Written by Dr. Shilpa Reddy T, MBBS, DNB Pediatrics, IDPCCM — Consultant Paediatrician & Paediatric Critical Care Specialist, Tiny Totz Kids Clinic, Puppalaguda, Hyderabad
Almost every parent who brings their child for a vaccination at Tiny Totz Clinic asks the same thing before leaving: what should I expect after this, and when should I call you? It is the right question.
Vaccines work by presenting the immune system with something it needs to recognise and respond to. The immune system's response — inflammation, activation, and memory-cell formation — is exactly the same as its response to a real infection. The local redness, the low-grade fever, the irritability are not problems. They are the immune system doing exactly what the vaccine asked it to do. The discomfort of a mild vaccine reaction is the price of the protection being built.
At the injection site
Fever
A low-grade fever — up to 38.5°C — within 24 to 48 hours of vaccination is the most common systemic reaction. Manage with weight-appropriate paracetamol if the child seems distressed. Fever should settle within 48 hours. If fever persists beyond 48 hours — contact your paediatrician. At that point it may be a coincidental separate viral infection rather than purely vaccine-related.
Irritability and crying
Babies are frequently fussier than usual for 24 to 48 hours. Skin-to-skin contact, extra feeding, and comfort are the appropriate responses. Inconsolable crying beyond 3 hours should be reported.
Drowsiness and loss of appetite
Some babies sleep more than usual — a normal response to mild immune activation. Ensure they are woken for feeds at appropriate intervals. Mild appetite reduction for 24 hours is common — continue feeding on demand.
DPT / Pentavalent / Hexavalent vaccines
More local reactions than most other vaccines — a firm, sometimes large lump at the injection site, fever, and irritability are more pronounced. The lump can persist 2 to 4 weeks — not a concern unless it becomes hot, actively spreading, or develops pus.
MMR vaccine (given at 12 months)
A mild fever and faint rash may appear 7 to 12 days after MMR — not immediately after, but more than a week later. This is a normal delayed immune response to the measles component. Brief, mild, does not require treatment beyond paracetamol if the child seems uncomfortable.
Rotavirus vaccine (oral drops)
Mild loose stools for a day or two after administration are normal. The rotavirus in the vaccine is live-attenuated and causes a very mild transient gut response.
Chickenpox vaccine
A small blister-like rash — typically fewer than 50 spots — may appear 7 to 21 days after the varicella vaccine. Mild vaccine-strain chickenpox response. Child is minimally contagious during this period — stay home from school until spots crust over.
ℹ Anaphylaxis — severe allergic reaction — is very rare (approximately 1 in a million doses) but can occur within 15 to 30 minutes of any vaccine. This is why I ask families to remain at the clinic for 15 to 20 minutes after vaccination. Signs: sudden pallor, limpness, respiratory distress, widespread rash within minutes. If any of these occur after leaving the clinic — go to the nearest hospital emergency immediately.
Myth: Vaccines cause autism
False. The original 1998 study claiming a link was proven to be fabricated, retracted by The Lancet in 2010, and the researcher lost his medical licence. Multiple large-scale studies involving millions of children have found no link between any vaccine and autism.
Myth: Too many vaccines at once overwhelm the immune system
False. The number of antigens in all childhood vaccines combined is a tiny fraction of what the immune system processes daily. Simultaneous administration is safe, endorsed by IAP and WHO.
Myth: The child already had the disease, so the vaccine isn't needed
Natural immunity after some diseases is incomplete or wanes. For diseases where the vaccine provides equal or superior immunity, vaccination is still recommended. Discuss the specific disease with your paediatrician.
Every vaccination includes a pre-vaccination check, a discussion of what to expect, and a 15 to 20 minute observation period after the shot. If you have any concern after a vaccination — however small — call or WhatsApp +91 7815933120. It is always better to ask. Monday to Friday, 6:00 PM to 9:00 PM, Puppalaguda, Hyderabad.
1. Should I give paracetamol before the vaccination to prevent fever?
No. Pre-emptive paracetamol before vaccination may blunt the immune response. Give it only if the child develops fever or discomfort after — at the standard weight-based dose.
2. My child had a high fever after the last DPT shot. Should I skip the next dose?
Generally, no. A high fever after DPT is a known reaction but is not a contraindication to future doses. Discuss the reaction with your paediatrician before the next visit. The risk of missing the dose is far greater than the risk of a repeat fever reaction.
3. The injection site lump has been there for 3 weeks. Is that normal?
A firm, non-painful, non-growing lump at a DPT injection site can persist 4 to 6 weeks — a normal inflammatory response. If the lump is increasing in size, becoming painful, or developing discharge — it needs to be examined.
4. Can my child have vaccination if they have a cold?
Minor illness — mild cold, runny nose, no fever — is not a contraindication to vaccination. Proceed to avoid falling behind schedule. If the child has a fever above 38°C on the day — reschedule until the fever resolves.
