This is a noteworthy document provided by the UK Department of Health and Social Care in response to a freedom of information request. The most important part of the response can be found in Annex A of the letter, which is reproduced below. The original publishing of the letter can be found on this FOI website here or you can view in the google PDF viewer here.

Some comments: Isolation of an infectious agent is a fundamental concept - the principle being that until a specific infection 'thing' is isolated, it has not been properly evidenced as to its existence (i.e. isolated as in separated out from all else which is 'not it'). The original formulation of the proper scientific procedure/process is known as Koch;s postulates (https://en.wikipedia.org/wiki/Koch%27s_postulates). There also appears to be a more recent reformulation termed Molecular Koch's postulates (https://en.wikipedia.org/wiki/Molecular_Koch%27s_postulates).

Given the shutdown of the UK economy and the official shelter in place statutes issued by the UK gov, it would be expected that the DoHSC would hold extensive evidence regarding the isolation of CV19 - surely? This is the info the FOI requests, however this is answered very succinctly by the following words (in Annex A):

Your request has been handled under the Freedom of Information Act (FOIA).

DHSC does not hold information on the isolation of a SARS-COV-2 virus.

So there we have it, the FOI has been answered in full as required by law. However, there is an interesting addition which begins with the words:

However, outside of the scope of the FOIA, and on a discretionary basis, the following information has been advised to us, which may be of interest.

What is noteworthy is that it was felt necessary to add some 'justification' to the FOI response itself. We can therefore speculate that this matter went to the very 'top', given lockdown policies across the world all ultimately depend upon this principle of 'identification' (as in, does CV19 actually exist and if so what is the core direct scientific evidence to support its existence). The paragraph continues:

Most infectious diseases are caused by viruses, bacteria or fungi. Some bacteria or fungi have the capacity to grow on their own in isolation, for example in colonies on a petri dish. Viruses are different in that they are what we call “obligate pathogens” – that is, they cannot survive or reproduce without infecting a host. An explainer of these different types of pathogen (disease causing agents) can be found from BMC Biology here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648414/

For some diseases, it is possible to establish causation between a microorganism and a disease by isolating the pathogen from a patient, growing it in pure culture and reintroducing it to a healthy organism. These are known as “Koch’s postulates” and were developed in 1884. However, as our understanding of disease and different disease-causing agents has advanced, these are no longer the method for determining disease causation. It has long been known that viral diseases cannot be identified in this way as viruses cannot be grown in ‘pure culture’. When a patient is tested for a viral illness, this is normally done by looking for the presence of antigens, or viral genetic code in a host with molecular biology techniques.

Not withstanding how gracious providing such education is, the point which is being made is that specific viruses can not be isolated and thus pointed to, imaged, identified in a direct manner as say a bacteria can be. Rather (aside from symptoms) viruses can only be inferred by 'detecting/measuring the invisible' with some technical instrument. By way of an analogy, let us presume that motorcars were completely invisible and something we had never seen - but upon coming across a (visible and unattached) lone car wheel and tire - we would be able to say that motorcars definitely exist because of us having seen a wheel and tire (and that therefore we don't need to isolate and see an actual motorcar to prove its existence). However, though this might seem intuitive - really it is not imo, because nearly all of us have indeed seen and ridden in a motorcar and thus empirically know they exist, what they are and that they all have wheels and tires (at least the present generation of them).

Applying the same logic to say detecting/measuring an antigen (say one hypothesized produced by a certain virus) - when the 'thing'/virus which produces the antigen has never been seen and/or isolated, is a completely different matter surely? It remains a speculative matter and speculation is far lower on the hierarchy of evidence than isolation/direct identification, if even it is appropriate to include speculative models under the heading evidence at all?

This seems to be the real issue with the concept of viruses, as far as I understand - i.e. that it is not possible to take an image of one (at least a specific virus) and thus be able to claim, here it is - this is definite proof - something we can measure and test against and trust as real and existing. Rather the existence of viruses might be said to be almost comparable to the status which 'hearsay' occupies in law. In essence, the existence of viruses seems to be an act of belief. Even if we acknowledge that it might be possible for a machine/device to pick up their presence (despite them being invisible on an individual strain basis) - it's not a machine which the common folk are able to verify and test so again, it all seems to come down to an act of faith. 

From many hormone blood tests I have had over the years (as part of MtF transition), there is no question that lab technology is able to accurately measure incredibly small fractions of a substance - in the trillionths per gram for say the estrogen estradiol. However, this is far short of being able to determine the so-called genetic sequence/code on strands of DNA/RNA.

A question I keep coming back to is: Are DNA and viruses really a science fiction story, seeded over decades and even centuries. The Collins brothers (authors of The Ascendancy of the Scientific Dictatorship: An Examination of Epistemic Autocracy, From the 19th to the 21st Century) make the case that science fiction is the means which is being utilized to install a scientific dictatorship by the higher powers - and The Report from Iron Mountain suggests the same too in certain places, (note that as well as the original text, there is a documentary film covering the report which is well done imo - both are on archive.org).

[Note that the classic image of coronavirus such as this: https://en.wikipedia.org/wiki/Coronavirus#/media/File:Coronaviruses_004_lores.jpg are claimed by some to actually be exosomes, which are evidenced to exist in reality. The main difference between exosomes and viruses are that exosomes are considered to be related to some mechanism of a cell's normal/expected functioning (at least under conditions of toxicity when the cell is in a process of detoxifying), whereas viruses are considered pathological in the main. There is also the field of study which posits that certain organisms in blood act as pleomorphic organisms, depending on the overall 'health' of the interior terrain of an individuals body.]