Allergies to vaccines in infants

Allergy to vaccines in infants: Myths and reality

The fear of allergic reactions is one of the most common reasons for refusing vaccination. It is important to clearly distinguish normal, expected reactions to a shot, which indicate the immune system is working, from genuine, extremely rare allergic reactions.

Normal reaction vs. allergic reaction

Normal (expected) reactions:

• Local: Redness, swelling, firmness and pain at the injection site. This is a sign of local inflammation where immune cells "meet" the vaccine components.
• Systemic: Fever, lethargy, drowsiness, temporary loss of appetite. This is also a normal immune response.

True allergic reactions:

These are immune reactions, usually immediate-type (IgE-mediated), to one of the vaccine components. They are extremely rare (1-2 cases per million doses).

• Hives or angioedema (Quincke's edema), occurring within minutes or hours after vaccination.
• Anaphylactic shock: The most severe, but extremely rare reaction. That is why after any vaccination the child should be monitored by medical staff for 30 minutes.

Which components can cause an allergy?

Allergy develops not to the antigen itself (attenuated virus or bacteria), but to excipients: egg protein (in some flu vaccines), gelatin, yeast, antibiotics (neomycin). The presence of atopic dermatitis or food allergy in a child is not a contraindication to vaccination. For more details on the vaccination schedule, read the article "Vaccination calendar up to one year".