Two women and three men, numbered 1070-1074 and aged 27-34, flew on the same flight from France to Ho Chi Minh City's Tan Son Nhat Airport Friday and were quarantined upon entry.
They tested positive for the novel coronavirus Saturday, and are being treated at the Binh Duong General Hospital in southern Binh Duong Province, which borders HCMC.
All five are residents of the northern province of Ha Nam.
Vietnam has recorded 1,074 Covid-19 cases so far, and has lost 35 people to the pandemic. Many of the 35 were elderly patients with underlying conditions like diabetes or kidney failure.
Out of the active cases, 19 have tested negative for the virus at least once. Over 16,000 are in quarantine at present.
No community transmission has been recorded nationally for 25 days now.