Almost a quarter of all coronavirus transmission in London last month was driven by ‘variants of concern’, data suggests.
Scientists tracking the spread of mutant Covid strains estimated about 25 per cent of cases in the capital were variants other than the dominant Kent version by mid-April.
At that time, the Indian variant was being imported into the UK via people returning from Covid-stricken India in a dash to beat the UK’s travel ban from Delhi.
The researchers said the bulk of the new variant cases were likely the Indian B.1.617.2 strain, which has since spread rapidly across Britain and gained a foothold in parts of London and the North West.
But they said surge testing for the South African variant in South London will have also made up a significant proportion of the cases. A smaller number of people tested positive for the Brazilian P.1 variant and other strains circulating less widely.
Imperial College London researchers drew on data from the UK’s variant-tracking laboratories, national infection surveys and the Government’s centralised testing programme.
They said it was likely that concerning variants now make up more than 25 per cent of Covid cases in the UK because of how rapidly the Indian strain is spreading.
There have already been almost 3,500 cases of the mutant strain, according to Public Health England’s most recent count on May 19, which is five times more than at the start of this month.
The Scientific Advisory Group for Emergencies (SAGE) believe the Indian strain is far more transmissible than the already highly virulent Kent variant but the group has ‘increasing confidence’ vaccines work well against it.
But MailOnline’s analysis of official numbers show just three of the 23 places in England where the Indian variant has become dominant are seeing clear rises in infection rates.
Dr Simon Clarke, a microbiologist at Reading University, told this website that the mutant strain would not be the ‘disaster’ initially feared because it appeared to be confined to pockets of the country.
For example, there were just 2,874 Covid infections across Britain yesterday – which was in line with the case rate for the past month – and 10 per cent of all infections were in Bolton, where the Indian variant is spreading fastest.
But the number of patients in hospital with the virus in the Greater Manchester town is creeping up and Bolton NHS Foundation Trust has opened an extra Covid ward. There are now 30 patients being treated for the disease after five more were admitted yesterday.
Health Secretary Matt Hancock said the ‘majority’ of the patients were unvaccinated and among the few who had been given a jab, they had not been for their second appointment.
Blackburn has also seen a spike in cases following surge testing in the area, as has Bedford, where a secondary school has resorted back to remote learning due to the outbreak.
It came after PHE revealed last night that it had detected another mutant Covid variant in Yorkshire and the Humber, which it has assigned as a ‘Variant Under Investigation’.
The strain — temporarily named AV.1 — has been spotted 49 times so far and there is currently no evidence that it causes more severe disease or renders vaccines less effective. Its effect on transmission is not yet understood.
Some newspapers carried reports of the new strain being a ‘triple mutant’ variant because it appears to have three key mutations. But Cambridge University immunologist Brian Ferguson described that description as ‘meaningless’, pointing out that the Kent variant has 23 mutations which separate it from the original strain that emerged in China.
The variants currently in circulation in the UK: The second Indian variant (B.1.617.2) is causing the most concern as it appears far more transmissible than the dominant Kent strain. The South African variant is believed to be the least responsive to vaccines, reducing their ability to block infections by about 30 per cent
Scientists tracking the spread of mutant Covid strains estimated about 25 per cent of cases in the capital were variants other than the dominant Kent version by mid-April. The three most common variants are the Indian variant (in purple), the South African variant (green) and a separate, less virulent version of the Indian variant is in blue
Imperial College London researchers drew on data from the UK’s variant-tracking laboratories, national infection surveys and the Government’s centralised testing programme. Domestic strain B.1.525 and B.1.1.318, as well as the Brazilian P.1 variant, are circulating in smaller numbers
Positive test figures from the Wellcome Sanger Institute – which cover only lab-analysed cases in the two weeks between April 25 and May 8 – reveal the mutant Indian strain made up 50 per cent or more of all samples in 23 parts of the country by last week. Bolton and Blackburn in the North West remain the worst-hit areas with almost 600 cases between them and the variant making up 81 per cent of infections
While the Indian variant is spreading rapidly in pockets of the country, 60 per cent of local authorities in England have yet to record a case (shown in grey). But it is likely the variant has spread even further than the map suggests because the data only goes up to May 8. Experts have said they expect it to overtake the Kent strain and become dominant in the coming weeks and months
In a promising sign that the vaccines are giving high protection, Covid infection rates are not rising in over-60s in any of the areas outside of Bolton where surge testing for the Indian strain is being carried out.
Swabbing drives were launched in Blackburn, Bedford, Burnley, Hounslow, Kirklees, Leicester, North Tyneside, Glasgow and Moray in an attempt to stomp out the mutation.
Latest PHE figures published last night said the B.1.617.2 variant had been detected 3,424 times by May 19, up from 1,313 a week ago.
The bulk of the cases have been in the North West of England — mostly in Bolton and Blackburn — and in London but PHE said clusters were cropping up across the country.
In England, 3,245 cases have now been confirmed, with another 136 in Scotland, 28 in Wales and 15 in Northern Ireland.
Boris Johnson said earlier in the week he was confident the lockdown-easing roadmap could go ahead because he had seen data which suggested the Indian strain is unlikely to be 50 per cent more transmissible than the Kent variant, a figure quoted by SAGE last week.
There is still no consensus about how virulent the strain truly is or what impact it will have on the national epidemic, with firmer evidence not expected for at least another week.
SAGE adviser Professor Andrew Hayward warned yesterday that he believed the UK was on the cusp of a third wave, saying it had him ‘very concerned’.
Others, like Reading’s Dr Clarke, believe the vaccines are so effective against the strain that it should not overwhelm the NHS.
But Professor Hayward told the BBC yesterday: ‘It has spread fairly effectively first of all within households and now more broadly within communities, so I don’t really see why it wouldn’t continue to spread in other parts of the country.
‘There’s still people who aren’t vaccinated in high-risk groups, the vaccine isn’t 100 per cent effective, and also even in the younger groups if you get many, many thousands or hundreds of thousands of cases, then you will expect a lot of hospitalisations and deaths to result from that.
‘So that’s the threat. And it’s really over the next week or two we will see how much these outbreaks that at the moment are relatively localised, how much they become generalised across the population. And if that happens, that’s when we’re going to be much more worried.’
Despite the warnings, ministers are believed to have gained confidence from the fact that, despite cases soaring in Bolton, they haven’t rocketed quite the same in other hotspots.
Top SAGE adviser Professor Neil Ferguson said earlier this week that the virus was spreading fast in the Greater Manchester town due to its large South Asian community and multigenerational households, as opposed to the virus being extremely virulent.
He admitted the strain was likely to be more virulent than the Kent one, but that it would be much more ‘manageable’ if it turned out to be 20 or 30 per cent more transmissible, as opposed to 50 per cent.
Ten per cent of all the infections in the UK yesterday were in Bolton, where the case rate has risen sevenfold in a month to more than 300 per 100,000 population – on par with the rate during the worst of the second wave.
Blackburn and Bedford are the other two Indian variant hotspots were the overall Covid rate is also above 100 per 100,000. In the other hotspots cases are remaining flat in others and even falling in two — Sefton and South Northamptonshire.
It came as the Office for National Statistics found England’s Covid outbreak may be on the rise amid surging cases of the Indian variant.
ONS’ swabbing survey found almost 50,000 people were infected with the virus on any day last week, up 20 per cent on the previous seven-day spell.
The national body, whose estimates are watched closely by ministers, warned that it was starting to see a ‘potential increase’ despite infections remaining low overall at just one in 1,110.
Its head of analytics for the Covid infection survey Sarah Crofts said: ‘Although we have seen an early indication of a potential increase in England, rates remain low and it is too soon to say if this is the start of a trend.’
But the figures came after data yesterday suggested the opposite, allaying fears the Indian variant was spiralling out of control.
Public Health England found Covid cases had dropped in every region except the North West and in every age group except 5 to 9-year-olds.
Separate analysis from King’s College London found 2,270 Britons were catching symptomatic Covid last week, barely a change from the previous seven-day spell.
Covid cases did not fall in any of England’s nine regions last week, results from the ONS’ infection survey suggest.
They may have risen slightly in the North East, Yorkshire and the Humber, West Midlands, East of England and the South East, results showed, but still remained at very low levels.
London and the North West — which are hotspots for the Indian variant — were both estimated to have seen their Covid cases remain flat last week.
Across age groups Covid cases were only predicted to have risen among 35 to 49-year-olds and over-70s, but remained at very low levels with a positivity rate of 0.15 and 0.11 per cent respectively.
They fell among 12 to 24-year-olds (down to 0.20 per cent), and 50 to 69-year-olds (down to 0.03 per cent) who have all been offered at least one dose of the Covid vaccine.
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