LFT negative, PCR positive

[Askinvillarblues]

I’ve seen lots of posts where the lateral flows have been positive and PCRs negative, but has anyone experienced the opposite? My son started with symptoms and subsequently tested positive on a PCR, but all his lateral flows have been negative . How will we know if the rest of us are positive but asymptomatic if the lateral flows aren’t picking it up?

This is why I'm anxious about LFTs, my DH ALWAYS tests positive but has negative PCRs

LFT negative PCR positive is quite common.

Close contacts are still advised to get PCRs aren't they? Or am I wrong...

Yes it's common. Happened to DS and I last year.

@JanglyBeads

Close contacts are still advised to get PCRs aren't they? Or am I wrong...

No, only if they develop symptoms.

Pretty common in some circumstances. Lft tests can be really accurate sometimes but in others not so much. It's bizarre!

Apparently it probably means you have it but aren’t infectious. So some doctor was saying in the paper yesterday

@JanglyBeads

Close contacts are still advised to get PCRs aren't they? Or am I wrong...

You're not wrong www.gov.uk/government/publications/covid-19-stay-at-home-guidance/stay-at-home-guidance-for-households-with-possible-coronavirus-covid-19-infection

@JanglyBeads

Close contacts are still advised to get PCRs aren't they? Or am I wrong...

They aren’t unless they are required to self isolate. It’s 7 days of lfts. I’m assuming England here.

I was a close contact and was told to do seven days of lateral flows

We’ve been told to do the 7 days of lateral flows and don’t need to isolate as all fully vaccinated - I’m just worried that in theory we could be walking round spreading Covid without realising, given that my son is clearly positive (symptoms and a positive pcr) but his lateral flows are all negative. We are being careful anyway and not going anywhere unless absolutely necessary, but I’m wondering whether to book in for pcrs later in the week to rule it out. It was almost easier before all the rules changed and everyone in close contact had to get a pcr!

I’m just worried that in theory we could be walking round spreading Covid without realising

Yes but that is the case for everyone. LFTs pick up some cases where it detects someone is contagious with enough viral load to trigger the test. It won't pick up all cases but detecting some is better than none.

Your son has symptoms, thus why I presume he had the PCR. If you have a negative LFT but have symptoms, then I expect you would get a PCR.

@JanglyBeads

LFT negative PCR positive is quite common.

This.

You’re much more likely to get a false negative on a LFT.

LFTs aren’t that accurate! They never have been.

If they’re positive, there’s a high chance they’re correct.

If they’re negative, there’s a pretty good chance that it’s wrong.

Hard to wrap your head around but that’s the issue. That’s why they say if you’re got symptoms get a PCR to be sure.

PCRs are more sensitive than LFTs are. But they take longer to get results, and also cost more to process.

LFTs are good at picking up the really infectious cases. Especially ones with no symptoms.

Can’t explain why some test positive on LFT but negative on PCR, assuming samples taken immediately after each other (so not contaminated by food/drink etc or infection waning).

@Askinvillarblues

We’ve been told to do the 7 days of lateral flows and don’t need to isolate as all fully vaccinated - I’m just worried that in theory we could be walking round spreading Covid without realising, given that my son is clearly positive (symptoms and a positive pcr) but his lateral flows are all negative. We are being careful anyway and not going anywhere unless absolutely necessary, but I’m wondering whether to book in for pcrs later in the week to rule it out. It was almost easier before all the rules changed and everyone in close contact had to get a pcr!

Yes this has happened to me recently.

DS tested positive. My LFTs were negative but had a PCR just in case which came back positive. LFTs started showing positive a few days later.

I think they're just not as accurate or sensitive.

Day 11 and still testing positive on them though!

I was negative lft with a positive pcr. No lft positive in the subsequent days.