Five among the new patients are Vietnamese citizens, including two returning from the UK on December 22, and three from Germany on December 18.
The sixth patient is a Brazilian expert who arrived from Qatar on December 24.
They tested positive for SARS-CoV-2 while staying in quarantine after arrival.
The same day, 22 COVID-19 patients were given the all clear, bringing the total recoveries to 1,303, while fatalities remained at 35.
Among patients still under treatment, eight have tested negative for SARS-CoV-2 once, eight twice and eight thrice.
A total 16,809 people are being quarantined nationwide, with 171 at hospitals, 15,672 at designated concentrated facilities and 966 at homes or accommodations.
