What is a fever after vaccination in infants?

Fever after a vaccination?
Don’t panic — it’s actually a normal response in many babies!

Why does it happen?
Vaccines “train” the immune system to recognize and fight real infections later. This training can trigger a mild immune reaction — like a low-grade fever — which means the body is responding just as it should.

When can it occur?
⏰ Within 24–48 hours after most routine vaccines (like DTaP, pneumococcal)
⏳ Or 5–12 days later after live vaccines (like MMR)

What should parents do?
✔️ Keep your baby comfy and well-hydrated
✔️ Dress them lightly — avoid overheating
✔️ You may give infant paracetamol (if advised)
✔️ Observe behavior, not just the thermometer!

When to contact your doctor?
❗ Fever over 39°C (102.2°F)
❗ Lasting longer than 48 hours
❗ Baby is very sleepy, irritable, not feeding, or if you feel unsure

Fever after vaccination is common, mild, and temporary — and it shows your little one is building protection for the future!

Yours, Dr Aleksandra 🦋

Dr Aleksandra Gajecka
Pediatrician in Malta

• Treatment of sick children
• Protective baby and childhood vaccinations
• Health check-ups
• Care for the development of healthy children
• Counseling in children’s physical and mental development
• Online consultations regarding the possibilities of effective diagnostics
• Preliminary diagnostics and referring patients to specialists for in-depth diagnostics
• Issuing documents and certificates needed for nurseries, schools and educational institutions