Hundreds of Covid tests in Hackney have been sequenced since the council ramped up testing in areas with variants of concern.
It reports "no particular increase" in positive tests so far.
Hackney council has already distributed over 5,500 tests, out of 7,000 households, to monitor the levels of new Indian and South African Covid variants of concern.
It has had about 600 returns after appealing to the public living and working in affected areas.
These include parts of Shoreditch, around Old Street and Great Eastern Street; and parts of Dalston town centre, around Dalston Lane and Kingsland High Street.
The genomic sequencing used to identify variants takes longer than the initial positive test results for coronavirus, which is usually sequenced within 24 hours.
It can take a week or longer for a positive result for a variant of concern.
Dr Sandra Husbands, director of public health for the City and Hackney, explained that by the time the council has received this information self-isolation measures and robust contact tracing would have already taken place.
She added: "But this information is still useful to us, as it helps us monitor the effect of the variant on the community, such as its likelihood of spreading or if it makes people more ill than before."
General local Covid data shows Covid deaths are down to zero in Hackney, in the week ending May 7, and all-cause mortality has been well below the five-year average for weeks.
Hackney also had the second lowest incidence of Covid in London that week, with 10 cases for every 100,000 people.
Dr Husbands says the best way for residents to protect themselves against all variants is to get vaccinated and tested regularly, while continuing to practice "hands, face, space" when leaving home.
The doctor added: “The most important thing we are looking for when testing is if the person has the virus or not, not which variant it is.
"So within 24-48 hours we have the positive test result and are able to let the person know they need to self isolate for 10 days to stop the virus spreading around the community.
"This is our main objective with testing."
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