I am new to this forum and have a unique issue which I am hoping someone out there may have experienced too. I am 33 y/o and have CCP-positive Rheumatoid Arthritis. Fortunately, I am in remission and now only take Hydroxychloroquine but have spent a number of years previously on Methotrexate.
I am fully vaccinated against Covid-19 after receiving my second Astra-Zeneca vaccine in April 2021. I have taken 4 lateral flow tests (3 on the same occasion and 1 on a separate), all of which have come back positive. The test line has appeared faintly in the during of the 30 min test window. Of course, I have then routinely booked a PCR for either the same, or next day and isolated before the test and until the result. However, the PCR tests have consistently come back negative. My understanding is that PCR is the "gold standard" test and far more accurate, so while I am confident in the result, I am now concerned that something in my body is causing these false positives.
I spoke with NRAS, who suggested I reach out on here to see if anyone else has an experience similar. I understand false negatives are common but false positives are rare.
A quick google (although I am mindful that I am not from a medical background) and some information from a registrar at Kings, suggests it could be cross-reactivity of antibodies.
Would love to know if anyone else has had a similar experience and if they received any useful advice yet?
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MelissaM1987
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Hi Melissa. I recently took 3 lateral flow tests. Two negatives and 1 false positive. I am taking sulfasalazine. Not sure this is helpful but here is a little bit of data if you are informally gathering some.
Thanks so much for your message - yes I really am just trying to find someone out there who has had a similar experience to mine. I have spoken to NRAS and they are going to refer the case onto the British Rheumatology Society - it's hard to know if it's even related but I thought it would be a sensible starting point as it's the only significant medical condition I have.
Hi Melissa,Two thoughts occur. First, have you had covid in the past? People who have had covid tend to test positive on the lateral flow tests, at college they were asked not to take the LFTs.
Second, you say the test line appears faintly 'during the 30 min window'. Does this mean that the line is only there in the first 30 mins and then disappears? If so, that is a negative test because the test can only be read 30 mins after you put the drops on the cassette.
If neither of those apply, then I'm out of ideas. I've had two LFTs per week since early March and not a single false positive. Most people at work that have tested positive in the LFT have then also tested positive in the CPR, as you say false positives are rare.
Thanks for your message. I don't think I have had Covid in the past - that said, I accept that I could have been completely asymptomatic. However, these tests have all had false positives (from different batches and my husband uses them with no issues) since my second vaccine and I work from home. Therefore, day-to-day I am rarely in settings that I would say put me at particularly high risk of catching it.
When I say 'during the 30 minute window', I mean that the line does not immediately develop when I do the test - it usually starts to show at about 15 minutes or so. However, it is undeniably there at that point which is why I also have to take a follow up PCR.
I guess I am just trying to find other people who have had this experience because I find it hard to believe I am the only person out there. Also, my family live abroad and it's possible I could be given a spot check lateral flow at the airport on their side which is quite worrying given I have never produced a negative test using one before.
My nephew had a false positive too he has autism and tested positive at school the only one apparently. He , like you followed up with a PCR and that was negative so yea it is possible to get false positive results from lateral flow tests. I’m hoping they’re very rare but not unheard of. As I’ve been shielding for best part of two years I’ve only had to take one test just to prove to doc that the chest infection I had was just that and not covid as I’m CEV so I can’t give you my personal experience.
Hi there, thank you for sharing your nephew's experience. I definitely agree that false positives are possible, I just find it strange that all the lateral flow tests I have done come back positive. Of course, I am grateful for the PCR confirming negative though.
I'm so sorry to hear you have been shielding for so long, I can't imagine how difficult that must have been. I very much hope the end is in sight and you'll be able to enjoy a sense of freedom soon.
Just checking you’re not eating or drinking beforehand? I’m a teacher and a couple of teens at school realised if they did a test after having orange juice or a fruit shoot that it could come back positive on the LFTs! Cheeky monkies eh?!
I have read about this too. It's so naughty and a real step up from when I was little and we used to do the old thermometer on a hot water bottle trick (which my Mum never fell for!). I haven't been eating or drinking that close to doing them, although some of them weren't first thing in the morning. I would have thought it wouldn't be so consistent a pattern though, unless it is reacting to any bit of food/drink I have had at any point in the day? That does seem very sensitive if that's the case though.
Hi Melissa. I too have had this happen to me. I took two lateral flow tests 12 hours apart from different batches and both were positive. My subsequent PCR test was negative. I reported ut to my rhuematology department but they hadn't heard of it before.
Hi there, thank you so much for coming back to me. I am sorry you have had this experience but am also relieved to have come across someone else. I'd be interested to understand (and of course if you don't mind sharing) if we have the same type of arthritis (I am RF positive, anti-ccp positive RA). If so, I wonder if we could flag this together to our Rheumatology depts. I have written to the British Society of Rheumatology and the Royal College of Pathology, neither of which have found it of any clinical interest. Thanks, Melissa
That's interesting. I have let NRAS know they said they will bring it up a the next forum they have with the British Society of Rheumatology. If you are comfortable, it might be worth letting them know your experience too. We can't be the only ones out there!
Hi. thanks.Yes I'll contact them. I let track and trace know at the time as well. They were going to flag it up too. I was speaking to someone on a RA Facebook.page that had the same issue. Also my RA nurse said she'd mention it to my consultant.
Hi there. I have just received a message from the British Society for Rheumatology who said they will refer it onto their Covid steering group for consideration. It's the closest I have got to some kind of acknowledgement so far! Their email address is: bsr@rheumatology.org.uk if you feel you want to share your experience too.
Hi there. Thanks for doing that. I emailed NRAS yesterday. I also did another lateral flow test yesterday just out of interest an again it was positive so somethings going on. !
Definitely something up with all this! I have been doing weekly PCRs instead but I'd really like some kind of letter from a GP that I can carry on me. I managed to get an appointment tomorrow and will let you know what they say.
My Dr has never heard of this either but it going to write to the virology department at St Thomas' hospital to flag is as an issue. To be completely honest, it wasn't the most helpful phone call but the Dr agreed looking at RA antibodies was a sensible approach. The downside is he said it is unlikely to be a quick response on this. He seems to think if it was related to RA, it would have been noticed already but I wonder how much data there is available? It affects around 1% of the population, of which a significant group will have been shielding. I'm not sure how regularly these tests are being done among shielding groups.
As I'm retired and live on my own - I have virtually self-isolated, so have had no need to take a lateral flow test. However, I will be very interested to see whether this is reported on.
I’m RF positive and have been doing lateral flow tests twice a week for several months and I’ve not had any false positives. Hope you work out what is causing yours.
Hi Melissa, I had 3 lateral flow tests recently and all showed a positive result. PCR test a day later was negative. Have had first AZ jab but unable to have 2nd due to very severe reaction. Am taking 5mg Prednisolone at the moment.Believe I caught covid in December 2019 but was too early for a test at the time. My RA symptoms have been far worse since then.
Hi Lizzie, thanks for your message. I am glad to hear you don't have Covid this time, although is sounds like you are having similar lateral flow issues to me. I am so sorry you have had issues with the vaccine, I really hope you find a solution to that as it must be scary not being fully vaccinated. If you don't mind me asking, what type of RA do you have? I am anti-ccp postive and RF positive - I'm just trying to find if there is any kind of pattern developing there.
I went to an international trade show In January with a big delegation from China prior to the virus announcement. I was unwell for weeks afterwards and so was my husband. My RA has been worse since then. I had both vaccinations this summer, AstraZeneca with a booster due early next year. My RA has flared up and remained bad since the vaccinations. I’m back to taking pain medication most days now and wearing wrist/ knee supports. I hope it fades soo as it’s getting me down.
I'm in exactly the same position Melissa. Four lateral flow tests this week have been positive showing very faint second lines. Two PCR tests which have been negative. As a family we are having to isolate even though I'm getting negative PCRs. I've left a message to speak to the rheumatology helpline and spoke with NRAS today. They told me about this post. I'll be interested to see if my Rheumy Nurse knows any more about the Antibody issue when she gets back to me.
That's such a pain! I was of the understanding that if you get negative PCRs, you shouldn't have to isolate (according to Track and Trace), but I don't know how that translates to peoples workplace rules etc. I am anti-ccp, RF factor positive RA - if you don't mind me asking, what type do you have? I just don't believe there are so few people having this issue that it hasn't been flagged. My GP wrote to the immunology department at St Thomas's with my dilemma and I will report back any findings.
Yes I am and strongly anti-CCP positive. I do lateral flows twice a week for past three months for my work. All negative except this week. It would be a long process for the scientists to work out if there is a link but all we can do is feed back our experience. So interesting that other people have experienced this too.
UPDATE! After getting nowhere, my Rheumatology nurse suggested I try swabbing just my throat for a lateral flow test and just my nose for another. As you can see, negative for throat and positive for nose. I did this because I got a negative PCR test this morning, so it was a sensible time to try this knowing I don't have Covid. It has been referred to virology urgently.
Lateral flow test using a throat only swab is showing negative and a nose only, positive.
Update number 2!Virology came back to say that this is a medical phenomenon that they are aware of but as yet, do not know why this is happening to certain people. No conclusive link can be drawn between this and antibodies relating to RA. My GP has written a letter for me to carry when travelling, so I feel more comfortable getting on a plane to go and see my Mum and Dad, knowing I have something to show if I am spot checked at the border. One step closer to me and my family being reunited.
This is interesting Melissa. I did lateral flows minutes apart using two different brands. The innova test showed a faint second line but the government issue lateral flow tests were consistently negative and three pcrs were negative too.
I tried that but still delivers a false positive. However, weirdly, it's my nose that causes the false positives so I have an exemption recommendation letter from my GP to carry when travelling. Virology at St Thomas' hospital said it is a phenomenon they know about but don't yet know why. Hopefully in time things will become clearer!
I’m so relieved to see this! I have had the exact same thing twice now. Once in June and again last week. In June I felt unwell and had a bad headache. A lateral flow showed a weak positive. I took a PCR that afternoon. Later I had a clear positive lateral flow. The following day I received a negative result for the PCR but tested positive twice more on Lateral flows. I eventually tested negative around 4 days later. GP advised that I probably had COVID (I wasn’t convinced). At this stage I had had one Pfizer dose.
Last week I took another lateral flow test as was feeling a bit under the weather again. Long story short over the last week I have had 5 weak positive and 2 strong positive LF tests and 2 negative PCR results. I have now had both Pfizer jabs. I have anti-ccp and RF positive RA. I take Baricitinib. I did the tests without food or drink influence. The strongest positive I had was one done first thing in the morning after waking. My GP and Rheum Nurse don’t know why this is happening either. I too have the worry that false positives will cause me difficulties in the future. I’ve already had to postpone steroid injections in my knees because of it. Please do keep us updated on your progress. Thanks, Claire x
Hi Claire, I am so sorry you're going through this too but so relieved to have found someone in the same position! It's been a really troubling few weeks trying to be acknowledged and listened to. I don't know where you are based but I had a good breakthrough with my GP, and he urgently referred it to the virology dept at Guys and St Thomas'. They said they are aware of it but it's so rare they don't yet know why it's happening. My GP has written a letter to say I should be exempt from lateral flows as a first line of testing and should be offered a PCR instead. I am travelling to Greece to see my Mum and Dad on Sunday and the Greek Embassy said that it was an acceptable letter, and so I would highly recommend you try and get one if you can.
I would also ask, if you don't mind, to write to NRAS. They have been brilliant and have flagged to the British Society for Rheumatology, but they have said they don't have enough evidence to find patterns.
Out of interest, have you tried doing one swab from your nose and a separate from your throat?
I too was initially told I probably had Covid, but I had received two doses of the vaccine by this point so I thought it was unlikely.
I really hope you get to the bottom of it and do let me know if there are any developments on your side.
Thanks for the reply Melissa. You certainly seem to have made better progress than me. The GP I spoke with just seemed baffled and gave no indication of how I could resolve things. I will contact NRAS (if you could PM me with details of who you have contacted that would be helpful.) I hope you have a wonderful trip to see your family.
If I am being honest, I think it's because I had a massive meltdown on the phone. The thought of having to isolate because of a false positive lateral flow test and not see my parents (as you can imagine it has been a long time since I have been able to see them) really got to me. I suppose on the plus, it got things moving though. I'll send you details of the lady I spoke to at NRAS. I think another person on here has got in touch with the same thing too. Hard to say if it's all connected but (thankfully) it's my ownly significant health issue, so I thought it was a sensible place to start. x
Hi Melissa - it is a frustration - as I know someone who had to fly out urgently on a business trip - the morning of the flight got this false positive and he was fully vaccinated - did contract covid post vacinne - had to spend over £500 as had to do another test at another company that came back fine - able to board the flight! It was an absolute nightmare and stressful too.
Interesting enough, today, the news is all about these tests and rip off charges.
Not sure how useful this is but definitely something that needs to be looked into overall.
My wife too did the LFT on Friday 20 /8/2021 with positive results . she did two more one in the evening and another on Saturday morning 21/8/2021 showing positive result . As we were due to go to a very important wedding of my wife's niece . we rushed and got a PCR test on Friday evening in the hope of getting the result the following day before the wedding , and paid £200 ie £100 each . Unfortunately we did not get the result until Saturday evening at 10pm with both of us showed negative PCR test . Therefore , we had to missed the wedding with a devastating impact on my wife , as she was standing for the Brides mother . As the bride's mother , my wife's sister , had passed away years a go with breast cancer. It is a shame that the government is not publicizing the true accuracy of the flow flow test , causing this kind of agony for the public and is only interested in making money out of the public misery . !!
I am so sorry to hear you and your wife have been through this, and all for nothing. That really is so upsetting and awful. I agree, there is a lack of honesty around the accuracy of these tests and I don't know if you saw my pictures above but if I only do a throat swab then I can deliver a negative result but the moment I do a nose swab it comes back positive. I managed to get a letter from my Dr to say lateral flow tests should not be used in my first line of testing, but it doesn't really solve the ongoing issue around travel for me (e.g. if I went on a city break, I have to factor in the time to get a PCR before coming back and not all can guarantee a 24 hr turnaround). I would say it is worth reporting your wife's experience though, incase there is some kind of exemption going forwards. I really hope you get to the bottom of what the issue is, as it's very complicated not being able to do a lateral flow test with confidence of accuracy!
Hi Melissa, I'm diagnosed with undifferentiated connective tissue disease (only diagnosed this year, rheumatologist said it could change to an RA or lupus diagnosis). I have tested positive on every lateral flow test I have done since May (twice weekly), every PCR has been negative. I'm thankful to have found someone with a similar experience!
Hi Soph, I am so sorry to hear you are having this problem, but glad you have found me on here! I do have some developments since posting this. The false positives had exclusively come from NHS lateral flow tests provided by Xiamen Biotime Biotechnology. They are the tests we got in the unbranded blue and white boxes. I assume you have used these too? These particular tests always delivered false positives for me.
However, recently we ordered a new batch These are a brand called FlowFlex, which is clearly shown on the outside of the pack. Well, they work for me! They are nose only swabs, so I wasn't holding out hope but it's so far so good. Have you come across those ones yet? If so, how did you get on?
Hi Melissa, yes they're the lateral flow tests that I have been using. Do you know where I can order the flowflex tests from? I've tried all of my local pharmacies who only have the xiamen ones.
Hi Soph, I have heard that pharmacies still have the Xiamen ones. I have been ordering them online: gov.uk/order-coronavirus-ra...
The last three packets have been FlowFlex and I have only had one false positive, which is much better than my 100% track record with the Xiamen ones! Good luck and let me know how you get on.
Hi Melissa, I did a flowflex test today and it's negative. I also did a xiamen one which was positive. Thanks for your help, I'll be sticking to the flowflex ones from now on!
Hi Soph, I am really glad you have found some that work for you. It's such a relief being able to test at home isn't it? I don't know what to do about the Xiamen ones, as I feel I should report the findings but I am not quite sure who to report it to. Have you logged the issue anywhere? Thanks, Melissa
I have had the exact same but I am the opposite and only get false positives with the Flowflex brand just in the nose, the other non-branded (nose and throat) ones are negative for me.
I have had positives with every flowflex so far which is a box of 7, but a negative qPCR.
So confusing. I don't have RA, but was diagnosed with fibromyalgia in 1997 as I suffer with chronic pain. I suspect fibromyalgia is because they haven't found the real cause.
Anyway, thank you for your post as it has given me some clarity.
Hi Sarah, I am really sorry you are going through this too! I think there are more of us than we realise but it's still incredibly difficult to trust these tests and to know what to do about it.
It seems so inconsistent as well. It would make much more sense if we all had the same issue with the same brand of tests, but clearly this isn't the case. Have you spoken to your GP about it? Mine was totally stumped but at least referred the issue to virology at Guys.
I have a really mild cold at the moment, so now wondering if the FlowFLex is picking up a common coronavirus. The cold was what was worrying me as I really didn't want to pass Covid19 on if the PCR was wrong. With getting negatives on the NHS labelled brand though, and reading your post I'm not as concerned now.
The other possibility I thought of is CSF, as I have high intercranial pressure from excess cerebral spinal fluid, so could have a CSF leak in my nose. Maybe that interferes with it, similar to what the kids found out with fruit juice!
Either way it's not very reassuring knowing they're less sensitive than made out. I also have to take 2 tests a week with work, so I hope they don't switch brands. If it carries on in a week or so I'll definitely call the GP.
I reported it to test and trace but they seemed entirely disinterested, I also contacted NRAS who said that they're aware of this but don't have an answer as to why it's happening. I've seen in the recent news that there is now a trend in the south west where several people are getting positive LFD's then negative PCR's, so perhaps they may become more interested and open to the idea that these tests aren't as good as they think.
Honestly, I think Test and Trace are about as useful as a chocolate teapot! I saw in the news what was happening and was wondering the same. I actually have since found out that it's meant to be reported to the Yellow Card scheme, which is where many people report side effects to the vaccine. I had no idea, nor it on any of the packaging for the LFTs (I don't think) but there is also a section on there to report issues with tests: coronavirus-yellowcard.mhra...
Interesting to see what the results of their investigations into this are.
Hi Melissa,My husband has had positive lateral flows since Wednesday (so for 5 days now) - the line is very heavy on each. His PCR came back negative too!
I appreciate this is an old post but I only ever get positive results when I use FlowFlex... on 3 occasions now (each 6 months apart) I have isolated thinking I have covid but get no symptoms just a VERY faint positive line. No other LFT brands detect it. On 2 additional occasions I have definitely had COVID-19 as felt rough and had dark positive lines on other brands of test. Just wondering if you ever found out any further information?
Hello, I though I'd just add my experience. I RF and ccp positive and recently started low dose of methotrexate alongside hydroxy. I had to undergo a hospital recently and had to do a LFT before admission. Unfortunately I came back positive with a very very faint line on flowflex. Repeating this yielded the same result. Had to cancel my procedure and quarantine myself as my family was travelling very shortly. I did daily LFTs which were always faintly positive but getting no worse and a PCR which was negative. So didn't know what to think. I had no symptoms. I changed to the surescreen brand to try and came back negative. I don't know if it's my condition or the medication that might be doing something with the flowflex test. Quite possibly didn't actually have covid. But ruined quite alot of plans. No more flowflex for me I think. There is a limited study that suggested false positives are more likely for some brands of LFT for people with autoimmune conditions. I would suggest trying multiple brands of LFTs if you do test positive especially if it's very very faint.
I felt strange the day after my first covid vaccination years ago and this feeling lasted about 48 hrs only. During that period I did a lateral flow test which was strong positive.PCR negative.I tested positive on lateral flow tests for about 10 weeks after. I also could not understand so carried out the occasional lateral flow test more as an experiment. All were carried out properly following the strict guidelines given. I was taking sulphasalazine but not at the same time as the test. I was given no explanation. I had covid years later with strong covid symptoms and was positive on lateral flow tests for about 3 weeks. I was then taking benepali but denied antivirals.
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Who can still get free lateral flow tests from this Friday?
Off topic - free lateral flow tests for general population 
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