Explaining mumps, isolation and the MMR strategy — OSCE

Candidate instructions (8-minute station)

You are the paediatric registrar in the clinic. A 7-year-old child has a PCR-confirmed diagnosis of mumps after three days of fever and bilateral parotid swelling, during a community outbreak. The child is recovering well and is fully vaccinated with two MMR doses. At home there is the child's aunt, who is 30 weeks pregnant, and an immunocompromised grandparent receiving chemotherapy. [3]

Your tasks are: [2]

1. Explain the diagnosis of mumps and what the illness will look like over the coming days, in plain language. [3]
2. Explain the isolation and school-exclusion plan, and why it matters even though the child is recovering. [2]
3. Explain why the pregnant aunt and the immunocompromised grandparent need prompt review and advice, and what that involves. [4]
4. Address the mother's question of why a fully vaccinated child caught mumps at all. [3]

You are not expected to prescribe for the aunt or grandparent yourself — flag that the grandparent needs same-day review by their oncology team because live MMR vaccine is contraindicated during chemotherapy and the aunt's immune status needs checking. [4]

Examiner prompt to the actor (mother)

"But she's had all her needles — both MMR doses — how can she have mumps? And she's getting better now, so does she really need to stay home from school? You're telling me my pregnant sister and my father on chemo need to be looked at — but they're not even sick. Is that really necessary?" [2]

Marking domains

• Frame and explanation (3): explains mumps and its likely course (parotitis settles over a week, with supportive care) in plain, reassuring language; names that the child is recovering and is not in danger now; sets the expectation that there is no specific drug — management is supportive and the real work is stopping spread. [3]
• Isolation and public-health plan (3): explains clearly that the child should stay home and avoid the aunt and grandparent until five days from the onset of parotitis swelling have passed, because the danger is transmission to the vulnerable contacts, not the child's own recovery; explains that mumps is notifiable and that public health may be in contact. [2]
• Protecting the high-risk contacts (3): explains that the pregnant aunt (live MMR contraindicated in pregnancy; mumps is not teratogenic like rubella but acute infection matters) and the immunocompromised grandparent (cannot have live MMR, depends on the immunity of others, needs same-day oncology review) are exactly the contacts we protect; frames the need to check their immune status and review them promptly. [4] [3]
• Communication (1): acknowledges the mother's surprise without defensiveness, uses plain language, checks understanding, and does not overwhelm. [3]

Model answer — the explanatory script

"Thank you for coming in. The test has come back, and it is mumps. The good news is that your daughter is over the worst of it and is recovering well; the swelling and the discomfort will settle over the next week with simple pain relief, fluids and a soft diet, and she's not in any danger now." [3]

"Now I want to explain three things — why she caught it despite being fully vaccinated, why she needs to stay home for a few more days, and why I'm worried about your sister, who's pregnant, and your father, who's on chemotherapy." [3]

"First, the vaccine. Your daughter's two MMR doses have absolutely done their job — they made this illness milder than it would otherwise have been, and that matters. But the mumps part of the vaccine doesn't last for life; its protection slowly fades over the years after the second dose. So even a fully vaccinated child can catch it, and the same fading protection in older teenagers and young adults is exactly why mumps keeps circulating in outbreaks like the one in your community. It doesn't mean the vaccine failed — it means the protection wanes over time." [3]

"Second, staying home. Even though your daughter is feeling better, she can still pass mumps on for a while. We keep her home and away from other children — and especially from your sister and your father — until five days have passed from when the swelling first started. That's the point at which she's no longer very contagious. It's not about her own recovery now — it's about not passing it to someone it could really hurt." [2]

"Third — and this is the most important part — your sister and your father. Your sister is 30 weeks pregnant. Mumps in pregnancy isn't known to harm the baby the way some other viruses can, which is reassuring, but we still want to check that she's protected, because she can't have the live mumps vaccine while she's pregnant — that's given after the baby is born if she turns out not to be immune. So we'd want her reviewed promptly to check her status." [4]

"Your father, on chemotherapy, is the one I'm most concerned about. His immune system is weakened by the treatment, so mumps could be much more serious for him, and — unlike your sister and your daughter — he cannot have the live mumps vaccine at all while he's on chemo. He depends on the people around him being immune. So I'd like him seen the same day by his oncology team, so they can assess his risk and his immunity and advise on what to do. We don't want to wait and see with him." [4] [3]