With coronavirus inoculation programmes launching the world over, hopes began to rise that the end of the pandemic could be in sight.
But the emergence of new, more infectious variants and a surge in cases made it clear that the global fight against Covid-19 is far from won.
One strain, first identified in the UK (known as VUI 202012/01) is been blamed for a heavy increase in cases in London and other parts of England. A similar but separate variant found in South Africa (known as 501Y.V2) is also thought to be causing infections there to dramatically rise.
So what are these new strains and what problems could they cause? The National explains.
What is different about the new strains?
The strain first detected in the UK was traced to samples collected in London and south-east England in September. It has 23 mutations in its genetic material, 17 of which affect the virus’s proteins, and eight of these affect the spike protein – which the virus uses to attach to human cells.
Such mutations arise randomly as the virus replicates its RNA genetic material, but ones that confer a benefit to the virus are likely to become more common.
One spike protein mutation, N501Y, may make it easier for the virus to bind to and infect human cells, where it reproduces.
Other mutations in the UK variant are linked to increased infectiousness.
The South African variant has the same N501Y mutation, but researchers concluded that it arose independently.
Why are the new strains a problem?
Because of the mutations they contain, especially those that enable them to infect cells more easily, the new variants spread faster between people.
The UK form spreads as much as 70 per cent more easily, but is not thought to make people more ill.
But there are concerns that the South African variant might cause more illness among younger people, because the country has recorded an increase in severe cases among younger, otherwise healthy people.
How widely are they likely to spread?
The UK variant is becoming increasingly common there and has also been found in Australia, Belgium, Denmark, France, Gibraltar, Hong Kong, Italy and the Netherlands, while the South African form has been detected in the UK. It may be more widely distributed, because only a small proportion of coronavirus samples have their genetic material sequenced.
Prof Paul Hunter, an infectious diseases specialist at the University of East Anglia in the UK, said they would probably become the dominant strains globally, mirroring what happened with a variant, D614G, that appeared early this year and is characterised by a particular spike protein mutation.
“[D614G spread] quite rapidly and came to dominate the variants globally. Almost certainly one or the other of these new variants will do that,” he said.
What will the variants mean for infection rates?
Prof Hunter described the new variants as “really bad news” for controlling the pandemic. Work he and his colleagues have done, but not published yet, suggests that during England’s national lockdown in November, the reproduction number (R) – the number of people an infected individual spreads the virus to – fell to about 0.7 at best. But the new UK variant adds at least 0.4 to R. So even measures such as the closure of non-essential shops, restaurants, cinemas and gyms, may not keep R below 1 and stop infections from increasing.
“We know that because it [the new UK variant] was growing during the lockdown,” Prof Hunter said. “Every other variant was in retreat except for this one. It does mean it’s going to be really difficult.”
Where did the new forms arise?
Although one strain is linked to the UK and the other to South Africa, researchers cannot say for certain that these countries are where they evolved.
The UK has done as much genetic sequencing of coronavirus samples as the rest of the world put together, so is more likely than other nations to detect new variants wherever they arose.
Similarly, it is possible the strain first detected in South Africa evolved outside the country.
Will vaccines still work?
The coronavirus vaccines cause people to produce antibodies that recognise numerous sites on the spike protein, so a single change is unlikely to have much effect on their effectiveness. However, researchers are carrying out laboratory analysis to confirm this.
Scientists may have to produce new vaccines in future in response to further evolution of the coronavirus, such as for seasonal influenza. But, for the moment, this is not thought to be necessary.
The vaccines based on messenger RNA, a type of genetic material, such as the Pfizer-BioNTech vaccine used in Dubai, and the Moderna vaccine, could be tweaked particularly easily.