Systemic Allergic Contact Dermatitis After Formaldehyde-Containing Influenza Vaccination

Area of Science:

• Dermatology
• Allergology
• Vaccinology

Background:

• Systemic contact dermatitis (SCD) is a delayed hypersensitivity reaction.
• It occurs when a sensitized individual is re-exposed to an allergen systemically, leading to a widespread cutaneous eruption.
• Formaldehyde is a known sensitizer that can be present in various products, including vaccines.

Observation:

• A 48-year-old male presented with explosive dermatitis after receiving an influenza vaccine.
• Patch testing revealed strong positive reactions to formaldehyde and formaldehyde-releasing allergens.
• This clinical presentation suggested a diagnosis of systemic contact dermatitis.

Findings:

• Literature review identified cases of SCD from formaldehyde in aspartame and thimerosal-containing vaccines.
• However, no prior cases of SCD specifically linked to formaldehyde in influenza vaccines were found.
• This case represents a novel association between influenza vaccine-associated formaldehyde and SCD.

Implications:

• Clinicians should consider SCD in patients developing dermatitis after vaccination with formaldehyde-containing products.
• Formaldehyde sensitization is a potential, albeit rare, complication of vaccine administration.
• Further investigation into vaccine excipients and their allergenic potential is warranted.