Epidemiology & Prevention USMLE Step 1 Practice Question
A 7-year-old boy with acute lymphoblastic leukemia currently receiving chemotherapy presents to clinic with vital signs: BP 105/68, HR 92, RR 20, Temp 37.1°C, SpO2 98%. Recent labs show WBC 1.2K/μL and platelet count 95K/μL. He cannot receive live vaccines due to immunosuppression. His pediatrician emphasizes that high vaccination coverage among classmates is especially important for protecting him from measles exposure, with no prior measles immunity documented. Which epidemiologic principle best explains this protective effect?
Answer choices
- ACross-reactive immunity
- BPassive immunity
- CArtificial active immunity
- DHerd immunityCorrect answer
- ETertiary prevention
- FVector-borne transmission prevention
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