to protect against diseases for which one has been vaccinated.

Immunization can be administered from infancy through college, with government immunization programs typically following specific intervals to ensure timely vaccinations for every child. The primary goal of immunization is to prevent or reduce the severity of diseases. While it may not offer complete protection, immunization can significantly decrease disease severity. Even if exposed to certain diseases, immunized individuals will likely experience milder symptoms with very low risk of complications.

Vaccination works by introducing a small amount of weakened or killed viruses or bacteria into the body, stimulating the immune system to produce antibodies against specific diseases or triggering other processes to enhance immunity. Some vaccines require multiple doses or boosters to maintain effectiveness.

Ideally, Children should receive most of their initial vaccines within the first two years of life. For example, the CDC advises that the first dose of the measles, mumps, and rubella (MMR) vaccine be given at 12 months or later, with the second dose administered between 4 and 6 years old, before starting elementary school. By the age of 15 months, children generally receive about 10 vaccines, with further vaccinations recommended between 15 and 16 years of age.

Pediatricians may adjust the vaccination schedule for children with chronic conditions or weakened immune systems. Common vaccines include hepatitis B (given at 1 to 2 months of age), Rotavirus, diphtheria, tetanus, Haemophilus influenzae type B, pneumococcal, and poliovirus (administered at 2, 4, and 6 months).

Vaccination itself is generally safe for children, with common side effects, including pain at the injection site and low-grade fever. Severe side effects are rare. It's important to discuss any concerns about vaccination risks and side effects with your pediatrician.

Causes

The side effects of immunization result from the body's immune response, which is a defense mechanism aimed at producing antibodies. These side effects can vary, but often include fever and pain at the injection site.

Risk factor

Vaccination is the process of inducing immunity in the body by stimulating the immune system to develop protection against specific diseases. It's important to note that vaccinating a child when they are unwell can pose an increased risk. Therefore, it is not recommended to administer vaccines when the child's health condition is compromised.

Symptoms

Some common side effects that may occur after vaccination are usually mild and include:

• Pain, swelling, or redness at the injection site
• Mild fever
• Chills or feeling cold
• Fatigue
• Headache
• Joint and muscle pain
• Vomiting

There's no need to panic if you experience any side effects after vaccination; simply contact your doctor for advice. Post-vaccination symptoms can manifest rapidly or gradually, including local, systemic, and central nervous system reactions or other symptoms.

Usually, the earlier an adverse event following immunization (AEFI) occurs, the more severe the symptoms may be. Observation for specific events may extend from 42 days to 6 months. Common symptoms include mild fever, pain, and swelling at the injection site, typically resolving within 2-3 days with or without medication.

It's important to understand that not everyone experiences AEFIs after vaccination. Mild symptoms are more common than serious inflammatory or allergic reactions to the vaccine.

Diagnosis

The doctor will assess your child's health and readiness for vaccination. If the doctor determines that your child is unwell, they may recommend postponing the immunization. They will conduct a physical examination of the child. If necessary, they may perform further tests to diagnose and provide appropriate treatment for any symptoms that arise from post-immunization events.

Management

If your child experiences side effects from immunization, you can take several steps to help them feel better. Ensure they get enough rest, provide fever-reducing medication, and encourage them to drink plenty of water. If there is pain at the injection site, encourage movement and arm usage, and consider applying a cold compress with a damp cloth. 

Medication will be tailored to the severity of symptoms, with mild symptoms possibly improving without medication, while moderate to severe symptoms may require medical attention.

Complications

Complications from immunization are generally rare, but in some cases, unwanted effects can occur, ranging from mild to severe. Severe allergic reactions, although uncommon, may include symptoms such as difficulty breathing, swelling in the face and throat area, rapid heartbeat, redness all over the body, dizziness, and weakness. 

If you experience such allergic reactions, you must seek immediate medical attention by contacting the nearest hospital. Additionally, inform your doctor and the immunization provider if you experience side effects that are not resolved.

Prevention

There is no specific prevention for adverse events following immunization. It's important to ensure your child is in good health before vaccination. If your child is unwell or has certain health conditions, such as autoimmune disorders, it is advisable not to proceed with vaccination until approval is obtained from a doctor. Immunization aims to strengthen your child's immune system, so administering vaccines when the child is unwell may lead to undesirable effects.

When to see a doctor?

Before immunizing your child, discuss the type of vaccine and the timing of immunization with your doctor. If any unwanted side effects occur after vaccination, contact your doctor immediately. For severe symptoms such as facial swelling and difficulty breathing, seek prompt treatment at the hospital.

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