Vaccination in pregnancy — structured SAQ (15 marks)

(a) The four routinely recommended vaccines (5 marks)

One mark each for the first four (vaccine + timing + every-pregnancy), one mark for the overall principle. ^[4]

• Influenza (inactivated): any stage of each pregnancy, seasonal. Repeated every pregnancy.^[1]
• Pertussis (dTpa): 20 to 32 weeks gestation (ANZ/ATAGI). Repeated every pregnancy.^[2]
• RSV (Abrysvo, bivalent prefusion F): from 28 weeks gestation (ANZ), single dose, seasonal. Each pregnancy (where in season).^[3]
• COVID-19: per current ATAGI/ACOG guidance. Recommended in pregnancy.^[5]
• Principle: pertussis and RSV are given each pregnancy because antibody wanes between pregnancies and each infant needs a fresh antibody load transferred close to birth.^[4]

(b) Mechanism and timing rationale (3 marks)

One mark for the dual mechanism, one for IgG transfer physiology, one for the timing rationale. ^[4]

• Dual mechanism: maternal vaccination protects the mother directly (active immunity) and the infant via passive transfer of maternal antibody.
• IgG transfer: maternal IgG crosses the placenta via the neonatal Fc receptor (FcRn); transfer is minimal early and accelerates sharply in the third trimester, so a term infant is born with antibody concentrations that often exceed the mother's.
• Timing rationale: pertussis (20 to 32 weeks) and RSV (28 to 36 weeks) are timed for the late second to third trimester so there is enough time for a robust maternal antibody response and maximal transfer before birth. Vaccinate too early and antibody wanes before peak transfer; too late and the infant is born before transfer is complete.^[4]

(c) Contraindicated vaccines and why (3 marks)

One mark for naming them, one for the type, one for the rationale. ^[4]

• Live-attenuated vaccines contraindicated in pregnancy: MMR, varicella, BCG, live-attenuated influenza (LAIV), and yellow fever (unless risk unavoidable).
• These are live-attenuated vaccines — the organism replicates.
• Rationale: theoretical risk of fetal infection from the replicating organism. Documented harm is rare, but the precaution stands. If a live vaccine is given inadvertently, reassure and document — termination is not recommended for the vaccine alone.^[4]

(d) Rubella-seronegative management (4 marks)

One mark for NOT giving MMR in pregnancy; one for the postpartum plan; one for breastfeeding/avoidance counselling; one for documenting and the rationale. ^[4]

• Do NOT administer MMR during pregnancy — it is live and contraindicated. (The reflex error is to give it; do not.)
• Defer MMR to the postpartum period — administer it before discharge from hospital.^[4]
• Counsel: MMR is safe in breastfeeding; advise the woman to avoid pregnancy for one month after the dose.
• Document the seronegative status and the postpartum plan. Rationale: primary rubella infection in early pregnancy causes congenital rubella syndrome, so immunity matters and the postpartum catch-up is essential.^[4]