What are the pink lines on your lateral flow test and what do they mean?

WE’VE all gotten used to waiting over a lateral flow test in anticipation of a singular red line.

But what does it mean when you get a pink or very faint line, and does it signal you are carrying Covid?

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The kits have been crucial in the fight against Covid, allowing people to navigate their lives safely.

If you get a positive result, it sadly means your social plans are off – you are carrying the virus and can pass it to someone else.

The home-kits are not as accurate as PCR tests, which have to be sent off to a lab.

However, the Government credits them for finding Covid carriers who are not showing symptoms, and giving results on the spot.

Here we explain how the tests work, and what all results mean…

What do the results mean?

Negative result: one line next to C shows the test is negative.

Void: no lines, or one line next to T, means the test is void. You will need to re-take with a fresh test kit.

Positive result: Two lines, one next to C and one next to T, even faint lines, shows the test is positive. 

How do lateral flow tests work?

Covid lateral flow tests, or “antigen tests”, work in the same way as pregnancy tests. They use the same technology, which has been around for decades.

The tests detect proteins (antigens) that are present in throat and swab samples, in this case, Covid proteins.

When the sample from the nose or throat is mixed with the buffer solution (the liquid provided in the test kit), the antigens are released into the liquid.

They move along the strip and are captured by antibodies, which are programmed to recognise Covid.

When these antibody and Covid molecules reach the testing site, labelled “T”, a change in colour occurs. Usually a deep red or purpley colour is shown.

Some antibodies are also captured at the “C” site. This creates a positive result.

If there are no Covid antigens present, the antibodies keep moving up the test until they are caught by the “C” site. 

What does a faint or pink line mean?

As the Government explains “even faint lines show the test is positive”.

It adds: “Result lines may appear smudged or faint, but they are still valid results and must be reported.”

A faint or pink positive line could mean that there were not enough viral particles on your sample.

This could either be due to how much sample you collected, or that you are early (or late) in your infection.

Abingdon Health, a British company that makes lateral flow tests, says “the density of the line will vary depending on the quantity of the target present”.

A positive result must be reported to the NHS via this website.

If you get a positive result, you must self-isolate immediately. If you also have symptoms of the virus, you must book a PCR test.

Is this always the case?

London-based A&E doctor Nathan explained that, if a faint pink line appears in the 30 minutes after your test, this means you have Covid.

He told The Sun: “Any positive line within 30 minutes, even if it is so faint that it is barely visible, equals a positive result. 

“However, if a faint line appears after 30 minutes, this can be ignored.”

But if you have symptoms, regardless of the lateral flow test result, you should isolate and book a PCR test.