The seven samples were taken from coronavirus patients in the northern provinces of Vinh Phuc, Bac Ninh, Lang Son and Nam Dinh, said the National Institute of Hygiene and Epidemiology. All samples were revealed to carry coronavirus variant B1.617.2, first found in India.

Previous genetic sequencing results also showed the presence of the variant among several coronavirus cases in Hanoi and the nearby Hung Yen and Thai Binh provinces.

The B.1.617 variant contains two key mutations called E484Q and L452R, which have been found separately in other variants but not together in a single strain. These mutations have been found to make the virus more transmissible and to be less susceptible to neutralizing antibodies, experts said.

Minister of Health Nguyen Thanh Long said the Indian variant could be even more transmissible than another variant found in the U.K. called B.1.1.7, which is believed to be more transmissible than ordinary strains but not more deadly.

Covid-19 testing therefore is both crucial and urgent to detect potential cases in the community, Long said.

The Indian coronavirus variant was first detected on April 30 among a group of Indian experts and a Vietnamese man working at a hotel where the Indians were quarantined, the Ministry of Health said.

The variant's particularly high transmissibility was credited to recent coronavirus outbreaks around the globe, including the latest Covid-19 wave in India that has pushed its medical system on the brink of collapse.

Hanoi's National Hospital for Tropical Diseases was locked down earlier this month after it was revealed to be a major coronavirus hotspot, with hundreds of associated cases detected in several cities and provinces beyond the capital.

As of Tuesday, 80 coronavirus cases have been associated to the hospital.

Vietnam is currently facing its toughest Covid-19 wave yet, which has seen 502 community cases in 26 cities and provinces since late last month. On Monday, 125 community cases were recorded in a single day, the highest daily infection tally observed ever since the disease appeared in Vietnam early last year.