Delta variant Covid symptoms - do lateral flow tests detect the Delta variant?

Woman sneezing with new symptoms of Covid-19
(Image credit: Getty Images/Westend61)

As the Delta variant is now dominant in the UK, experts are warning that Covid symptoms to look out for have changed.

Since the very beginning of the pandemic (opens in new tab), we've been told to look out of three symptoms which indicate Covid-19 infection: a high temperature, continuous cough and a loss of taste and/or smell. The emphasis has been on washing hands, wearing a mask (opens in new tab) and self-isolating at first sign of a splutter or fever. Even as other variants emerged last year, experts maintained warnings about these three main symptoms.

However the new Delta variant has thrown this all into question. Following recent data collection by the app-based Zoe symptom study (opens in new tab), experts are now warning people to be aware of totally different symptoms that have proven links to the new variant.

What are the new Delta variant Covid symptoms?

The three new Covid symptoms to look out for are: 

  • Headaches 
  • Sore throat
  • Runny nose

These are the most common symptoms of the Delta variant, researchers from the Zoe Covid symptom study have said. Instead of a specific set of more unusual symptoms, they suggest that the Delta variant feels more like a “bad cold”.

It's for this reason that people are asking whether you should go into work with a cold during the Covid-19 pandemic (opens in new tab). Since October this year, many people have returned to offices - despite the risk of infection.

Tim Spector, a professor of genetic epidemiology at King’s College London is leading the study. He said, “Covid is acting differently now, it’s more like a bad cold.

“People might think they’ve just got some sort of seasonal cold, and they still go out to parties. We think this is fuelling a lot of the problem. So, what’s really important to realise is that since the start of May, we’ve been looking at the top symptoms in all the app users, and they’re not the same as they were. So, the number one symptom is headache, followed by sore throat, runny nose and fever.” 

Whereas previously a continuous cough was one of the most common symptoms, it’s now only the fifth most-common. A loss of smell is not in the top 10 list of common Covid symptoms experts have linked to the Delta variant. 

The warning about these new Covid symptoms comes as the Delta variant is now dominant in the UK. The most up-to-date data from Public Health England (PHE) shows that the variant is responsible for up to 95% of all new cases (opens in new tab) of the virus in England, since it's significantly more transmissible (by up to 64%) than the other variants. It also appears to double the risk of hospitalisation (opens in new tab) as well.  

The new variant is also slightly resistant to the Pfizer, Moderna and Oxford vaccines - particularly after only one dose. PHE research (opens in new tab) shows that the vaccines, however, do offer all round good protection after both doses. This is one of the reasons that many people have been eager to get their second Covid vaccine dose early (opens in new tab).

As Professor Spector said, “I think the message here is that if you’re young and getting milder symptoms any way, it might just feel like a bad cold or some funny stay at home and do get a test.” 

Do lateral flow tests work on Delta variant?

Lateral flow tests do work to detect the Delta variant, experts have confirmed.

Professor Tim Spector has urged anyone feeling unwell to stay at home. And importantly, use a lateral flow test (opens in new tab) and follow up with a PCR test if they get a positive result.

"The number one symptom is headache, followed by runny nose, sore throat and fever. Not the old classic symptoms. We don’t see loss of smell in the top ten any more. This variant seems to be working slightly differently," he said.

Person taking lateral flow test to combat the spread of the new Delta variant

Lateral flow come with instructions on how to use them (Credit: Getty).

Lateral flow tests will work on the Delta variant, an article in the British Medical Journal (opens in new tab) explains, as the kits detect viral proteins (antigens) from the virus in respiratory samples. The antigens in the sample bind to specific antibodies attached to the paper strip on the test. This, in turn, creates the purple lines that indicate a positive result.

However, it's important to note that lateral flow tests rely on the person having a high viral load. Those who have contracted Covid-19 but are asymptomatic (opens in new tab) with the virus tend to have a lower viral load (opens in new tab) than those with symptoms, meaning the test could be less effective. This is why self-isolating if you have come into contact with a Covid-positive person is important.

Following a high spike in the number of people contracting Covid-19, the government have put out further guidance on when to use each of the tests.

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To take a lateral flow test, take a swab from the back of your throat and your nose. Drop the swab into the liquid provided. Then add the solution carefully to the test strip and wait for between 20 to 30 minutes for your result. If positive, you should follow up with a PCR test. These are more accurate than lateral flow tests at diagnosing infection.

Anyone can get two free lateral flow tests per week in England, without displaying any symptoms. People can order them online (opens in new tab), call 119 or collect from local test centres and pharmacies.

The emergence of the new Delta variant is the main reason why some countries are requiring UK travellers to have proof of their Covid vaccines (opens in new tab) before they can enter. Many are also allowing travellers into the country with a negative PCR test. But there are some that are only allowing fully vaccinated visitors to enter without a quarantine period.

Is the Delta variant more deadly?

Early evidence suggests that the Delta variant may cause more serious illness than other variants.

PHE have already confirmed that the new variant may increase the risk of hospitalisation. Their analysis (opens in new tab) of over 38,000 Covid-19 cases found that those who contracted the Delta variant of Covid-19 were 2.61 times more likely to be admitted to hospital than those with the Alpha variant, which was dominant in the UK last year.

However, PHE has also confirmed that hospital attendances and admissions "are predominantly in unvaccinated individuals". Just one dose of the Pfizer vaccine (opens in new tab) is 94% effective at preventing hospital admission as a result of the Delta variant, according to the same analysis by PHE. This increases to 96% after two doses. The Oxford vaccine (opens in new tab) is also effective at preventing hospital admissions - by 71% after one dose and 92% after two doses.

This suggests that the new Covid variant is most deadly to those who haven't had any shots of the vaccine.

The labelling of this new variant as a 'variant of concern' led to the government to delay the end of lockdown (opens in new tab) until July 19. Previously. The lockdown roadmap (opens in new tab) gave an original end date of June 21 for all lockdown restrictions. However, Prime Minister Boris Johnson said that the "sensible" course of action would be to "wait just a little longer" to ease restrictions.

By delaying the end of lockdown for one month, the government hoped to significantly increase the number of people who have both Covid-19 jabs and reduce the chance of having to go into a circuit breaker lockdown (opens in new tab) again in the future. 

“Vaccination greatly reduces transmission and two doses provide a very high degree of protection against serious illness and death. But there are still millions of younger adults who have not had either vaccine. Sadly a proportion of the elderly and vulnerable may still succumb even if they have had two jabs.

“And that is why we are so concerned by the Delta variant that is now spreading faster than the third wave predicted in the February roadmap,” the PM said. 

By Monday 19th July we will aim to have double jabbed around two thirds of the adult population including everyone over 50, all the vulnerable, all the frontline health and care workers and everyone over 40 who received their first dose by mid-May. And to do this we will now accelerate the 2nd jabs for those over 40. Just as we did for the vulnerable groups – so they get maximum protection as fast as possible.” 

It's because of the transmissibility of the Delta variant that some people are eligible for a third vaccine. GP surgeries and local pharmacies will be in contact with those vulnerable to Covid to book a Covid booster jab (opens in new tab) before the end of September.

As of July 19, 54% of all people living in the UK have received their second dose of the vaccine. Over 80 million people have had their first dose.

Grace Walsh
Features Writer

Grace Walsh is a Features Writer for, covering breaking news health stories during the Covid-19 pandemic as well as lifestyle and entertainment topics.  She has worked in media since graduating from the University of Warwick in 2019 with a degree in Classical Civilisation and a year spent abroad in Italy. It was here that Grace caught the bug for journalism, after becoming involved in the university’s student newspaper and radio station.