The patients in Vinh Phuc Province contracted the virus from a group of Chinese experts over the weekend. The virus has been identified as the B.1.167 variant, a “double mutant” strain.
This marks the second time that the B.1.167 strain has been found in Vietnam but the first among community transmissions.
Patients at the current community transmission hotspot in Ha Nam, meanwhile, have been infected with the B.1.1.7 variant from the U.K.
Vietnam first recorded the Indian strain B.1.167 eight days ago in a group of Indian experts. They had been quarantined upon arrival at the Nhu Nguyet 2 hotel in the northern province of Yen Bai and transmitted the virus to a male receptionist working at the hotel. Such cases are not considered community transmissions.
The three patients in Vinh Phuc with the Indian virus strain are among six female staff of a bar who contracted the virus after coming into close contact with five Chinese male experts.
The experts had arrived in Vietnam early April and had also been quarantined at the Nhu Nguyet 2 hotel from April 9-23, during which time they tested negative thrice.
After completing their quarantine, the men began working at the Trung Bac A Company in the province and continued to have their health monitored for 14 days at another hotel by local medical staff.
However, the experts left their hotel and visited many localities in northern Vietnam from April 23 to 25. On April 28, they returned to China through the Huu Nghi border gate in Lang Son Province. Four of them have since been confirmed positive for the virus by Chinese authorities.
The group has so far led to 15 infections in Vietnam – 14 in Vinh Phuc and one in Hanoi.
The B.1.617 strain 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.
The World Health Organization (WHO) said the predominant lineage of B.1.617 was first identified in India last December, although an earlier version was spotted in October 2020.
The WHO has described it as a “variant of interest”, suggesting it may have mutations that would make the virus more transmissible, cause more severe disease or evade vaccine immunity. Other strains with known risks, such as those first detected in the United Kingdom, Brazil and South Africa, have been categorized as “variants of concern,” a higher threat level, Reuters reported.
The Indian variant has been found in at least 17 countries so far.
Until April 29, Vietnam had gone over a month without local transmissions. Since then, 36 Covid-19 cases have been confirmed, 35 of them related to people who had completed the mandatory quarantine, including the group of Chinese experts in Vinh Phuc and a man in Ha Nam. The remaining patient is a man in the central city of Da Nang whose transmission source is yet to be identified.