Vaccine Booking System Design (Mock Interview + Slots & Fairness)
Visual Problem Diagram
Scenario
A public program must verify eligibility under changing regional rules, expose appointment inventory honestly, and survive thundering herds when new cohorts qualify—without double-booking slots or leaking sensitive records. The interview blends workflow, inventory, compliance, and ops more than a typical CRUD app.
Design a system for vaccine (or general immunization) eligibility verification and appointment booking at national scale, including spikes when new cohorts become eligible.
Constraints
User identity verification (level appropriate to problem); rule-based eligibility check; search appointments by location/time; book, cancel, reschedule; reminders; admin updates to rules and supply
Correctness of eligibility and slot counts; fairness; availability during thundering herds
Tens of millions of users; millions of bookings; regional rule variance