The UK is bracing for a surge in infections from another coronavirus strain first detected in the subcontinent.
The Delta variant, originally found in India, is currently the dominant strain in Britain and is feared by scientists to be up to 60 per cent more transmissible than the UK/Alpha variant it supplanted.
The emergence of the closely related Nepal variant, labelled K417N, is thus a worrisome development.
This is what is known.
What is the Nepal K417N variant – and is it a variant at all?
Officially, Nepal variant is a misnomer.
It is yet to be recognised as either a “variant under investigation” or a “variant of concern”, and the World Health Organisation said on Thursday there is a difference between variants and mutations.
More accurately, the Nepal variant is the Nepal mutation: the Delta variant with the K417N spike mutation tacked on.
This mutation is similar to the Beta variant, which was first detected in South Africa in October last year.
There is no scientifically agreed definition for the point when a mutation becomes a "variant of concern", but the decision will be predicated upon how it spreads, how sick it makes people, and if it evades vaccines.
Whether mutation or variant, using Nepal in its designation rather goes against the spirit of the WHO's recent recategorisation of Covid variants.
After months of deliberation, the coronavirus nomenclature was changed to letters from the Greek alphabet to avoid stigmatising the countries where variants are first detected.
How prevalent is the Nepal mutation in the UK?
More than 20 cases of the Nepal mutation had been detected in the UK as of Monday June 3, officials said.
This represents a mere sliver of the overall caseload but, as the Delta variant is currently showing, from small beginnings new infections can take off with alarming speed.
How transmissible is the Nepal mutation?
With insufficient data available to date, its level of transmissibility is unknown but is likely to be high, given it is a mutation of the extremely transmissible Delta variant.
What is the UK doing about the Nepal mutation?
Public Health England said on Monday it was urgently investigating the Nepal mutation.
The UK government on Monday removed Portugal from its green list for travel, a decision in part ascribed to rising cases of the Nepal mutation in the Iberian country.
Will vaccines work on the Nepal mutation?
This is as yet unknown but the UK government believes it is a possibility, as Transport Minister Grant Shapps outlined when announcing changes to the UK’s travel lists on Monday.
"There's a sort of Nepal mutation of the so-called Indian variant which has been detected and we just don't know the potential for that to be a vaccine-defeating mutation," he said.
The signs look inauspicious, however, because the K417N mutation is believed to partially account for the Beta variant's ability to evade vaccines and antibodies gained from previous infections.
Will the Nepal mutation affect the June 21 ending of Covid restrictions in the UK?
It is likely that the Delta variant will determine whether Covid restrictions are lifted in the UK as planned on June 21. A mutation of this variant that potentially makes it more likely to evade vaccines does not bode well for the removal of all restrictions.
Leading UK epidemiologist Prof Neil Ferguson on Friday told the BBC that June 21 was a “difficult judgement call” for Prime Minister Boris Johnson.
“The data is pointing this week in a more negative direction than last week,” he said.