Vietnam's health authorities say a new coronavirus variant has been found in four people infected with a variant first discovered in India.
A mutation was found in part of the genetic material of spike proteins on the surface of the virus. These play a crucial role when the virus infects human cells.
Vietnam's authorities say the mutation resembles a notable one of the variant first found in Britain.
An official at the World Health Organization office in Vietnam told NHK that the transmissibility of the new variant is not yet known, but that the status of infected people should be closely watched.
Vietnam had successfully contained the spread of the virus, but variants have been found since the beginning of the year. The number of new cases has been rising since the end of April, topping 400 on some days.