Although mainstream media have been terming Deepti Gurdasani an “epidemiologist” and “peer” of Sunetra Gupta, her LinkedIn profile  and academic page  indicate this may be a weak claim. Her present role is “Senior Lecturer Machine Learning”. In any case, her publications to date  appear irrelevant to SARS-CoV-2/COVID-19.
“… Dr Sunetra Gupta who’s Professor of Theoretical Epidemiology at the University of Oxford. Dr Gupta good to have you with us again.
I mean let’s just before we speak let’s just have a listen to another epidemiologist if you don’t mind. This is Dr Deepti Gurdasani who’s epidemiologist at Queen Mary University of London. She called this three weeks ago”
“and there is actually no evidence that herd immunity exists. In fact there is ample evidence that immunity against COVID declines over time”
“Professor Gupta good afternoon”
“Nice to have you with us. Well could you just respond to one of your peers there on that point“
“Well the main thing to address is this issue of immunity declining over time. We’ve known for a while now that antibodies decline quite rapidly with time but it’s misleading to say that it implies that protection immune protection is lost with time.
It is also nonsensical to say that there is no herd immunity to, or that it’s not possible to build up herd immunity to this virus.
All other coronaviruses um build up herd immunity. By which we mean a level of immunity in the population that ensures that the risks to the vulnerable are low. So that’s endemic equilibrium herd immunity that’s how we’re using it.
I think miss Deepti Gurdasani may well have been using it in in a different context but that’s not really what it means. Herd immunity is just a level of community immunity that protects the vulnerable, that keeps risks of infection low”
“But I think that the point this group of scientists were making from this study was that yeah that might be true but you’d have to have 60-70 percent of people in that place for it to work and that would be unachievable”
“Well but first of all that is not true. There are several studies now showing that the actual level of infection that’s necessary in the population may well be below that. It’s impossible to say what the level, the threshold, the equilibrium threshold of herd immunity is because we simply don’t know how many people are already protected by virtue of exposure to other coronaviruses or you know due to their immune systems being able to deal with the virus without developing antibodies.
So this idea that the herd immunity threshold as it were has to be sixty seventy percent it is not something that you is set in stone.
Furthermore the seroprevalence, the level of antibodies you measure in a community doesn’t give you a very good idea of what the true exposure is, for the very reasons as I said which are well known although it’s very nice to have it confirmed by this bigger study, that antibodies decay very rapidly upon establishment.
It’s also known that a lot of people don’t make antibodies at all upon exposure because there are other arms of the immune system that deal with this virus such as T-cell immunity. So the picture is more complex. We have antibodies, we have immunity that is derived from antibodies, the loss of antibody in the blood does not mean that we’ve lost this antibody mediated protection because that really is stored as memory.
That’s how it operates.
That doesn’t imply that protection is being lost but furthermore there are all these other arms of the immune system which we know now through careful studies to be very important in conferring immunity.
I would say as a baseline we could assume that this virus behaves like any other coronavirus where you do get herd immunity that is to say a level of protection in the population that allows us to resume normal lives”
Source: ‘Great Barrington Declaration author refuses to back down over herd immunity’ | talkRADIO (Oct 27, 2020), https://www.youtube.com/watch?v=RZKXce5e4Xg (Fair Use)