UKH

I've been looking through https://www.covidfaq.co/ and it seems to me that it is generally neutrally written and well argued.

However, one gaping hole seems to be on asypmtomatic/presymtomatic transmissions of COVID. Does anyone know the current consensus on this one (if there is one).

As this is a key driver in the mask use policy and social distancing policy it seems odd it is not addressed at all. Can anyone better read than me provide an informed angle?

Covid deniers point to this study which certainly makes for eye-opening reading on the topic.

https://www.nature.com/articles/s41467-020-19802-w

How is someone who refers you to a scientific paper that doesn't question the existence of Covid, a Covid denier? 

Ok maybe Covid skeptic is a better term. Do you have anything useful to input into this topic?

Helping you to not alienate so called 'covid deniers' so that they may feel more welcome in explaining their views is quite useful, wouldn't you say?

Not alienate Covid deniers?

Am I reading this right?

https://www.bmj.com/content/371/bmj.m4851

Thanks for this.

Having looked a little more at the paper I linked: 10 million people tested in Wuhan with only 300 asymptomatic cases and no new symptomatic cases found rather undermines the PCR false positive argument doesn't it!...

Not my words

Clearly not.  Maybe try re-reading it?

The problem is that one man's symptoms are not another's.  Jersey updated their symptom list a couple of days ago to include the following:-

nasal congestion

conjunctivitis (also known as red eyes)

different types of skin rash

They're testing pretty thoroughly compared to most places (1000 per day from 100k population) and reckon on about a 2:1 symptomatic/asymptomatic split in their confirmed cases. I don't know if they update the case status if an asymptomatic person becomes symptomatic.  I'm confused about your 'mask use and social distancing' comment - surely everyone has to abide by those rules whether they're symptomatic or not, and thus asymptomatic spread in those situations is affected as much as symptomatic spread?

I mean it drives policy. If you assume no asymptomatic spread than the case for masks etc. is less pronounced. There is also of course the pre-symptomatic scenario you allude to.

I have been pointed at this paper which I am reviewing now: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2774102

I'm absolutely no expert on the issue of PCR, but it possibly doesn't undermine the argument. 

In an environment devoid of COVID, you'd naturally expect zero returns as a result of PCR testing.  But in an environment (i.e city, building, etc.) where it exists, the point being made (I believe) is that PCR can return positive results (in effect reporting latent traces of COVID) even though 'infection' doesn't exist. 

Obviously, this draws in to question what 'infection' actually means.  A single viral strand sat in the mucus of your nose, but that is maybe not viable, technically would constitute infection.  And the argument is that this may also return a positive PCR test.  But that this infection may not be the same as having sufficient intact covid in your system, or in sufficient quantities, to result in illness (asymptomatic or symptomatic) and/or transmission.

The Wuhan testing potentially gives a maximum false positive rate of 0.00003%. The false negative skeptics (casedemic) have been suggesting false positive rates thousands of times higher than that.

I get that, but isn't the article simply indicating the prevalence of positives, false or otherwise, in an environment were almost no covid is present anyway (a two-week period in May after rigorous lockdown)? 

The argument that PCR tests have potential to return false positives isn't really made on the assumption that they detect positive samples where no covid exist - i.e a true false positive.  It is that the degree of sensitivity is such that you are guaranteed positive results even where covid exists at levels that potentially result in no illness.  An analogy would be a blood alcohol drink driving limit at or near zero, with the result that everyone tested will likely be positive, either because they had a drink a few days ago or natural background breath alcohol normaly present.

Amongst the 10 million tested, were 35000 people previously infected. A 107 of that subgroup came back as positive which rather negates the longterm dormant RNA shedding argument also.

Also of note is that the PCR test in that study used 2 not 3 gene targets, unlike the UK one.