Lateral Flow Test: What You Need to Know
A lateral flow test looks for certain markers (proteins and hormones) on a sample of fluid, to give a positive or negative result. There are many different types of lateral flow tests - you may be familiar with a home pregnancy test or the quick COVID-19 test, both of which are lateral flow tests.
What can you find here
How does it work?
A lateral flow test for COVID-19 has been developed which detects a protein (known as an antigen) that the body produces while fighting a current COVID-19 infection. The test cannot tell you if you have had COVID-19 in the past. Taking 20 to 30 minutes to get a result, a lateral flow test tends to be much quicker than a COVID-19 PCR test, where the samples must be sent off to a laboratory.
In the beginning, lateral flow tests were thought to be significantly less accurate than PCR but studies have found that when used correctly, they are around 80% effective at detecting any active COVID-19 infection.
A lateral flow test is still the main method used to check for infection in those without symptoms. Around a quarter of people who have COVID-19 don’t get any symptoms and so regular lateral flow testing can help identify these people and prevent the spread of COVID-19. If you have a positive lateral flow test you no longer need to do a confirmatory PCR test.
What happens in the test?
In the UK the testing is done by using a clean sterile swab (a thin plastic stick with a soft end, like a cotton bud) to collect secretions from the inside of your nose and at the back of your throat, near your tonsil area. You need to twirl the swab around for 5 seconds in each area. This can be uncomfortable, make your eyes water or make you gag.
The swab then goes into a pot containing some fluid where you will twist and press the swab against the side to release the secretions into the fluid. If you are doing the test for yourself, you will then put a few drops of this fluid onto the lateral flow device. After waiting a specified number of minutes, you are then able to read the results from your device.
Devices differ, but usually, two lines means a positive result, one line means a negative result (or occasionally an invalid test). Instructions may vary slightly with different testing kits, so remember to always read the instructions and check all the expiry dates.
What if I have a positive COVID-19 lateral flow test?
Regardless of whether you have symptoms or not, if you have a positive lateral flow test you should self-isolate and cannot go to work or mix with anyone else – where possible, you should try to keep yourself separated from your family or other members of your household.
You do not need to do a PCR to confirm the result.
You can end self-isolation after 5 days if you have two negative lateral flow tests on days 5 and 6 and no temperature.
What can you find here