Lateral Flow Test

What is a lateral flow test?

A lateral flow test (LFT), also known as a rapid flow test, is a swab test to identify whether you are carrying the COVID-19 virus. Lateral flow tests will take a sample from your nose or throat, which is dipped into a solution. The sample is then dripped onto the test cassette, which can identify whether you are carrying COVID-19 within 15 minutes.  

Interpreting lateral flow test results

You should wait 15 minutes before interpreting the results. If you are positive, two lines will appear. The second line often appears 5-10 minutes after the first line.

Positive Lateral flow test

A positive lateral flow result is indicated by 2 lines appearing on the test cassette.

False positive results

A false positive result is highly unlikely. Research has shown LFTs to rule out COVID in 99.5% of people with symptoms, and 98.9% of people without symptoms. So if you have tested positive, it Is highly likely that you are carrying the virus.

Negative lateral flow test

A negative lateral flow test is indicated by 1 line on the top half of the cassette.

False negative results

It is possible to get a false negative LFT results. Rapid testing identifies antigens, which are highest in your body when the virus is most active. If the virus is not at its peak level in your body, you are more likely to get a false negative. Lateral flow tests are likely to be more than 90% effective in detecting COVID in those who are most infectious when testing, and around 80% effective at detecting COVID at any level. Testing will also depend on the quality of sample.

detecting COVID at any level. Testing will also depend on the quality of sample.

What if I have a faint line on my test?

If you have 2 lines on your test, this indicates a positive test. It does not matter how faint or prominent the line is.

What is the difference between the government and NHS lateral flow tests and your rapid test kits?

There is no difference between our test kits, and the government test kits. We use the same brand of tests as the government (Flowflex).

Are your tests approved by the UK government?

We only use government approved test kits, and purchase from authorized wholesalers who also supply the UK government. You can see the registration of the test kits we provide here.

Can I register my lateral flow test online?

We offer private testing, so these kits cannot be registered on the NHS website. Although the kits are identical and sourced from the same suppliers, if you are required to register your kit online, you will need to order a rapid flow test from the UK government website.

What is the accuracy of these tests?

Accuracy – 98.8%

Accuracy is the ability of the test to correctly differentiate between a positive and negative case. Essentially, it is the reliability of the test.

Sensitivity – 97.1%

Sensitivity evaluates the ability of the test in detecting a positive case

Specificity – 99.5%

Specificity estimates how likely negative cases can be correctly ruled out

What if my lateral flow test is negative but my PCR is positive?

If you have a negative lateral flow but a positive PCR test, you should isolate for 10 days.

Can I use a lateral flow test if I have symptoms of COVID-19?

Current guidelines state that rapid test kits are for use with people who do not have symptoms. If you are experiencing symptoms of COVID-19, you should book a PCR test.