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What is the BCG Vaccination Scar? The BCG vaccination scar is a common occurrence after receiving the Bacillus Calmette-Guérin (BCG) vaccine, which protects against tuberculosis (TB). Most individuals, especially infants who receive the vaccine in countries where TB is prevalent, develop a small scar on their upper left arm.

Why Does the BCG Vaccine Leave a Scar? The BCG vaccine is a live attenuated vaccine that triggers an immune response. After administration, a localized reaction occurs at the injection site, leading to a small lesion that later heals and forms a scar. This is a normal reaction indicating that the vaccine has stimulated an immune response. The process typically follows these stages:

• • Redness and swelling: Shortly after the vaccine is administered, a small red bump may appear at the injection site.

• • Formation of a pustule: Within 2-3 weeks, the bump may develop into a small ulcer with pus.

• • Healing and scarring: Over a period of weeks to months, the ulcer heals, leaving behind a small scar, usually 3-5mm in diameter.

The scar is about 3-5mm in diameter on the left hand due to BCG tuberculosis vaccination.

Do All BCG Vaccinations Leave a Scar? While approximately 90% of individuals develop a scar after BCG vaccination, about 10% do not. The absence of a scar does not necessarily mean the vaccine was ineffective. Studies suggest that even without a visible scar, individuals may still have developed immunity to tuberculosis.

Factors That Influence the BCG Vaccination Scar Several factors affect whether a scar forms and how prominent it may be:

• • Individual immune response: Some people naturally have stronger immune responses, leading to more pronounced scarring.

• • Injection technique: Proper intradermal injection ensures effective vaccine administration and may influence scar formation.

• • Skin type and healing ability: Different skin types may react differently, leading to variations in scar size and visibility.

Is It a Problem If There Is No Scar After BCG Vaccination? Not having a scar after BCG vaccination is not necessarily a cause for concern. Research has shown that a lack of scarring does not always indicate vaccine failure. Therefore, routine revaccination or antibody testing is not recommended unless there is a clinical reason to do so.

How to Care for the BCG Vaccination Site To promote proper healing and reduce complications, follow these guidelines:

• • Keep the injection site clean and dry to prevent infection.

• • Avoid applying ointments, oils, or herbal remedies to the area.

• • Do not scratch or squeeze the lesion as this may lead to scarring or secondary infection.

• • Allow the scab to fall off naturally to avoid unnecessary irritation.

When to Seek Medical Attention Although most BCG vaccination scars heal without complications, some reactions may require medical evaluation:

• • Persistent swelling, pain, or redness beyond the expected healing period.

• • Excessive pus or fluid drainage.

• • Enlarged lymph nodes near the injection site.

• • Unusual or spreading skin reactions.

Final Thoughts The BCG vaccination scar is a natural outcome of the immunization process and is commonly seen in individuals vaccinated against tuberculosis. While not everyone develops a scar, the presence or absence of one does not necessarily indicate vaccine effectiveness. Proper post-vaccination care and monitoring for any abnormal reactions can help ensure a smooth healing process. If you have concerns about the BCG vaccination or its effects, consult a healthcare professional for guidance.