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COVID tests - PCR vs lateral flow

Dr Roger Henderson
Reviewed by Roger HendersonReviewed on 29.04.2024 | 3 minutes read

PCR tests (polymerase chain reaction tests) have been used since the start of the pandemic to test for the presence of the COVID-19 (coronavirus) and alert scientists to any new variants. A PCR test needs to be sent off to a laboratory, and results can take one to three days to return.

Rapid lateral flow tests came in a bit later in the pandemic, and can be done at home, with the result quickly available within minutes and they resemble a pregnancy test.

Generally speaking, the lateral flow test is useful for those without symptoms and the PCR test is for those with symptoms. Anecdotally, the PCR test may show positive a few days prior to the lateral flow test.

How have rules changed?

The UK government previously had a policy to test those with symptoms and legally request they isolate for a certain number of days. Testing was used to confirm infection and to release from isolation early if negative.

However, the government’s current strategy is now to learn to live with COVID-19, and has significantly scaled back free testing, preferring instead that the public takes responsibility to isolate themselves if they think they have caught COVID-19, but now without any legal requirement to do so.

You are unable to order PCR tests from the NHS, and you can only order lateral flow tests if you are in certain high-risk groups such as the over-75s or immunosuppressed. Frontline health and social care workers can also order tests.

Taking a lateral flow test with no symptoms

Lateral flow tests are a highly reliable way of testing those without symptoms. They were previously free to order and encouraged by the UK government if you were attending crowded events or to use regularly to attend work or school but the rules have changed. These are now only available for free if you fall into certain vulnerable categories, such as over-75s, over-12s with a weakened immune system, or frontline health and social care workers.

Rapid lateral flow tests are available to buy from pharmacies and other retailers, and people may wish to use these for regular testing if they are mixing outside their household and want the reassurance of knowing they remain COVID free.

So if I can’t get a test, how do I know I’ve got COVID?

From the start of the pandemic, there have been three typical COVID symptoms - a new persistent cough, fever and change to your sense of taste or smell – although multiple other symptoms are linked to this infection.

With most people being fully vaccinated now, and new virus variants emerging, these symptoms are no longer typical of a COVID infection, and the medical authorities have added nine more COVID symptoms: shortness of breath, feeling tired and exhausted, an aching body, a headache, a sore throat, a blocked or runny nose, loss of appetite, diarrhoea and feeling nauseous or being sick.

With these symptoms, you may feel more like curling up under the duvet than meeting friends or going to work, but without access to free testing, these may be an indication that you should avoid others, especially those who are vulnerable.

What about self-isolation?

With the new rule changes, there is no longer a legal requirement to isolate if you’ve tested positive for COVID or have the symptoms and so you don’t need to prove you have a negative lateral flow test after a certain number of days in order to end your isolation.

However, the UK government continues to encourage people to act responsibly to prevent spread of any infection, so if you suspect or know you have COVID, it's advised that you stay at home for at least 5 days and avoid contact with others where possible.

*Information correct on 9 February 2023

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Dr Roger Henderson
Reviewed by Roger Henderson
Reviewed on 29.04.2024
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