How does a lateral flow test work? Government’s new rapid Covid tests explained

Free rapid testing is being rolled out to everyone in England and Scotland to help control the emergence of new Covid-19 variants

Lateral flow Covid-19 tests are being offered to everyone in England and Scotland, as part of plans to control the spread of coronavirus.

The tests can return results within just 30 minutes and will be available for free to be taken twice weekly.

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The widespread rollout comes ahead of more lockdown restrictions being eased across the UK, in the hope it will help to identify and control the emergence of new Covid-19 variants.

If the test shows one line next to the letter ‘C’ it is negative (Photot: Getty Images)

Here’s everything you need about how the tests work and how to take them.

What are lateral flow tests?

Lateral flow testing is a rapid way of testing people who do not have any symptoms of Covid-19, but could still unknowingly be spreading the virus.

Around one in three people with coronavirus do not display any symptoms, so rolling out this method of testing will help to identify positive cases earlier and break hidden chains of transmission.

The tests provide quick results in around 30 minutes and can be used in a wide range of settings, making them ideal for widespread rollout across the country.

How does the test work?

Lateral flow is an established technology which is adapted to detect proteins (antigens) that are present when a person has Covid-19.

The best known example of a lateral flow test is the home pregnancy test kit.

The test is a hand-held device which has an absorbent pad at one end and a reading window at the other, with a strip of test paper inside that changes colour in the presence of Covid-19 proteins.

If the test shows one line next to the letter ‘C’, this means that the test is negative.

If the test displays two lines, one next to the letter ‘C’ and the letter ‘T’, this is a positive result, even if the lines are faint.

A void test will show no lines, or one line next to the letter ‘T’. In this case, you will need to retake the test with a fresh kit.

If you get a positive result, you must self-isolate immediately to prevent any further transmission.

A negative result means that an active coronavirus infection was not detected at the time the test was taken, although this does not necessarily guarantee you do not have Covid-19.

People who receive a negative test should continue to follow lockdown rules, including social distancing, regular hand washing, and wearing face coverings where required.

How do I take the test?

Taking a lateral flow test involves taking a sample from the back of the throat near the tonsils and from the nose, using a swab.

This swab is then dipped into an extraction solution and dripped on to the device’s paper pad which produces a reaction to provide a result.

This result will be visible on the device in 30 minutes after the sample is applied. Unlike a PCR test, the swab does not need to be sent to a lab to get the results.

How to order one

From Friday (9 April), people in England will be able to get a test via a home ordering service, workplace, or school testing programme, or by collecting one at a local test site.

A new “pharmacy collect” service is also being launched to provide additional access to regular testing.

Those aged 18 and over without coronavirus symptoms will be able to use the service by visiting a participating local pharmacy and collect a box of seven rapid tests to use twice a week at home.

To find a rapid lateral flow test site in your area, or a local pharmacy to collect a test to do at home, enter your postcode on the government website.

Scotland’s First Minister Nicola Sturgeon has announced that a similar scheme will be rolled out in Scotland, with the Scottish government due to provide more detail ‘later this week’.

Wales will not be following the testing policy, as much of the population have already been receiving regular tests.

Lateral flow testing is currently being offered to people who don’t have symptoms, in a range of different settings, including regular testing of NHS and social care staff, as well as in universities, schools, care homes and other workplaces.

In Northern Ireland, you can only book a Covid-19 if you have symptoms of the virus. This can be done online, at a drive or walk through test site, by ordering a postal self-test kit online, or by calling the free phone number 119.

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