Possibly explain why so many cases are being reported as positive as well. If the virus is there but in a smaller and less potent amount then technically it would pose much less risk than 5 months ago. In much the same way the flu doesn't run rampant but still possible for someone to catch it at any point of the year.
The following is based on the premise that it's mostly older people who get really sick, and ultimately die. My guesswork assumes that only old people get admitted to hospital, which is plainly wrong, but a ) the error will be similar for both timescales and b ) probably isn't massively wrong anyway
Very roughly, looking at the graphs, in weeks 33 and 34, about 2000 people aged 60 or above tested positive. Roughly 600 people were admitted to hospital in England in the last two weeks, so about 30%
For all weeks, the same numbers are about 115,000 and 113,000, so near enough 100%
On the face of it, that suggests that, as a %, less infected older people are ending up in hospital. But, certainly until the peak, very few people were being tested unless they were admitted to hospital, so the earlier numbers excluded anyone who was either asymptomatic or had only minor health issues. I think I read somewhere that about half those testing positive in care homes recently were asympomatic, so, if I havn't dreamt it, then that immediately brings the two numbers closer together.
It may be that I'm interpreting the numbers to support my view that the virus hasn't changed much ? But I think the data is purely showing us that, in general, older people are taking far more precautions now ( plus care homes are far safer ), and so aren't getting infected as they were in March to May. If those precautions for those at risk are relaxed, then we'll probably end up with increasing numbers of hospital admissions.