The latest data from the ONS infection survey confirms that coronavirus prevalence has been falling in London since the end of last month. This is occurring at the same time as last year, despite no lockdown being imposed this time and the emergence of the Omicron variant.
The data also shows that in the last week of 2021, an estimated 6% of the population of England or one in 15 people would test positive for COVID-19. This compares to a peak prevalence last winter of around 2%, so around three times higher.
The breakdown by age shows high prevalence in all age groups and particularly those under 50. Most age groups appeared to be peaking at the end of December, though in the over-50s infections were rising albeit from a lower level.
The ONS estimates back up the data from the ZOE Covid Symptom Study, which tracks self-reported symptomatic Covid via an app and shows reported infections falling sharply in London since the end of December.
ZOE also shows reported symptomatic infections falling across England and particularly in the East and South East of the country.
As noted above, this apparent peaking and falling is happening around the same week as last year, which is also around the same time flu infections usually peak and fall, which suggests the drivers are independent of the particular virus and strain or any interventions.
The blue dotted line below shows flu test positivity in 2019-20, showing the same turn-of-year peak and decline.
The blue dashed line below shows the same pattern for GP consultation for flu-like illness in 2010-11.
The black dotted line below shows the same pattern in the baseline (calculated from incidence in recent years) on this chart of GP consultations for flu-like illness.
Since the pattern is independent of the specific pathogen or any interventions it should be at the centre of understanding seasonal flu-like illness, including COVID-19. An acceleration to a variant-specific and seasonal herd immunity driven by the activity of the festive season is one potential explanation of this recurring pattern.