Previously, a 28-year-old Vietnam Airlines flight attendant was identified as the source of transmission in HCMC's latest Covid-19 outbreak, according to VNExpress.

Through contact tracing, the city identified three other infectees: a teacher who had visited the attendant when the latter was quarantined at home, the teacher’s nephew, and one of his students.

Thousands of people, including teachers and students who’d come into indirect contact with the four patients, were asked to quarantine themselves at home and their samples were taken for testing.

The flight attendant had returned from Japan on November 14 and was quarantined for four days at a Vietnam Airlines facility in Tan Binh District. He breached rules and visited another quarantine area, where he contracted the virus from a colleague who had returned from Romania.

Two doctors in protective gear stand outside Cu Chi field hospital in HCMC's Cu Chi District. Photo: VNExpress/Quynh Tran.

After two tests returned negative, he was allowed to go home and isolate himself. But he violated the rules of self-isolation and had contact with his mother and two friends, including the teacher who stayed with him for a few days.

The flight attendant also left home to eat out and attend classes at a university, VNExpress added.

He was suspended from his job and faces possible dismissal, while Vietnam Airlines would be inspected for compliance with Covid-19 prevention regulations, quarantine processes, and supervision at quarantine facilities.

HCMC police opened a criminal investigation into his breach of Covid-19 quarantine protocols.