


2/They didn't just quarantine close contacts of infected, but all hospital visitors & their close contacts (F2s) were provided quarantine support: room and board. Contacts of F2s (F3s) & Contacts of F3s (F4s) were even asked to self-isolate: https://wwwnc.cdc.gov/eid/article/27/1/20-2656_article
3/Aggressive tracing/quarantine in Vietnam isn't unique to this outbreak. As @findingsen writes, once case is identified, all contacts in prior week are identified and quarantined. Those individuals' contacts are identified and asked to self-isolate.
https://globalasia.org/v15no3/cover/vietnams-pandemic-success-is-a-lesson-for-the-world_sen-nguyen:
https://globalasia.org/v15no3/cover/vietnams-pandemic-success-is-a-lesson-for-the-world_sen-nguyen: