I’m wondering if is new variant is not showing on PCRs

[ThisSeason1]

We’re seeing a lot of cases of positive lateral flows - but negative PCRs again in the school I teach. Just wondering

There’s been nothing I’ve read anywhere to suggest that pcrs can’t detect this version.

That’s not to say that some labs are a bit crap (immensa anyone?!)

As far as I am aware they do the sequencing to detect variants from positive PCRs?

I think sometimes the window of positivity, iyswim, is very small. So the positive lateral flow is correct - the child does indeed have the virus - but by the time they get to take the PCR, the 'infectiousness' has dissipated.

Yes the new viarant will show on PCR as it has the relevant gene but you need geosequencing to identify the actual mutation

run, the other way round - lfts are the ones which only identify during a small window, that’s why you have to take them on a regular cycle, to make sure you catch that window, not ad hoc.

I’d there wasn’t a possibility that the two different nose-pokes could give different results, then why would they have you take both to start with?!
Seriously, I wonder if people aren’t accidentally sticking it too far into their brains and slowly lobotomising themselves at the same time.

How would they know it exists if it doesn't give a positive PCR result?

They can only sequence from those so of course it gets picked up

Thanks for asking this (and for the answers). We've just had some kind of virus(?) rip through the family, extended family, and apparently loads of the kids school but not a single positive PCR and it did cross my mind considering we've all had almost every single covid symptom and it's followed the same kind of curve. Sore throat, loss of taste/ smell, developed into cough, bouts of stomach upsets, chills and that weird 'feeling better' part in the middle before getting worse and finally getting over it.

Of course any other year it'd just be a viral thing, but your mind does automatically wonder!

I think it is because it is generally more difficult to administer a PCR test correctly to a child (especially a young one) than LFT. They are not always 100% cooperative. So you sometimes end up swabbing wrong areas / not hard or deep enough.

This variant has only been detected because of analysis of PCR results so I’m not sure I follow your logic…

@SweetBabyCheeses99 😂😂😂😂you have it in one!

No logic to what you’re saying. It is sequenced entirely through PCR test results.
The UK also has some of the best genomic sequencing in the world

FWIW the BBC says this:

"A PCR test for all entrants to the country is a fast way of tracking Omicron. A quirk of this variant means it gives an unusual test result (known as S-gene drop out) that will allow health officials to react more quickly than having to wait for a full genetic analysis."

www.bbc.com/news/live/uk-59443504

'This variant has only been detected because of analysis of PCR results so I’m not sure I follow your logic…'

I get this 👆🏼. And I also get that the UK has good genetic sequencing. But, a question: is it not possible that they're doing different/better sequencing in SA, and so picked up the variant where the UK has missed it ? Please don't flame me - I am genuinely asking

@SweetBabyCheeses99

I’d there wasn’t a possibility that the two different nose-pokes could give different results, then why would they have you take both to start with?! Seriously, I wonder if people aren’t accidentally sticking it too far into their brains and slowly lobotomising themselves at the same time.

They have you take two in order to improve the chance of taking a good sample (enough material, swabbing deep enough). Two crappy swabs are better than one!

If you had covid and you properly sampled from one nostril using one swab and then properly sampled from the other nostril using a second swab, there is almost zero chance that you would receive a different result from each nostril.