Lateral flow tests have been increasingly in demand over the last few weeks with the rapid spread of the latest Covid-19 variant that is threatening to shut down parts of the economy again.
But, as the lateral flow can be done at home, people are still unsure about the reliability of the test and what to do after a positive result, Wales Online reports.
A London doctor has revealed that a false-positive result could be determined by a faint line.
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Dr Nathan took to his Instagram account @expedition_doctor and shared a picture to 19.3k followers of a lateral flow test with a barely noticeable positive line.
He explained that this “positive” line does not count as a positive test if it emerges after the 30-minute timeframe.
According to Nathan, the line could have been generated by a very mild pollutant, such as food or drinks, rather than coronavirus.
But the A&E doctor advised followers that any line that comes before the end of the 30-minutes interpretation window is a positive test and you must self-isolate and book a PCR.
Nathan wrote: “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.”
He added: “Close contacts of Covid should do daily LFTs for seven days if both asymptomatic and fully vaccinated, or asymptomatic and 18 or under.
“If not a close contact, then you should do a LFT before mixing with people indoors and before visiting someone who is at higher risk of getting seriously ill from Covid.
“Lastly, please remember, if you have symptoms, you should isolate and book a PCR, even with a negative LFT.”
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