If you live in London, the chances are by now, you currently have or know someone who has tested positive for Covid-19 in the last few weeks.
The first port of call if you’ve been exposed to someone who has Covid is to test with lateral flows tests (LFTs).
As we approach Christmas and we all want to keep both ourselves and others safe, lateral flows before meeting anyone, are key.
But with some mixed reports about lateral flow tests consistently showing false negatives, how accurate are they? And are they as good at picking up Omicron? Here are some key questions answered.
What is the difference between lateral flow tests and PCR tests?
Lateral flow tests provide results and tell people in 30 minutes if they have coronavirus by detecting proteins from the virus in the nose and throat samples. Scientists have mixed views on their accuracy.
PCR tests are, however, extremely accurate but take up to three days for results to come through. They detect the genetic material from a specific organism, specifically coronavirus, and are the best way to test if you have a current infection.
Lateral flow tests are designed to be taken if you don’t have any symptoms of coronavirus. As soon as you start showing any symptoms, you need to book a PCR test to get official results, all the while isolating.
Current advice states that if you test positive on a lateral flow you should follow up with a PCR test.
How accurate are they?
There are mixed opinions on lateral flow tests.
The UKHSA maintains they are a "vital tool" for uncovering hidden infections. But some scientists say they give people a false sense of security .
They are faster and cheaper than PCR tests - but may be less accurate.
One study by the Queen Mary University of London published in July found that lateral flow tests detected more than 95 per cent of the cases found by PCR and correctly identified 89 per cent of cases as negative.
But other studies suggest LFTs pick up just 58 per cent of asymptomatic cases.
In March 2021, the Royal College of Pathologists said positive results by LFTs should be confirmed by PCR tests and people should self-isolate before they receive their PCR result.
It can be too soon for a lateral flow test to pick up an infection.
This is because they can be less sensitive than PCR tests and require a higher viral load to record a positive result.
Because of this, it’s possible to get a false negative from a lateral flow test.
They often only identify people during their most infectious period (people are infectious two to three days before symptoms start to show and are most contagious in the first 10 days of catching the virus).
Therefore. the best way to use lateral flow tests effectively is to ensure you’re testing often and especially if you’re planning some meet ups with friends and family over the festive period.
Can they detect Omicron?
Last week, the Health Security Agency (HSA) said lateral flow tests are as likely to detect Omicron as other variants of coronavirus.
You, as the tester, won't of course know which strain you have got when doing the test.
PCR tests are still considered to be the most accurate tests when diagnosing coronavirus but should only be used by people who are showing symptoms.
How can you get hold of lateral flow tests?
The NHS has a searching tool which allows people to find their nearest pharmacies which have tests available to collect. It is: www.maps.test-and-trace.nhs.uk.
Alternatively, you can order a pack from Gov.uk to be delivered to your home. One pack can be ordered per day.
They can also be collected from community collection points or you can visit a testing point near you.
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