"Patient 1213," 22, got back to Vietnam from the African nation on October 20 on Vietnam Airlines flight VN8 that touched down in Van Don airport in northern Quang Ninh Province.
He was sent to centralized quarantine at a military camp in northern Bac Ninh Province. He had been tested negative twice for the new coronavirus during quarantine, but the third test arriving on Friday said he is positive.
The man is now treated at the Bac Ninh General Hospital.
Previously, 16 other passengers on the same flight were diagnosed with the disease.
With him on the list, Vietnam has now registered 1,213 Covid-19 patients and 1,070 of them have recovered, 35 died and three are not either counted as recoveries or Covid-19 deaths because they died after having been confirmed Covid-19 free.
Around the world, more than 1.24 million people have died of Covid-19.