Eight boroughs have now gone above the key threshold of 100 new cases a week per 100,000 population.
With the exception of Richmond of Thames, nine out of 10 boroughs with the highest coronavirus rates are north of the Thames.
Richmond has a rate of 133.3 (264 cases), Hackney and the City of London area 124.8 (363 cases with the vast majority of them in Hackney) , Redbridge 124.5 (380 cases), Harrow 114.7 (288 cases), Haringey 109.4 (294), Barnet 106.3 (421), and Hammersmith & Fulham 101 (187).
The Evening Standard spoke to a PHE London official who stressed that while there is not one explanation for why some boroughs are more impacted than others, there is a notable difference in how the virus is spreading in the north east of London as opposed to the south.
They explained that transmission tends to be linked with households mixing and a larger household mixing with another household will likely contribute more to the spread of coronavirus.
This suggests the density of the population in each London borough could impact the rate at which the virus is spreading.
Two weeks before London moved into the “high risk” category, Tower Hamlets Mayor John Biggs advised residents to avoid mixing with other households “unless absolutely necessary”.
Mr Biggs, told residents it was a “matter of life and death” as the borough’s deputy Mayor Rachel Blake stressed that households mixing was a key factor contributing to the spread of the virus.
Speaking at the time of Mr Biggs’ announcement, Ms Blake told the Standard: “We’ve got the fourth highest infection rate in London. Our evidence shows that households visits is a high area of transmission and that is why we are asking people to avoid visiting other households.”
The PHE official added another contributing factor could be related to the two age categories of 20 to 29-year-olds and 17 to 19-year-olds mixing together.
The Prime Minister had expressed concerns in September that young people were contributing to the spread of the virus by failing to social distance and by holding large gatherings.
Mr Johnson’s officials spokesman said “young people in particular” had to ensure there was “no complacency” when it came to following the guidance on how to prevent the virus from spreading.
However while coronavirus rates are currently higher in boroughs north of the Thames, the PHE official warned that boroughs in the south of the capital are increasingly displaying higher rates of Covid-19 and could be catching up to the northern boroughs.
Professor Kevin Fenton, London Regional Director for PHE, told the Standard: “All London boroughs have rising rates of Covid-19 and these vary across the city with boroughs north of the river being most impacted so far, but with south London boroughs now catching up.
“Household mixing has been a key factor driving transmission across the city, particularly in areas where households have more people living under one roof. Another driver of infection rates in London has been transmission amongst young adults, especially as they socialise with each other in neighbourhoods, homes and social venues across the city.
“It is therefore incredibly important that we stick to the new restrictions to help slow the spread of disease, both within individual boroughs and between them.”
It comes as tighter Tier 2 restrictions come into force in London from midnight today. Under the stricter measures, Londoners are banned from mixing between households indoors, including in pubs and restaurants.
Unveiling the new clampdown, Matt Hancock said infection rates in London are on a “steep upward path” and confirmed cases are doubling every 10 days.
The Health Secretary told MPs: “The seven-day average case rate stands today at 97 rising sharply. We know from the first peak, the infection can spread fast and put huge pressures on the NHS so we must act now to prevent the need for tougher measures later on.
“So working closely with the mayor, with cross-party council leadership, with local public health officials and the national team, we’ve together agreed that London needs to move to local Covid alert level high.”