राष्ट्रीय टीकाकरण सारणी के अनुसार जन्म के समय शिशु को नियमित रूप से कौन सा टीका लगाया जाता है?

A 5-year-old child is exposed to measles at school. The healthcare provider recommends administration of the measles vaccine within 72 hours. Which immunoprophylactic principle is being applied in this scenario?

Which route is most commonly used for administering standard vaccines under national immunization schedules?