Screen before you vaccinate — vaccines and immunobiology

Station status

This is one MedVellum formative structured clinical encounter. The scoring, prompts and performance descriptions are educational feedback tools. They are not an official college station, timing, mark allocation, pass score or reproduced examination format. The encounter assesses the prevaccination screen, the live-versus-inactivated distinction, the four-week spacing rule, the rotavirus age limits, the premature-infant chronological-age rule, catch-up minimum intervals, and the recognition of anaphylaxis after a vaccine. [1] [11]

Candidate instructions

You are the paediatric registrar in a general paediatrics clinic seeing a family for vaccination. Run the prevaccination screen, decide which vaccines are safe for each child, apply the live-vaccine spacing rule, confirm the rotavirus age limits, build a catch-up plan for the sibling with an incomplete record, and address the family's concerns. Speak directly to each child and the parent. State what you would assess, ask, or give; do not perform painful manoeuvres on the actor. [1] [3]

Room setup and observable starting state

The encounter. The family is in the clinic for routine vaccination. Aria is two months old, born at thirty weeks, and is due her scheduled infant vaccines. Her older brother Tom is four, recently arrived from overseas, with an immunisation record that is incomplete and partly undocumented. Their adolescent cousin Priya, twelve, is present and is about to start methotrexate for juvenile idiopathic arthritis, with her second measles-mumps-rubella dose overdue. The candidate is asked to vaccinate safely across all three. [1]

Simulation safety. The children remain seated throughout and are never examined painfully. Cards or the assessor supply the immunisation records and the rotavirus age detail. The parent does not obstruct the consultation. [1]

Actor cues

Parent actor

• Begin with, "They're all due their needles today, but I'm a bit worried." If asked what worries her, answer: "Aria was so tiny — is it safe? Tom's record is a mess from moving. And Priya's about to start that arthritis medicine." [3]

Adolescent cousin actor

• Responds to questions about pregnancy possibility: "There's no chance I'm pregnant." If the candidate asks appropriately and respectfully, confirm a negative pregnancy test or no possibility, clearing the live vaccine. [2]

Assessor cues and clinical data

Release findings as the candidate reaches each step. Reward the screen, the chronological-age rule, the spacing rule, the rotavirus limits, and the catch-up principle. [1]

Step 1 — The premature infant

Expected strong behaviour: state that Aria is vaccinated by chronological age with full doses and no reduction, because the immune response is adequate and the risk of vaccine-preventable disease is high; give the scheduled infant vaccines due at two months; and, where the infant is still an inpatient, arrange the oral rotavirus vaccine in the hospital setting with infection-control measures. [3]

Step 2 — The rotavirus age limits

The record shows Aria's rotavirus first dose is being given at two months. Expected strong behaviour: confirm the rotavirus age limits — first dose before fifteen weeks and the course complete by twenty-four weeks — and explain that the small intussusception risk rises with age, which is why the limits are strict. [5]

Step 3 — The catch-up sibling

Expected strong behaviour: state that Tom, with an unconfirmable record, is assumed non-immune and caught up using minimum intervals (commonly four weeks) without restarting the series; respect the minimum age for the first dose of each vaccine; apply the live-vaccine same-day-or-four-weeks rule; and write the plan down and share it with primary care. [1]

Step 4 — The adolescent starting immunosuppression

Priya is about to start methotrexate, and her second measles-mumps-rubella dose is overdue. Expected strong behaviour: complete the live vaccines before immunosuppression begins, because live vaccines are contraindicated once the child is significantly immunosuppressed; confirm there is no possibility of pregnancy before a live vaccine in an adolescent girl; apply the four-week spacing rule if more than one live vaccine is due; and arrange inactivated vaccines such as annual influenza alongside. [2] [11]

Step 5 — Anaphylaxis readiness

Expected strong behaviour: confirm the clinic has an adrenaline dose chart and a clear anaphylaxis plan; state that anaphylaxis declares itself within minutes and is treated with intramuscular adrenaline into the anterolateral thigh at the weight-appropriate dose with the child positioned flat; and describe the post-vaccination observation and the adverse-event reporting pathway. [1]

Marking domains

Debrief prompts

• What is the single most important screening question before a live vaccine, and how did you apply it to each of the three children?
• How did you decide the rotavirus dose was within its age limits, and what would you have done if Aria had been older?
• Where in this encounter was the risk of a live-vaccine spacing error highest, and how did you avoid it?