Table 2.

Immediate component-mediated reactions and associated vaccines in children.

Component	Function in Vaccines	Relevant Vaccines	Allergic Reactions	Ref.
Gelatin	Stabilizer	MMR and varicella	Anaphylaxis and urticaria	[24,25]
Egg protein (albumin)	Residual medium and stabilizer	MMR, influenza, and yellow fever	Anaphylaxis	[10,29]
Milk protein (casein)	Medium nutrient	DTaP	Anaphylaxis	[34]
Thimerosal	Preservative	Influenza and Td	Local reaction	[35,36]
Aluminum	Adjuvant	DTaP, Hib, hepatitis A/B, HPV, Japanese encephalitis, meningococcal, pneumococcal, and Tdap	Local reaction	[10]
Neomycin	Antimicrobial	DTaP, hepatitis A, influenza, MMR, polio, and varicella	Anaphylaxis	[38]
Phenoxyethanol	Preservative	DTaP, influenza, polio, and Tdap	Local reaction	[39]
Latex	Pharmaceutical closure	DTaP, hepatitis A/B, influenza, meningococcal, rotavirus, Tdap, Td, and yellow fever	Anaphylaxis and urticaria	[40,41]
Yeast	Medium nutrient	DTaP, hepatitis B, HPV, meningococcal, and pneumococcal	Anaphylaxis	[10,42]
Dextran	Medium nutrient and stabilizer	MMR a and rotavirus	Anaphylaxis	[43]
Polyethylene glycol	Surfactant of mRNA	COVID-19	Anaphylaxis	[44,45,46]

^a MMR vaccines containing dextran have been withdrawn from the market. MMR, measles–mumps–rubella; DTaP, diphtheria–tetanus–acellular pertussis; Td, tetanus–diphtheria; Tdap, tetanus-diphtheria-acellular pertussis; Hib, Hemophilus influenzae type b; HPV, human papillomavirus.