Close contacts of COVID-19 positive cases in Thanh Xuan Trung district of Hanoi are moved into centralised quarantine in August 2021. (Photo: VNA/VNS)

These people, called F1, must strictly followed self-isolation regulations set by health authorities.

Their family members must also conduct group testing at least three times: the first day of quarantine, the seventh and fourteenth days.

The local Department of Health has been asked to map out a scenario of 100,000 COVID-19 cases given the increasing infection risk in the upcoming New Year holidays.