Positive lateral flow negative pcr

[Webb27]

Hi I wonder if anyone can help advise. I'm a primary teacher and three of my class tested positive for Covid on a pcr this week. I took a lateral flow test after school on Friday and it was negative. I woke up yesterday morning feeling fatigued, aching limbs, a headache and a cough. I took a lateral flow test and it was positive. I booked a pcr yesterday but it came back negative. I have taken two further lateral flow tests today and both are positive. Also I'm double vaccinated. What are the chances of a false negative pcr test ? Thank you

About 30% I believe, depending how soon after contact the test was taken. If taken on day 1 of contact for example chances of a false negative pcr is 100%! Chances of several false positive lft miniscule.

I'd go for another PCR I think

Thank you both. That's what I'm going to do.

If taken on day 1 of contact for example chances of a false negative pcr is 100%!

That is not a false negative PCR, that's a correct negative PCR, it's just rightly not useful - it's like taking a pregnancy test after the egg is fertilised but before implantation, absolutely impossible for the test to be positive as the thing being tested is not the thing that has happened yet.

It is nothing like 30% in the infectious period, when an LFD would be positive, it is considerably lower than that, most of the failures then are in the gathering of the sample. But it is non-zero, there's always a chance, and it's certainly high enough that it could be a genuine negative. How you want to act on the information is all up to you, you say you are ill anyway, so I would certainly not be working until you feel better whatever you do.

Which is actually likely enough in a double jabbed adult, low viral loads, short infectious period is the likely course of the infection.

It is nothing like 30% in the infectious period, when an LFD would be positive

You're right, it's higher, more like 38%

Pcr came back positive this morning at 4am

Similar happened to someone I know! Tested positive with no symptoms on a lateral flow - took a pcr - negative - took another lateral flow when some symptoms arose - positive - pcr then positive! She works in childcare so it causes all sorts of confusement . Thankfully it didn't spread to anyone else.

I would speak to someone to seek advice. It wouldn't hurt do another pcr but they aren meant tj be the most accurate.

People have been known to test positive on a lateral flow but not the pcr where's usually it's the other way round.

Just seen update. Hope you feel better soon!

Thank goodness you took another PCR.

Hope you are and remain well, and being off doesn't cause you too much of a headache.