Hanoi, Jan 2 : Authorities in Vietnam have tightened health regulations after five more Omicron cases were detected in Ho Chi Minh City, bringing the total infections of the type to 20, local media reported. All these people were immediately quarantined upon arrival on December 20-25, 2021, Xinhua news agency quoted the local media as saying citing the Ho Chi Minh City Centre for Disease Control. Their samples were sent for gene sequencing and the result confirmed that the specimens were positive for the Omicron variant. They are now in stable health conditions and their tests results turned negative after 5-7 days, according to the report. All 305 passengers travelling on flights with these Omicron variant cases have been quarantined in line with regulations of health authorities and have tested negative for the virus. The municipal administration is implementing Omicron response measures including closely monitoring arrivals from overseas, taking them to quarantine sites as regulated, and conducting genetic sequencing tests and contact tracing for positive cases. Since the onset of the pandemic in early 2020, Vietnam has reported 1,746,092 confirmed Covid-19 cases and 32,610 deaths. /IANS