A doctor wears protective gears before going into the quarantine room at a hospital in Hanoi, February 2020. Photo by VnExpress/Tat Dinh.

The man hails from the northern province of Thai Binh, around 100 kilometers from Hanoi. On February 17, he flew to Gimhae International Airport in Busan and traveled to Daegu, South Korea's Covid-19 epicenter. Accompanying him was his 24-year-old sister.

The duo and their two Vietnamese friends went to a supermarket in Daegu two times on February 18-19. Their friends returned to Vietnam on February 26 and were quarantined at Son Tay Military School in Hanoi.

The latest patient landed at Van Don Airport in the northern province of Quang Ninh on March 4 on a flight from Busan. Currently, all flights from South Korea have been diverted away from Hanoi, Saigon and Da Nang airports.

After entering Vietnam, he was quarantined and had his samples tested. The results showed him positive for Covid-19.

South Korea has so far reported over 7,000 Covid-19 infections, second only to mainland China, where the disease was first detected last December.

Vietnam confirmed its 17th infection case on Friday, after spending 22 straight days without any new infection. The patient was a 26-year old woman in Hanoi returning from Europe. She has been quarantined and is undergoing treatment at Campus No.2 of the Hanoi Central Hospital for Tropical Diseases.

All 16 persons confirmed with Covid-19 infections in Vietnam earlier have been discharged from the hospital.

The Covid-19 epidemic has spread to 100 countries and territories around the world with global death toll climbing to 3,500.

Starting Saturday, everyone coming to Vietnam have to fill health declarations.