Have I had a false positive Pcr

[winteroversummer]

I can't find anything online that might have the answer, posted previously but not many replies... any one wiser than me who can advise on what might have happened

Postal PCR Friday for my son and myself, as son had a cough, and I was showing him it didn't hurt.
No results by Sunday PM. New job starting Monday morning so really needed to see the negative test results to send him back to childminder.
Booked in for drive through PCR Sunday PM as had been told results are super quick.
Original test results came back 10pm Sunday evening, DS was negative and I was positive.
Second result came back Monday 8am, DS was negative and I was negative.
Lateral flow also say I'm negative.

No traditional covid symptoms except a bad headache for two days.

Am I positive? Do false positive Pcr happen? And why would I then get a negative?

False positives for pcr are around 0.8%. False negative for lateral flow is around 50%.

The chance is over 60 times higher that you have a false negative on the lateral flow than a false positive on the pcr.

You might have had it and are almost at the end of it?

I have had one positive PCR, one negative PCR and one negative LFT.

I know that LFT are less accurate, but surely the second PCR also said negative.

Is it not true that you test positive for the virus for ages after you've had it, too?

@Kiduknot how would that explain the positive and then the negative, please?

Perhaps you were tail end of your infection so it didn’t show on the second PCR?

Oh I see what you mean. There's the thing about not having to take a lft for 90 days after having covid isn't there, as it will show positive, though?

You ‘can’ test positive for up to 90 days after but not everyone does.

That’s a lot of pcr tests….it could be a) you had a false positive (rare but happens) b) you were at the tail end of the infection c) you didn’t swab as effectively the second time round.

Yes it was two Pcr, one positive and then one negative

Are you sure you got the tests the right way round for you and your son? It’d still be one positive and one negative for one of you but sounds more likely to be your son?

It was definitely the right way around

On both tests false negatives are much much more likely than false positives. It's actually pretty hard to get a false positive on PCR.

So I'd say its most likely you have/had COVID sorry OP

Bad headache is a classic Delta symptom. Sadly false negatives (even two) are far more likely than one false positive

I’d assume you did it properly and you have covid (sorry) nurse didn’t so it came back as false negative. Also LFT are not reliable in my experience.

Both little ds had tiny cough and a cold last week, started Tuesday and still have it. I wonder if that's covid but not shown up in their tests

They say (or used to say) don’t do a PCR more than 8 days after symptoms start, so I think testing positive for weeks may not be all that common, especially with a mild case.
Byway, There’s an up side to having had it, I think.

Anyway

Yes particularly if this is as bad as symptoms will get. I do wish the lateral flows had shown it up earlier last week, though. I took two for my job in a school and both negative on Sunday and Wednesday - worried about who I might have passed it onto

Well you did what you could, and hopefully you haven’t passed it on. Negative LFTs probably mean you weren’t very infectious.
There have been a few stories on here of people testing negative in order to fly on their first day out of isolation so it’s probably normal not to test positive for very long.

My only Covid symptom was a headache.