Lateral Flow Test: What You Need to Know

COVID-19 tests are available for purchase at pharmacies, retail stores, and online. Free or low-cost testing may also be available through local health departments or community health centers. Some insurance plans may cover testing costs.

At-home rapid antigen tests provide results within minutes. PCR tests, which are generally more sensitive, may be available through healthcare providers or testing facilities. If you have COVID-19 symptoms but receive a negative result on an at-home antigen test, repeat the test 48 hours later, following FDA recommendations.

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.

At the start of the COVID pandemic, lateral flow tests were thought to be significantly less accurate than PCR tests, but studies have found that when used correctly, they are around 80% effective at detecting any active COVID-19 infection.

Around a quarter of people who have COVID-19 don’t get any symptoms, so many people felt reassured with regular testing or if visiting elderly or vulnerable relatives or meeting lots of people.

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. You need to twirl the swab around for 5 seconds in each nostril. This can be uncomfortable and make your eyes water.

The swab then goes into a test tube 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 label and check the expiration date.

If you have COVID-19 symptoms, the CDC recommends staying home and away from others until your symptoms have been improving for at least 24 hours and you have been fever-free for at least 24 hours without taking fever-reducing medication. After returning to normal activities, take additional precautions for the next 5 days, such as wearing a well-fitting mask, practicing good hygiene, and avoiding close contact with others. If you test positive but have no symptoms, take these additional precautions for 5 days. Your employer may have specific policies about reporting illness and returning to work.