England in biggest Covid wave in well over a year - and it's only just begun

Well the latest results of the ONS Covid Winter Infection Survey are in and they are, frankly, eye-popping. The estimated prevalence (percentage of infected people) in England as of a week ago (4.3%) is already as high as the Covid wave last December and rapidly approaching the peak of the July 2022 wave (5.8%). Given this wave has only just started (for instance subvariant JN.1 is only just reaching dominance) and that we are heading into Christmas, this wave has a lot of potential to grow significantly bigger.

Combined with the latest hospital admissions numbers and continuing strain on the NHS, this is bad news.

ONS Winter Infection Survey - how much Covid is circulating in England?

To remind people, the winter survey tests thousands of people each week who are chosen at random to be representative of the UK population using LFD tests - so results do not depend on either having symptoms or test-seeking behaviour.

Because LFDs are less sensitive than PCRs, and because even a big sample isn’t prefectly representative the population, you need to do some modelled adjustments to estimate how much actual virus is circulating (actual prevalence). The UK Health Security Agency (UKHSA) have now published their modelled estimates of prevalence and it’s not pretty. On 13 December, they estimated that 4.3% of people in England had Covid (chart from their report).

Regionally, it was highest in London, South East and East, with 6% estimated infected in London (!). That’s the highest in London since March 2022, and it’s still going up. By age, infections are highest in young and middle aged adults (below chart from their report) and these numbers will be driven higher by Christmas socialising over the past week, just before people start intergenerational mixing for Christmas. And then back to peer group mixing for New Year.

There has been rapid growth over the previous two weeks to 13 December, and given we are in a rising wave, the current prevalence is likely now significantly higher these numbers.

While we’ve had continued waves in 2023, they had been relatively modest in size - nothing like the three very large Omicron waves we saw in the first half of 2022 - until now. Below is the chart of the prevalence of Covid in the population from the previous ONS Covid Infection Survey up to March 2023 (which used the more accurate PCR tests and tested more people each week).

This current wave, driven by the now dominant “Pirola” (BA.2.86) variant, is rivalling those of early 2022. In particular, is the subvariant JN.1 which is causing large waves all over Europe and is now 43% of our sequenced cases as of 16 December. Almost certainly, by its end, this will be the biggest wave since the second Omicron wave (BA.2) in March 2022 (England’s biggest ever wave).

Hospital admissions

The good news is that hospital admissions have not risen as fast and are still about half the level they were at similar prevalence levels a year ago. However, the bad news is that they are rising (over 20% in the last week), and the more rapid infection increase in infections in younger adults might well spread to older adults over Christmas. While the autumn booster will protect, take-up is lower this year than last year (although is still almost 70%). Consistent with the ONS Winter infection survey, admissions are highest in London and the South East.

Vaccinations: most adults under 50 have not had a dose in two years

While 70% of over 65’s have had an autumn booster (with rates much lower in London), children and younger adults are less fortunate. Most children remain competely unvaccinated and most adults under 50 have not had a vaccine dose since the booster campaign when Omicron first emerged two years ago. This is likely why so many getting Covid now are reporting feeling really ill, despite it not being their first infection and being fully vaccinated. This will also be having an impact on the workforce. For instance (andecdote alert!), I’ve been hearing of lots of teachers and medical staff being off sick with Covid in recent weeks.

Additionally, it will mean thousands more people developing new Long Covid. More widespread booster vaccination could have prevented some of that. I think it is really time JCVI and the Government consider Long Covid as an adverse outcome in their determination of vaccine eligibility.

NHS England estimated that 21.5 million people were eligible for the 2023 autumn booster in England, but as of last week only 11.7 million vaccines had been delivered (there has been lower take-up in immunocompromised younger adults and health and care workers). This suggests that there are millions of unused vaccines around, which will need to be thrown away if not administered. While too late to blunt the peak of this wave, making those spare vaccines available to the general population could at least bring it down faster and add more protection as we head into 2024.

Implications

The World Health Organization designated JN.1 a variant of interest yesterday. While at the moment there is no evidence that it causes more severe disease, causing significantly more sick people (both acute illness and Long Covid) by simply infecting many more people is still bad news.

Added to that, flu is on the rise in England - the latest stats come out this afternoon. Together this has serious implications for NHS strain, especially given the ongoing junior doctor strikes.

This will be the most serious wave of infection since March 2022 by the time it’s over - and perhaps even higher. Hospital admissions are unlikely to reach the peaks seen then (almost 2000 admissions a day), but will still increase significantly. Certainly Covid is reminding us it’s not “just a cold” and has plenty of stings left in its tail.