Indian and other ‘variants of concern’ were behind a quarter of Covid cases in London by mid-April, data shows as experts say mutant strain spiralling in Bolton is not the ‘disaster’ first feared with cases only rising in THREE of 23 hotspots

  • Scientists tracking spread of mutant variants said about 25% of cases in capital last month weren’t Kent strain
  • They said bulk of variant cases were likely Indian B.1.617.2 strain, which has since spread rapidly across Britain
  • Imperial College London used data from variant-tracking labs, infection surveys and central testing scheme

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, accounting for 5 per cent of the UK’s total infections, 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. 

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