Is a lateral flow test thought to pick up anything other than Covid?

[DogBirthday]

I've been told by three people now (none with any scientific background) that lateral flows pick up some colds, strep throat etc.

This isn't the case, is it? I've not read anything suggesting this from anywhere sensible.

They don’t pick up most common viruses so shouldn’t detect common colds etc.

However, in the last few weeks there seems to have been an issue with a higher than expected proportion of people testing positive on lateral flow but negative on PCR, which is being investigated by the public health authority.

It is not yet known whether this is because of a problem with lateral flow tests, a problem with PCR tests or something else.

I saw an interesting post on twitter about this. They are cross tested for the 3 main other cornonaviruses to make sure they don't react. However, there are a couple that can't be totally ruled out, OC43 and HKU1.
I don't really know why, just repeating what I read

I've now had two different occasion where I have been positive on lft (faint lines) but negative pcr so it would not surprise me they do pick something else up

No they don’t pick up cold viruses etc, they are specific to the sars-Cov-2 virus. The reason for positive LFDs and negative PCRs is to do with the specificity and sensitivity of tests (which I don’t 100% understand but basically explains false positives in LFDs)

I think the answer is we (by we I guess I mean the scientists/ experts) don’t fully know , but it is possible..

At the moment there does seem to be an unusually high prevalence of positive LFTs with negative PcRs, (a growing concern which is currently being investigated by the gov). There are a number of theories about what might be causing this, one of which is that LFTs are picking up virus proteins from other common coronaviruses which are also in high circulation at the moment (changing seasons etc).

@Igotjelly that's assuming that the LFDs are wrong rather than the PCR.
We've had at least 10 positive LF from 3 different brands, so I think it unlikely they are faulty tests. Either they are cross reacting to something that isn't covid, OR the two PCRs each we have done are false negatives.

@Tinysnickers

I saw an interesting post on twitter about this. They are cross tested for the 3 main other cornonaviruses to make sure they don't react. However, there are a couple that can't be totally ruled out, OC43 and HKU1. I don't really know why, just repeating what I read

Interesting! What are OC43 and HkU1?

They are other coronaviruses that have been in circulation for a while now. I read an article a while back that suggested people who were feeling like they were 'immune' to covid may have some immunity from having had OC43 before. No idea how true it is!

[quote Tinysnickers]@Igotjelly that's assuming that the LFDs are wrong rather than the PCR.
We've had at least 10 positive LF from 3 different brands, so I think it unlikely they are faulty tests. Either they are cross reacting to something that isn't covid, OR the two PCRs each we have done are false negatives.[/quote]
... or there has been a mutation. That's a possibility, yes?

We don’t know. One scientist on Twitter posted this graph, suggesting it’s potentially possible that some other coronaviruses may occasionally get picked up on LFTs.

twitter.com/BallouxFrancois/status/1447496215483015173?s=20

Balloux thinks this is more likely than a new covid strain that is undetectable on PCR, but I don’t believe there’s a consensus on that yet.

Interesting! What are OC43 and HkU1?

They’re two of the endemic coronaviruses that can cause the common cold (or, less commonly, more severe infections such as pneumonia)

Balloux thinks this is more likely than a new covid strain that is undetectable on PCR

But it doesn’t explain why quite a few eventually test positive.

so dd is currently positive (twice) on LFT, but her pcr came back this morning as negative.

She has mild generic symptoms, and has had all the rotten colds going round in the last month. Has felt rough over the weekend (headache and sore throat) and did a LFT on Sunday.

She has just told me that she now cannot taste anything.
I think she has covid. But the pcr tests says not.

My understanding of the current issue is not so much that the LFT is positive and the pcr negative, but that a second pcr 4-5 days later shows positive, so the LFT seems to be reacting before the pcr test.

No idea what to do with dd now.

@Siepie

We don’t know. One scientist on Twitter posted this graph, suggesting it’s potentially possible that some other coronaviruses may occasionally get picked up on LFTs.

twitter.com/BallouxFrancois/status/1447496215483015173?s=20

Balloux thinks this is more likely than a new covid strain that is undetectable on PCR, but I don’t believe there’s a consensus on that yet.

However other scientists last night on Twitter pointed out an error in his explanation:

twitter.com/bealelab/status/1447268162702127104?s=21

I think it’s the PCR tests that are messing up, not the LFTs. But who knows why?