Vaccine contraindications, precautions and adverse events — branching viva

Stem

The examiner moves from definitions to an acute AEFI, then to immunocompromise and a false-contraindication trap. [1] [2]

Branch 1 — Definitions

Examiner: What is the difference between a contraindication and a precaution? [1]

Strong answer: A contraindication means the risk of a serious adverse reaction is high enough that the vaccine should not be given. A precaution means increased risk, possible reduced response, or diagnostic confusion — usually defer or seek advice rather than permanently withhold. Give one example of each and one false contraindication. [1]

Branch 2 — Clinic decision

Examiner: Well infant with mild URTI; parent fears autism after MMR in a relative. [1] [4]

Strong answer: Mild illness is not a true contraindication. Autism family history is a false contraindication. Vaccinate if otherwise eligible. Cite large evidence against causal MMR–autism association and document counselling. [1] [4]

Branch 3 — Anaphylaxis

Examiner: Wheeze, urticaria and hypotension 8 minutes after injection. [2]

Strong answer: This is anaphylaxis until proven otherwise. IM adrenaline anterolateral thigh first. Call for help, oxygen, fluids if shocked, repeat adrenaline if needed. Do not lead with antihistamine. Then observe/admit, report AEFI, and contraindicate the culprit product. [2] [5]

Branch 4 — Live vaccines and transplant/IEI

Examiner: Child early after HSCT, and another child with suspected SCID. [3] [7]

Strong answer: Live vaccines are restricted until immune reconstitution and specialist clearance after HSCT. SCID: no rotavirus, no BCG, broader live-vaccine avoidance. Inactivated vaccines may still be indicated with timing advice. Household contacts should be protected without using transmissible OPV where relevant. [3] [7]

Branch 5 — Rare AEFI and surveillance

Examiner: Parent quotes an internet list of VAERS reports as proof vaccines are unsafe. Another infant has possible intussusception after rotavirus. [5] [6]

Strong answer: Passive systems detect signals and include coincidental events; they do not alone prove causation. For suspected intussusception, treat the surgical emergency first, then report and counsel the small excess risk against large disease benefit using balanced evidence. [5] [6]

Examiner extras

• Egg allergy is not an automatic ban on influenza vaccine for most children. [8]
• Vasovagal syncope ≠ anaphylaxis. [2]
• True contraindications are rare; missed opportunities are common. [1]