All four were among 345 Vietnamese citizens repatriated from Russia on a Vietnam Airlines flight that landed May 13 at the Van Don airport in the northern province of Quang Ninh. A total of 34 passengers on the flight, including two attendants, have been confirmed infected so far. Eight other patients on the flight had been declared healthy earlier.

The latest four recoveries, three men and a woman, were treated at the Thai Binh General Hospital. They tested negative at least twice.

Vietnam has confirmed 328 Covid-19 cases so far, of whom 302 have recovered.