Vietnam has suspended international flights from today into its capital, Hanoi, and commercial hub, Ho Chi Minh City, as it tries to control a suspected new hybrid coronavirus variant that it fears is fanning the Southeast Asian nation's worst outbreak of the pandemic.
China has also tightened its border security as its neighbour, once considered a pandemic success story, now plans to test all 13 million residents of Ho Chi Minh City and tighten social distancing measures.
Vietnam's plight follows a now familiar pattern of Covid-19 surges across Asia - most alarmingly in countries such as Singapore, Laos, Thailand and Taiwan that were praised for beating the virus last year, only to be caught out by a global vaccine shortage as new variants ricochet back from coronavirus hotspots.
On Saturday, Vietnamese authorities revealed they had discovered a "very dangerous" new coronavirus variant that combined mutations first found in India and the UK, and which spreads quickly by air.
Health Minister Nguyen Thanh Long said Vietnam would soon publish genome data of the newly identified variant, which he said was more transmissible than the previously known types, reported Reuters.
He said laboratory cultures showed the virus replicated itself very quickly, possibly explaining why so many new cases had appeared in different parts of the country in a short time.
Vietnam has so far had just over 7100 Covid-19 cases and 47 deaths, but more than 4000 of these cases have emerged in an outbreak that came to light on April 27, and which has been detected in 34 cities and provinces.
The World Health Organisation (WHO), which has identified four variants of concern – emerging from the UK, India, South Africa and Brazil - is investigating Vietnam's findings.
Maria Van Kerkhove, WHO technical lead for Covid-19, said the variant detected in Vietnam was understood to be the B.1.617.2 variant, more commonly known as the Indian variant, possibly with an additional mutation, but that more information would be provided when it was received.
Today, @WHO announces new, easy-to-say labels for #SARSCoV2 Variants of Concern (VOCs) & Interest (VOIs)
They will not replace existing scientific names, but are aimed to help in public discussion of VOI/VOC
On Monday, the WHO, International Monetary Fund (IMF), World Bank Group and World Trade Organisation (WTO) warned of a "two-track pandemic" where inequitable vaccine distribution was leaving millions vulnerable to the virus and creating deadly variants to boomerang around the world.
Like many other countries in the Asia-Pacific region, Vietnam has struggled to obtain vaccines, and to date has only reached 1 per cent of its 96 million-strong population with a first dose. This week, the Government asked Samsung Electronics Co, and other foreign companies to help source vaccines for their workers.
Abhishek Rimal, the regional coordinator for public health in Asia Pacific, International Federation of Red Cross and Red Crescent Societies, said although the full genomic sequence of the potential hybrid was still unclear, initial reports were worrying.
"What we understand from the field and some of the epidemiologists from the country is that they do suspect it will have even higher transmissibility than the original strain or any of the variants," he told the Telegraph.
"If confirmed, we could see a steep rise of Covid-19 in Vietnam and even beyond around Southeast Asia."
The variant could be spread through illegal border crossings or, like other variants, through quarantine or tracing loopholes in arrival countries as infected people travel. Vietnam is not on the UK's red list, which would require arriving passengers to undergo 10 days of quarantine in a hotel.
The vaccine shortage has left Vietnam reliant on intensifying public health measures which have been effective in crushing outbreaks since the pandemic began, but are increasingly harder to maintain.
The April surge reportedly traces back to returning overseas travellers and Chinese migrants crossing the borders illegally. It later swept through hospitals and industrial zones.
Local media have also carried reports of breaches at quarantine hotels spreading to nightclubs. A major cluster also sprang up in a religious mission in the Go Vap district of Ho Chi Minh City, prompting a raft of new measures.
The city has now closed shops, restaurants and suspended religious activities, while restricting gatherings to 10 people and enforcing two-metre social distancing rules.
People over 60 have been encouraged to stay home as the authorities begin about 100,000 tests a day.
Pharmacist Thu Nguyen said people had voluntarily started working from home even though only Go Vap was fully locked down.
"People are concerned, but they're generally more concerned about how the cluster is spreading nationally," she said, adding that there were fears the new variant may affect young and healthy people more than previous strains.
Nick Hum, an art director in the design industry, said locals and expatriates were a "bit scared" about reports of a more dangerous strain and some foreigners were leaving.
But he added that "there is also a sense, a strong trust that the Government will control the situation," as it had before. "The entire population is masked up and observing 'stay at home' orders," he said .
Rimal said that strict public health measures were going to be vital for Vietnam and other Southeast Asian countries until richer countries shared more of their vaccines.
"No one is safe until everyone is. If the people are not vaccinated in another part of the world, there will be a mutation, there will be a new variant, and the vaccines will be of minimum use," he said.
"We will go round in circles, and so it's absolutely important to realise this global solidarity and get more people vaccinated."