Please.
The nonsense here is how herd immunity is estimated/measured.
There is no/little consensus on how this is defined and given how polarised this is it probably never will be.
The reality is that the UK adult population is heading to 90% vaccinated. If you want to measure immunity to death from the disease as immunity we're at about 90%.
Please don't ever pretend that's not enough. I cannot fathom a model even as bad as that used in report 9 where this doesn't lead to the virus effectively dying out in a population.
This will be one of the _many_ reasons with high cases in the UK we're not seeing bodies being piled high outside hospitals.
As for actually stopping the spread of the disease itself, this would have happened much sooner had people caught it and have a _full_ immune response which makes them less likely to transmit the virus.
The point of this is that govt. expected that the virus would spread during lockdown 1 (early 2020) because people wouldn't follow the rules (it spread more due to insanely bad policy and it getting into nursing homes and hospitals and hitting the at-risk).
The initial plan was to open-up once the 'first wave' dropped reached numbers the NHS could cope with and that there would be an open/close/open/close approach as numbers rose to keep the hospital cases at manageable levels.
After seeing the high compliance we kept the lockdown and aimed for a zero-covid policy which is where Australia and New Zealand are...
We didn't see the first wave really hit. We shut down too early and too hard in lockdown 1. This led to the amount of people building an immunity being very low.
During the relaxing in summer-2020 the places that returned to normal the most ended up with higher case numbers during summer and typically this led to a slower spread and lower peak hospitalisations during the winter of 2020-2021.
This is backed when comparing the high number of cases during the summer by region with England and the initial rate of cases in the same regions at the start of winter.
This diverges once winter properly set in as other factors became dominant. This is not rocket science
In the winter of 2020-2021 the UK locked down too late and more people at risk died.
This being too late was a combination of factors "it only kills over 80s" from Boris, the lockdown being too effective, the vaccine being around the corner and so on...