There has been a significant increase in lateral flow testing as the Omicron variant continues to spread across the UK.
However there is still confusion over reading the results of the test and what action to take next, Glasgow Live reports.
A doctor has explained on social media how to tell if a faint line on these tests could be a sign of a false-positive result.
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On his Instagram account, @expedition_doctor Nathan shared a picture of a lateral flow test (LFT) with a barely noticeable positive line.
The doctor, based in London, explained that if this “positive” line appears after the 30-minute window in which testers should wait for a result, then it does not count as a positive test.
He explained how the line may have been caused by very weak contaminant, such as food or drinks, rather than covid-19.
Nathan said if any line appears before the end of the interpretation window – which is usually 30 minutes – then this is a positive test and you must self-isolate and book a PCR.
He posted: “If the faintly positive line appears after the time window, the most likely cause is either that there has been some contamination (e.g. food or drink, or some other very weak contaminant that is causing a false positive), or there are just incredibly low levels of the virus.
“If it is the latter, and obviously assuming you are asymptomatic at this point, then you are very unlikely to be a transmission risk anyway and so it is of little significance.
“Therefore, the most sensible next step, in my opinion, is not to isolate unnecessarily (bad for mental health and work etc), and not to book a PCR (makes it harder for people who genuinely need them to get one), but to be extra careful with precautions (social distancing, hand washing and mask wearing), and to continue testing with LFTs as per NHS guidance.”
Nathan said that close contacts of covid should do daily LFTs for seven days if both asymptomatic and fully vaccinated, or asymptomatic and 18 or under
He said those who are not a close contact should do a LFT before mixing with people indoors and before visiting someone who is at higher risk of getting seriously ill from Covid.
The doctor has reminded those who have symptoms to isolate and book a PCR, even with a negative LFT.
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