Covid Situation Report: Jan 5, 2024

Update on Covid providing information on prevalence and hospital admissions for England and its regions. This post is best viewed using the browser or Substack app.

Introduction

This is the sixth of the weekly Covid Situation Reports I plan to publish over the Winter 2023 / Spring 2024 season.  Each report provides an overview of the present Covid status in England and its regions using a standard set of interactive charts.   For those who want a bit more detail I take a deeper dive on topics of interest each week.  This week I look at the longer term trends in hospital admissions for Covid compared to other respiratory viruses, as well as a quick update on Covid variants.

Summary

There are early signs that the present Covid wave has peaked as daily hospital admissions declined slightly in the past week. Next weeks Winter Infection Survey should confirm if this is the case.

Hospital admissions for Flu continued to increase and are now higher than for Covid, placing hospitals under increased pressure.

Looking at the long term trends shows that Covid hospital admissions are higher than for other respiratory viruses and do not yet follow a seasonal pattern.

The JN.1 variant (Pirola) continues to be the dominant variant in England and has driven the recent growth in Covid infections.

A reminder that although the main Covid booster program is closed in England, UKHSA advised that you may be able to get vaccinated at a walk-in site which can be found at the following link until the program closes on January 31, 2024

Present status of main respiratory diseases in England

After the Christmas break the UKHSA weekly Influenza and COVID-19 surveillance report returned this week. The following chart, based on UKHSA data, shows the positivity rate for the main respiratory diseases monitored.

Covid, RSV, and Rhinovirus positivity rates all decreased in the latest reported week. However, the positivity level for Flu increased although not as fast as in the previous week and does not look to be approaching the high levels seen in Winter 2022.

The next chart shows weekly hospital admissions per 100,000 people in England for the main respiratory diseases. Note that no data is available for Rhinovirus admissions.

Flu had an appreciable week on week increase in hospital admission rates with an increase of 33%. Weekly Covid admissions also increased by 8% but we will see later that the more granular daily admissions data showed a slight decrease. The good news is that at present these hospital admission rates for Flu and Covid are lower than in Winter 2022/23.

Longer term trends for respiratory diseases in England

This section provides an historic perspective to the Covid epidemic by looking at the trend in the hospital admission rates of the main respiratory infections over the past seven years.

The following chart shows the weekly hospital admissions per 100,000 for RSV, Flu and Covid in England from January 2017 to Dec 2023. The grey bars labelled LD 1, LD 2 and LD 3 mark the three national lockdowns.

Let’s start by looking at the trend for hospital admission rates for the main respiratory viruses before Covid emerged in March 2020. The chart shows that between 2017/18 and 2019/20 RSV and Flu followed a clear seasonal pattern with peaks in December and January respectively. Although these peaks are much lower than the subsequent Covid peaks it is important to remember that respiratory diseases, particularly Flu, are a major cause of excess winter deaths. Deaths from Flu are difficult to assess as they are usually associated with pneumonia but UKHSA estimated 22,000 deaths from Flu for the 2017/18 Winter wave. Typically, Flu vaccines are between 40% to 55% effective at preventing hospitalisation for all ages but the 2017/18 flu vaccine was only 15% effective contributing to a higher number of deaths.

Turning now to the trend for RSV and Flu after the emergence of Covid. The measures taken to mitigate the impact of Covid (staying at home, testing and isolation, masks, etc.) reduced the number of people catching Flu significantly. This is because seasonal Flu isn't as infectious as Covid. The chart shows that the Covid mitigation measures worked well as there were no seasonal peaks for Flu in the Winters of 2020/21 and 2021/22.

Unfortunately, Winter 2022/23 saw the highest number of hospital admissions for Flu for many years. Three main reasons have been put forward for this significant rise in Flu hospital admissions.

First, the Flu strain circulating was particularly severe. The dominant strain in 2022/23 was Flu Type A which is associated with more severe seasons—especially among the very young and older adults. Secondly, the Flu vaccine given that year was less effective against Flu Type A than usual. Early estimates found that vaccine effectiveness preventing hospitalisation against Flu Type A was between 27% to 44%. Finally, loosened Covid restrictions exacerbated the Flu's rebound. As we have seen, there were no seasonal waves for Flu admissions on 2020/21 and 2021/22 and that meant fewer people, who are not eligible for vaccination, were exposed to and developed natural immunity to the Flu.

Let’s now turn to Covid hospital admissions which we can see follows a very different path to the seasonal respiratory virus. First the disease burden from Covid is much higher than for RSV or Flu with non-seasonal waves driven mainly by new Covid variants. However, the number of hospital admissions for each Covid wave is reducing. This is mainly due to the effectiveness of Covid vaccines for those eligible for vaccination and immunity arising from exposure to Covid for those not eligible. Although hospital admissions for Covid are reducing over time it’s important to remember that the clinically vulnerable remain at risk and the longer term health impacts of having Covid can be severe.

What happens next with Covid remains uncertain. It seems likely that at some point it will become a seasonal respiratory virus like other Corona viruses, but Covid has shown that it can still evolve and throw up nasty surprises. For a fuller discussion on this topic I recommend reading Dr Adam Kucharski’s substack article on Covid evolution.

England Covid hospital admissions and bed occupancy

The following dashboard shows the daily numbers for the key Covid metrics for hospitals in England. This allows us to pick up recent trends better than the weekly aggregate admission rates presented above.

Unlike the weekly admissions data, the dashboard shows that daily hospital admissions decreased slightly last week. However, normal and mechanically ventilated beds occupied by patients with Covid increased by 10% this week.

The following dashboard gives the Covid hospital admissions per 100,000 by region and shows a mixed picture. Most regions showed decreasing or unchanged hospital admission rates in the latest week.

There are strong signs that the waves of Covid hospital admissions in the London and South East regions have peaked. Also the Midlands, South East and South West regions admission rates have plateaued. The only regions with increased admission rates are North East and Yorkshire and the North West.

Overall the latest data for hospital admissions indicates that the present Covid wave has peaked and the good news is that this is at about half the rate it was one year ago. Next week we will see the data from the Winter Infection Survey and this should give a clearer indication of what is happening.

Covid Variants

The World Health Organisation (WHO) recently classified JN.1, also known as the ‘Pirola’ variant, as a separate variant of interest (VOI) from the parent lineage BA.2.86. The WHO risk report concludes that although the JN.1 variant has a significant growth advantage it is not more severe than other variants.

The following chart shows that the BA.2.86 family, which includes JN.1, has outcompeted all other variants and continues to be the dominant variant in England.

At the moment, the number of sequenced cases is low so there is some uncertainty over the prevalence data. However, it is certain that the Pirola variant is the cause of the recent wave of Covid infections.

In conclusion

The recent rise in Covid hospital admissions appears to have peaked but Flu admissions continue to rise and now exceed Covid admissions.

Over the longer term, Covid has been a more significant health burden than other respiratory diseases but is showing signs of moderating, although it is not yet a seasonal disease.

As always, if you have any comments on this Covid Situation Report or have suggestions for topics to cover then please post a message below.