Coronavirus

[g8ina]

CV hit home very hard today, Sally (my OH) is a care worker in a residential home for adults with acquired brain injuries, and this morning one her favourite residents passed away due to CV.

Bum

[watercooled]

I see they are rolling out an antigen test, wouldn't it have been better to find an antibody test? Being told you have had it and are now immune is surely better than being told you don't have it?

Antigen tests have been in use for ages now, they're just ramping up capacity. The antibody test is the relatively new one which needs testing for reliability before releasing it - an inaccurate test is considerably worse than not having a test. Telling someone who is immune, who is not, is worse than them not knowing and assuming they're not immune.

Also the antibody test does not replace the antigen test since there is a delay before antibodies will be detectable in the blood - so someone could have the virus and test negative on the antibody test. Again, a dangerous mistake to make.

[Jonj1611]

I wasn't aware there was a delay, do you have a source on that?

Nevermind found it, well 10 days is neither here nor there, so if you think you have had it, wait 14/16 days then test

I still think its the best way forwards.

Out of interest why wouldn't it replace the antigen test, if you have had it without knowing and the antigen test says you do not have it then aren't you going to think you have never had it? Whereas the antibody test will tell you if you have had it? If I have got that wrong I am happy to be corrected

Or is a combination of both the way forwards?

My reasons for mentioning testing is I just don't think keeping people indoors indefinitely will fly for many, maybe for a few weeks maybe even until end of April or mid May but after that I think they will have issues

[CAT-THE-FIFTH]

The most accurate tests are RT-PCR based but they are limited by the time needed for the PCR,and the time needed to transport samples. Both antigen and antibody tests,are more like initial screening tests,as anyone who tests positive and is in the risk group will probably have a followup PCR based test AFAIK.

[watercooled]

A combination of both will be used - the antigen test can detect an active infection more reliably than the antibody test because of that delay I mentioned. The antibody test isn't mush use for detecting if someone currently has the infection and should therefore be strictly isolating.

I agree testing is likely to be hugely important moving forward.

[ik9000]

CV hit home very hard today, Sally (my OH) is a care worker in a residential home for adults with acquired brain injuries, and this morning one her favourite residents passed away due to CV.

Bum

uff sorry to hear that. Condolences.

[ik9000]

A combination of both will be used - the antigen test can detect an active infection more reliably than the antibody test because of that delay I mentioned. The antigen test isn't mush use for detecting if someone currently has the infection and should therefore be strictly isolating.

I agree testing is likely to be hugely important moving forward.

is there a typo in there? seems contradictory

[watercooled]

Sorry, yes. Will fix now.

[sammyc]

CV hit home very hard today, Sally (my OH) is a care worker in a residential home for adults with acquired brain injuries, and this morning one her favourite residents passed away due to CV.

Bum

Ah, sorry awful times. Have a couple of elderly friends in care homes, doubly tough on everyone to now have visiting restrictions on top of everything.

[CAT-THE-FIFTH]

The irony is the antigen test actually uses a series of immobilised and non-immobilised antibodies. In the case of the antigen test the antibodies are raised against an artificially generated viral epitope,which is part of the viral coat.

The reason it can never be 100% accurate is:
1.)Non specific binding to the immobilised antibody which can lead to a false results
2.)The etitope even though carefully selected,might be shared with other viruses

The problem is with the compressed timeframe,there is only so much testing which can be done.



Antigen tests due to the need of monoclonal antibodes are probably more expensive,compared to an antibody test where you need to only generate the antigen,ie,less considerations with correct protein folding(which is needed when you make antibodies). But since you need to generate a viral epitope for both,the antibody test cuts out the need for monoclonal antibodies,but as said earlier there needs to be enough antibodies present in the blood,which means a more severe infection.

RT-PCR tests,which replicate the viral RNA are still going to be the most foolproof test available,because RT-PCR essentially lifts the S/N ratio. However,they are very dependent on good sampling and proper handling of samples from patients as RNA is unstable,but it is extremely sensitive.

This is why you ideally need the immunoassays to act as a broad based filter,then a follow up RT-PCR test after this.

Edit!!

Some extra reading on the assays if people are interested:
https://www.nature.com/articles/d41587-020-00010-2
https://thenativeantigencompany.com/...-for-covid-19/

Also,forgot there is a 4th kind of test,which is using something called CRISPR which is used to detect viral DNA.


https://www.nature.com/articles/d41586-020-00827-6

[Phage]

Here's an interesting read...

https://www.esquire.com/uk/life/a319...irus-timeline/

[Jonj1611]

It was an interesting read, can't say I agree with all of it however but well worth a read none the less.

[CAT-THE-FIFTH]

CV hit home very hard today, Sally (my OH) is a care worker in a residential home for adults with acquired brain injuries, and this morning one her favourite residents passed away due to CV.

Bum

I didn't read up so missed this! Sorry to hear what happened....you better keep yourself safe too!

[j1979]

looks like Dominc Cummings has it too.

I wonder if he had anything to do with, the EU bulk ordering "mishap".

[neonplanet40]

Surely not..... Hopefully his home working solution craps out. Maybe then things will get better.

[Jonj1611]

Great vid :

https://www.youtube.com/watch?v=V67qm1hqqGA