Vaccine Types & Contraindications

A child who is immunocompromised receives a live vaccine and develops the disease it was meant to prevent. Knowing which vaccines are live — and who cannot receive them — prevents this catastrophe.

Vaccines fall into two broad categories that drive every contraindication decision: live attenuated and inactivated (killed or subunit). Live attenuated vaccines contain weakened but replicating organisms — MMR, varicella, rotavirus, intranasal influenza (LAIV), and oral polio. Because the organism replicates, live vaccines are contraindicated in immunocompromised clients (children on high-dose corticosteroids ≥2 mg/kg/day or ≥20 mg/day of prednisone for ≥14 days, chemotherapy, HIV with severe immunosuppression, or congenital immunodeficiency). Live vaccines are also contraindicated in pregnancy. Inactivated vaccines — DTaP, IPV, Hep B, Hep A, PCV13, inactivated influenza — cannot replicate and are safe for immunocompromised children. True contraindications across all vaccines include anaphylaxis to a vaccine component or a prior dose. A moderate-to-severe acute illness with fever is a precaution warranting deferral, but mild illness with low-grade fever is NOT a reason to withhold vaccination. Egg allergy considerations apply to influenza and yellow fever vaccines; current ACIP guidelines state that egg allergy of any severity is no longer a contraindication or precaution for standard influenza vaccines. Gelatin allergy is relevant for MMR and varicella. A history of intussusception contraindicates rotavirus vaccine.

Key Distinctions

Don't confuse a true contraindication (anaphylaxis to a prior dose) with a precaution (moderate febrile illness) — precautions allow vaccination once the acute issue resolves. Students often classify all injectable vaccines as inactivated; intranasal influenza is live while the injectable form is inactivated — the route signals the type. Mild illness, current antibiotic use, and family history of adverse reactions are NOT valid reasons to defer vaccines.

Clinical Pearl

"Live vaccines Live in you" — they replicate, so never give them to a child whose immune system can't fight back. If it replicates, it's restricted.