The new patient, a Vietnamese citizen returning from Germany on November 19, tested positive for SARS-CoV-2 while staying in quarantine in the northern province of Quang Ninh.
As of 6pm on November 21, Vietnam had gone 80 straight days free of community infection of the coronavirus.
Among those still under treatment, 11 have tested negative for SARS-CoV-2 once, nine twice and five thrice.
Meanwhile, 15,582 people who had close contact with COVID-19 patients or returned from pandemic areas are under health monitoring nationwide.