TWO NEW VARIANTS of SARS-CoV-2, the coronavirus that causes Covid-19, are spreading in Ireland.
One strain, known as B117, was confirmed Ireland on Christmas Day and has occurred in several countries since it was first identified in the UK last month.
Another strain, 501.V2, was detected in South Africa in October, is also causing concern after spreading to European countries including Britain and France. Three cases of this variant were confirmed in Ireland by health officials on Friday.
Evidence suggests that both strains are far more transmissible than other variants of SARS-CoV-2.
The emergence of both prompted an unprecedented decision by the government last month to suspend travel from the UK and South Africa for two weeks over Christmas.
That move appears to have come too late to stop B117 and 501.V2 arriving on Irish shores.
Health officials now estimate that a quarter of new cases of the illness in Ireland are due to the UK strain, which may be one factor in record case figures and hospitalisations set this week.
Even before this week’s alarming figures, the spread of B117 had caused consternation among politicians and health officials.
“It is already very clear that we are dealing with a strain of the disease that spreads much, much more quickly,” Micheál Martin told the nation as he announced a new national lockdown on 30 December.
“Indeed, it is spreading at a rate that has surpassed the most pessimistic models available to us.”
There were initial concerns that both variants could set back the global response to Covid-19 if they were immune to newly developed vaccines or if they were even more severe than other strains.
In the case of B117, neither of these worries appear to have played out: research by Pfizer/BioNTech suggests the variant does not impact on the companies’ vaccine, while public health institutes and scientists have said patient outcomes are no worse than with other strains.
But although this might bring some respite, there is still much we don’t know about the variant – including how responsible B117 actually is for the sharp rise in cases.
What we do know is that the more transmissible nature of the new strains is a huge problem in and of itself, and could cause Ireland’s Covid-19 response to spiral further out of control.
What’s more, further studies are required to detect the extent to which 501.V2 affects the efficacy of vaccines.
Natural variations
New strains of SARS-CoV-2 are nothing new. The virus has mutated many times since it first emerged in 2019, and variants in RNA viruses arise naturally as they replicate.
Around 4,000 mutations of SARS-CoV-2′s spike protein have been identified to date, the vast majority of which have had no effect on the virus or how it impacts people.
B117 and 501.V2 are different. They each have a specific mutation in their spike protein – the part of the virus that allows SARS-CoV-2 to gain access to our bodies – known as N501Y.
The nature of these mutations is not fully known yet, but recent research has suggested that both strains are far more transmissible than other strains of SARS-CoV-2.
A study by London’s Imperial College found that B117 raises the R number by between 0.4 and 0.7 – meaning those who catch it will pass it on to 40-70% more people than they would if they had previous variants.
The UK’s NERVTAG committee, an expert group which advises the government, also estimated that B117 is between 50 and 70% more transmissible.
Although it only came to prominence last month, the new variant was first identified on 21 September by scientists from a group known as Covid-19 Genomics UK (COG-UK).
Initially, COG-UK reported around 1,000 people who had contracted B117, chiefly based in the south-east of England, but reports soon emerged of patients who had contracted it in places as far away as the US, New Zealand and Thailand.
At a briefing on 15 December, Nick Loman, professor of microbial genomics and bioinformation at the University of Birmingham, explained that the new variant almost certainly originated domestically before spreading to other countries.
“There are no data to suggest it had been imported from abroad, so it is likely to have evolved in the UK,” he said.
Ten days later – after the government had announced travel restrictions from the UK and South Africa – the Chief Medical Officer Dr Tony Holohan confirmed that B117 had been detected in Ireland.
That was the only significant variant in Ireland until Friday, when three cases of the South African strain were confirmed by health officials.
501.V2 was first detected in Covid-19 in samples from October and reported by South Africa’s health department on 18 December.
Like B117, it is not currently considered more severe than other strains, but it is associated with higher rates of transmission. It also comes with additional problems.
Although the mutation to 501.V2′s spike protein is similar to that of B117, more studies are needed because it is not the only change the strain has undergone.
Another mutation – known as E484K – has been shown to reduce antibody recognition, which would help SARS-CoV-2 bypass the immune protection given to a person who has previously been infected or vaccinated against other strains.
Professor Shabir Madhi, who led trials for the Oxford-AstraZeneca vaccine in South Africa, told the BBC that the new variant could “theoretically” make vaccines less effective against Covid-19.
He added that although it was “unlikely” that 501.V2 would make newly developed vaccines completely useless, the new strain could “weaken the impact” of them.
Meanwhile, Sir John Bell, Regius professor of medicine at Oxford University, also told BBC this week that there was a “big question mark” over whether the vaccine developed by the university and AstraZeneca would be as effective against 501.V2.
He said the team that developed the vaccine were investigating the issue as a matter of urgency.
‘Not easy to control’
Despite being no more severe than other strains and its apparent lack of impact on newly developed Covid-19 vaccines, the spread of both variants present serious problems to how countries manage their response to the virus.
Professor Mark Woolhouse, an infectious diseases expert at the University of Edinburgh, warned this week that B117 in particular will not be as easy to control through lockdowns.
He also said that simply stopping the situation from getting any worse than it currently is in the UK, where record cases of Covid-19 have also been reported this week, would be “a good outcome”.
“The new variant is not going to be as easy to control as the old variant, the one that was controlled by the lockdown in March, so we’ll have to wait and see,” he told the BBC.
Adam Kucharski, a professor at the London School of Hygiene & Tropical Medicine, previously outlined how the increased transmissibility of new strains like B117 and 501.V2 are potentially much worse than a variant that would cause more severe cases of Covid-19.
He set out a plausible scenario for many European cities, in which the virus has a reproduction rate of 1.1, an infection fatality risk of 0.8%, an infection-generation time of six days, and 10,000 active infections.
Mathematical modelling under such circumstances, according to Kucharski, would result in around 129 deaths in a month.
If there was a mutation in the virus that caused a 50% increase in the fatality rate – as might be expected with a more severe strain of the virus – that would lead to 193 deaths under the same circumstances.
By contrast, a 50% increase in the spread of Covid-19 – which is among lower estimates for the transmissibility of B117 – would lead to an extra 978 deaths in a month under these circumstances, because of the huge numbers of additional people whom the virus would infect.
Such an outcome would depend on which sections of the population contract the virus (for example, increased severity might lead to higher fatalities among younger people, who are less prone to dying from previous strains, than increased transmissibility which is the case with this variant).
But this modelling is not good news for countries grappling with the spread of the new variants on top of increasing case numbers as a result of other factors.
Along with more deaths, it would bring increases in hospitalisations due to Covid-19 – which passed 1,000 in Ireland for the first time this week – and the number of patients in intensive care.
With the country’s intensive care capacity approaching its limit and modelling already far past even the worst-case scenarios envisaged in December, Ireland’s health service may struggle to cope with an even greater surge in cases.
‘Making some contribution’
Given the spread of Covid-19 in Ireland in recent weeks, many will speculate – as the Taoiseach did in both of his speeches announcing Level 5 restrictions in December – that B117 is largely responsible for the rapid increase in Covid-19 cases.
Daily figures are now multiples of what they were during the first wave of the pandemic, and the R number is estimated to be as high as 3 – 66% higher than at any stage last spring.
Yet analyses carried out by public health officials suggest that the new strain may be less of a factor than is being claimed.
Professor Philip Nolan chair of NPHET’s epidemiological modelling group speculated that B117 “may be making some contribution”, but figures suggest the variant is not currently behind the huge increase in cases.
Last weekend, director of the National Virus Reference Laboratory Dr Cillian De Gascun highlighted how the variant was found in fewer than 10% of samples of positive cases, tweeting that it was “not responsible” for the recent surge in case numbers.
The Chief Medical Officer reported earlier this week that the figure had risen to just 25% of new cases after further analyses, suggesting that recent increases are also being driven by something else.
Professor Derek Doherty, an immunologist at Trinity College Dublin, told RTÉ’s Prime Time this week that a sharp rise in case numbers is instead likely down to the relaxation of Covid-19 restrictions over Christmas.
“It’s unlikely that B117 is responsible for the recent surge of cases of Covid in Ireland,” he said.
Deputy Chief Medical Officer Dr Ronan Glynn also emphasised at a briefing this week that there was still a lack of data about the new strain’s impact in Ireland.
“All we know with a relatively high degree of confidence at the moment is that the variant is more transmissible than what we were dealing with heretofore,” he told reporters.
This may be a source of optimism: if B117 is not a major factor in the recent rise in case numbers, it has less of a foothold in Ireland and can be controlled more easily.
Health officials remain clear that regardless of the new strain, the measures which Ireland has become used to over the past nine months are required more than ever: regular hand-washing; wearing face masks; reducing contacts; and socially distancing.
If new case numbers beginning to flat-line next week, the new restrictions may begin to have an effect.
NPHET has said its aim in the coming weeks will be to slow the spread of B117 while current restrictions are in place.
Though the new strain may not currently be a major factor, preventing it and 501.V2 from becoming more dominant in Ireland will be key in the months ahead. Doing so may ultimately save thousands of lives.
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