Explaining pertussis, isolation and prophylaxis — 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 pertussis after a two-week paroxysmal cough with a whoop and post-tussive vomiting. The child is fully vaccinated and recovering. At home there is a 4-week-old newborn sibling and the child's aunt, who is 32 weeks pregnant, is currently staying with the family. [8]

Your tasks are: [1]

1. Explain the diagnosis of pertussis and what the illness will look like over the coming weeks, in plain language. [1]
2. Explain the isolation and school-exclusion plan, and why it matters even though the child is recovering. [10]
3. Explain why the newborn sibling and the pregnant aunt need prompt assessment and prophylaxis, and what that involves. [10]
4. Address the mother's question of why a fully vaccinated child caught pertussis at all. [1]

You are not expected to take a full contact-tracing history yourself or to prescribe doses for the newborn without senior review — flag that the newborn needs same-day assessment because apnoea can be the first sign in an infant. [8]

Examiner prompt to the actor (mother)

"But she's had all her needles — how can she have whooping cough? And she's getting better now, so does she really need to stay home from school? You're telling me the baby and my pregnant sister need antibiotics too — is that really necessary? They're not even coughing." [10]

Marking domains

• Frame and explanation (3): explains pertussis and its likely course (the cough may last weeks to months) in plain, reassuring language; names that the child is recovering and is not in danger now; sets the expectation that antibiotics shorten infectiousness rather than the cough. [1]
• Isolation and public-health plan (3): explains clearly that the child should stay home and avoid the newborn until five days of antibiotic are completed, because the danger is transmission to the vulnerable baby, not the older child's own recovery; explains that pertussis is notifiable and that public health may be in contact. [10]
• Protecting the high-risk contacts (3): explains that the newborn (too young to be fully vaccinated) and the pregnant aunt are exactly the contacts we protect — that prompt assessment and prophylactic antibiotics can prevent or attenuate disease, and that the newborn needs same-day review because apnoea can be the first sign in an infant; frames the aunt's pregnancy and maternal-Tdap as central to protecting her future baby. [10] [8]
• Communication (1): acknowledges the mother's surprise without defensiveness, uses plain language, checks understanding, and does not overwhelm. [1]

Model answer — the explanatory script

"Thank you for coming in. The test has come back, and it is whooping cough — pertussis. The good news is that your daughter is over the worst of it and is recovering well; the hard part is that the cough can linger for weeks, sometimes a couple of months, and that's normal for this illness, so don't be alarmed if it takes a while to fully settle." [1]

"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 the baby and your sister, who's pregnant." [1]

"First, the vaccine. Your daughter's vaccinations have absolutely done their job — they made this illness milder than it would otherwise have been, and that matters. But the whooping-cough part of the vaccine doesn't last for life; its protection slowly fades over the years. So even a fully vaccinated older child can catch it, and the same fading protection in adults and teenagers is actually why the illness keeps circulating. It doesn't mean the vaccine failed — it means we all need boosters as we get older, and it's exactly why we now recommend the whooping-cough vaccine in every pregnancy." [1]

"Second, staying home. Even though your daughter is feeling better, she can still pass it on for a while. We keep her home and away from other children, especially the baby, until she's had five full days of the antibiotic. That's the point at which she's no longer contagious. It's not about her own recovery now — it's about not passing it to someone it could really hurt." [10]

"Third — and this is the most important part — the baby and your sister. Whooping cough is most dangerous in babies under six months, because their airways are small and they can't handle it the way an older child can. Your baby is only four weeks old and isn't old enough yet to be fully protected by the vaccine, so we need to treat this very seriously. I'd like the baby seen today, and we'll give a short course of antibiotic to help prevent the illness taking hold, because in a tiny baby the first sign can be a pause in breathing rather than a cough. We do not want to wait and see." [10] [8]

"Your sister, being 32 weeks pregnant, is another priority. The whooping-cough vaccine in pregnancy passes protection from her to the baby she's carrying, so that baby is born already covered for those first months. We want to make sure she's protected now and that her own vaccine status in this pregnancy is up to date, and we'd offer her a preventive course of antibiotic too, so she doesn't bring it home to her own household. None of this is because they're sick now — it's to stop them getting sick, and especially to protect the babies." [8] [10]