Additional resources to ensure widespread community testing in targeted locations in east London – including Shoreditch and Dalston – were put in place after the South African variant was also found.
The infections have occurred at three workplaces in the region, the Hackney Council said.
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Sky News watched in Shoreditch on Saturday morning as people started to flock to the center there.
Sky’s Jemima Walker said: “Most people say they’re not worried, they woke up this morning, saw the text message and came to the testing center. “
Surge tests to combat the Indian variant are also underway in several other parts of the country, including areas of Sefton, Merseyside, Bolton, Greater Manchester and Blackburn, Lancashire.
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Data from Public Health England shows an increase in cases of the worrying Indian variant from 520 to 1,313 in the UK, but those numbers are said to be at least a week behind.
It is believed that around 400 of them were in London.
A statement from the London Borough of Hackney said: “The council is now calling on all who work or live in these affected areas to take a test to help stop the spread of these variants in the community.
“These areas are around Old Street and Great Eastern Street in Shoreditch; and parts of downtown Dalston, around Dalston Lane and Kingsland High Street. “
Boris Johnson on Friday warned that the variant could cause a “serious disruption” to plans to ease the lockdown and could delay the scheduled end of all legal restrictions on June 21.
The Scientific Advisory Group for Emergencies (SAGE) determined that there was a “realistic possibility” the strain was 50% more transmissible than the one that emerged in Kent.
If the improved transmissibility of the variant is confirmed, experts said moving to the third stage could “lead to a substantial resurgence of hospitalizations” which is “similar to or greater than previous peaks”.
To limit the spread of the variant, people over the age of 50 and those who are clinically vulnerable have been urged to come and take their second dose of a COVID vaccine earlier than scheduled.
One of the biggest experts on variants, Professor Sharon Peacock, director of COG-UK, said on Saturday morning: “There are hot spots in London and the North West, but the variant is known to be present in many places across the country.
“An important question is how far B.1.617.2 has spread in England. Sequence data takes a week or more to become available, but there are other ways to track variations.
“All of this indicates that B.1.617.2 outperforms the other variants. Control measures through public health actions (tests, contact tracing, isolation) are very important because they slow down the spread of even highly transmissible variants and save us time.
“We do not yet know enough about B.1.617.2 and the severity of the disease. There is no evidence that B.1.617.2 causes more severe disease, but more data is needed to begin to understand this. ”