How much should the NHS worry about this winter's flu wave?

It's looks like a serious wave, but too early to say it will be worse than recent years and reporting is getting ahead of itself.

What is actually happening with flu this year

You may have seen this alarming headline on the BBC website today: “Hospitals facing unprecedented flu season, say NHS bosses”.

The article goes on to say that the number of flu patients in hospital is 50% higher than this time last year. This is true - as far as it goes. This year’s flu wave is earlier than previous years. But what matters more than the timing of the peak is the size of the peak and how long it takes to recede.

Below, I’ve plotted the number of hospital admissions for flu per 100,000 population for each of the last 4 winters, from UKHSA data.

So it is immediately apparent that this year is several weeks earlier than normal. At the moment admissions are 66% higher than they were at this time in 2022/23. But it could be that the whole wave is simply shifted a few weeks earlier so that the peak or overall number of admissions will be in line with previous years.

There is nothing to suggest from this data that the peak will be higher than 2022/23 or 2024/25 or that the decline will be longer. Now don’t get me wrong - these were serious flu winters, and the NHS will struggle to cope this winter, as it always does. How long it takes for the wave to recede will also really matter in terms of pressure on the NHS and the number of people falling ill. For instance, while the 2022/23 peak was higher than 2024/25, overall the winter of 2024/25 saw almost 50% more total hospital admissions than 2022/23 because it took so much longer for numbers to trail off (well into March/April 2025). We have no idea what the decline of this wave will look like and it is far too early to say that this is “an unprecedented flu season”.

I suspect what is driving the reporting is that the NHS wants to raise the alarm about winter - which is a very hard time every year. A&E delays and ambulance delays have not recovered since 2022. Plus it offers a framing to criticise the planned doctors’ strikes.

All that said, Japan is seeing a severe and early flu season with a new strain circulating. There is no evidence the new strain is more severe or more infectious, but it is less well matched to this year’s flu jab. I suspect we are in for a bad flu season, but I don’t think it will necessarily be worse than the bad flu seasons of 2022/23 and 2024/25.

What’s happening with Covid and RSV?

The other aspect impacting the NHS winter activity is the levels of other respiratory viruses. The chart below shows Covid, RSV and Flu plotted together since September 2023.

Covid levels are relatively low - back down to the baseline they were at for 10 months before September/October’s wave. With some luck, we won’t see a new wave during this year’s flu and RSV season, which will give some respite to the health service. It is definitely the least predictable virus our of the three though in terms of when a wave will come!

You can see RSV is increasing rapidly, but when it is compared directly to previous years (see below), it is tracking with previous winters. So there is no obvious reason that will be worse, except that its peak is more likely to coincide with the flu peak.

Summary

This certainly looks like it will be a severe flu season, but it’s too early to say it’s going to be worse than recent severe winters. The real cause for alarm is that despite plenty of data and experience, the NHS is going into this winter stressed and stretched yet again. We should have a health system that can cope much more easily with winter pressures and we just don’t.