Beautiful Virgin Islands

Monday, Aug 04, 2025

Can you trust a negative lateral flow Covid test?

Can you trust a negative lateral flow Covid test?

Analysis: with cold symptoms, it is better to wait for a PCR result rather than risk spreading the virus

You wake up with a pounding head, sore throat and runny nose: you reach for one of those lateral flow tests (LFT) you’ve got stashed away, just to check it is not Covid. If it returns a single red line (negative), then most people will pop a couple of paracetamol and go about business as normal – particularly if you’ve been double-jabbed. It probably is just a cold, after all.

Yet, the emergence of Omicron has thrown a spanner in the works. According to the latest data, just one month after your second Pfizer or AstraZeneca jab, the ability of antibodies to neutralise Omicron is 30 times lower than if you were infected with the Delta variant – reinforcing the message that double-vaccination is no guarantee against infection.

The study follows recent UK Health Security Agency (UKHSA) data, suggesting those who have been double-jabbed with the AstraZeneca vaccine have about 10% protection against symptomatic infection with Omicron six months after their second jab, compared with 40% protection against the Delta variant.

So, if you’re relying on an LFT to guide whether or not it is safe for you to leave the house, the chances of you being infected, despite being vaccinated, just got higher.

The UK government has always stressed that people with Covid symptoms should seek a PCR test, rather than relying on a LFT. Yet, it still defines these symptoms as a high temperature, new, continuous cough and/or a loss or change to your sense of smell or taste – despite widespread evidence that headaches, fatigue, a sore throat or runny nose are also common Covid symptoms.

Also, whereas getting a PCR test involves all the trouble of going online, booking a test, either going to a test centre or waiting to have a test delivered, and then waiting a day or two to receive the test results, a LFT delivers a result within minutes.

OK, we know they’re not as accurate as PCR tests, but they’re pretty accurate – especially if you’ve been vaccinated and/or had Covid recently – right?

It is true that lateral flow tests return an accurate result more often than not: a Cochrane review of 64 studies found that they correctly identify 72% of infected people who have symptoms, and 78% within the first week of becoming ill. Further, the Department of Health and Social Care (DHSC) claims that the Innova LFT detects more than 95% of individuals with highest viral loads – those who are most likely to spread the virus.


Yet, the Medicines and Healthcare products Regulatory Agency (MHRA), has long-expressed concerns that people may be falsely reassured if they test negative on an LFT: it authorised their use as a “red light” – to find infectious people and order them to self-isolate – rather than providing a “green light” to those who test negative.

There are several reasons why your negative LFT might be wrong: you might not be swabbing thoroughly enough, or you could have a dodgy test kit. Of course, these issues can also undermine the accuracy of PCR tests – remember the Wolverhampton testing lab fiasco, that saw up to 43,000 people falsely reassured that they didn’t have Covid, despite many of them testing positive on a LFT? Yet, PCR tests are more sensitive than LFT, meaning they’re more likely to register some virus, even if your swabbing technique isn’t much cop. They’re also much more likely to return a positive result during the early stages of infection, when there’s less virus available to detect.

Studies have suggested that PCR tests start to pick up Sars-CoV-2 roughly 1-3 days before the onset of symptoms (assuming the person is symptomatic) – similar to when people start to become infectious. However, virus levels don’t peak until between the first and fifth day of symptoms, on average. So, if you’re swabbing as soon as you start to feel unwell, that might be too soon to return a positive LFT.

These tests have thankfully freed us from the confines for that first lockdown, when the advice was to self-isolate based on symptoms alone. But with infection levels sky high, Covid symptoms that too often resemble the common cold, and waning immunity from vaccines, perhaps it’s time to reinstate a degree of caution and stay home if we feel unwell – at least until we’ve done a PCR test, or had several days of negative LFTs. Who wants someone else’s cold, anyway?

Newsletter

Related Articles

Beautiful Virgin Islands
0:00
0:00
Close
OpenAI’s Bold Bet: Teaching AI to Think, Not Just Chat
Tesla Seeks Shareholder Approval for $29 Billion Compensation Package for Elon Musk
Nvidia is cutting prices on its RTX 50-series graphics cards after sales slowed and inventories piled up
Ghislaine Maxwell Transferred to Minimum-Security Prison Amid Ongoing DOJ Discussions
U.S. Tariffs Surge to Highest Levels in Nearly a Century Under Second Trump Term
Matt Taibbi Slams Media for Role in Russiagate Narrative
Pilots Call for Mental Health Support Without Stigma
All Five Trapped Miners Found Dead After El Teniente Mine Collapse
Ong Beng Seng Pleads Guilty in Corruption Case Linked to Former Singapore Transport Minister
BP’s Largest Oil and Gas Find in 25 Years Uncovered Offshore Brazil
Italy Fines Shein One Million Euros for Misleading Sustainability Claims
JPMorgan and Coinbase Unveil Partnership to Let Chase Cardholders Buy Crypto Directly
Declassified Annex Links Soros‑Affiliated Officials and Clinton Campaign to ‘Russiagate’ Narrative
UK's Online Safety Law: A Front for Censorship
Nationwide Protests Erupt in Brazil Demanding Presidential Resignation
Parents Abandon Child at Barcelona Airport Over Passport Issue
Mystery Surrounds Death of Brazilian Woman with iPhones Glued to Her Body
Bus Driver Discovers Toddler Hidden in Suitcase in New Zealand
Switzerland Celebrates 734 Years of Independence Amid Global Changes
U.S. Opens Official Investigation into Former Trump Prosecutor Jack Smith
Leaked audio of Canada's new PM Mark Carney admitting the truth about the Net Zero agenda: "We're gonna make a lot of money off of this."
China Enforces Comprehensive Ban on Cryptocurrency Activities
Absolutely 100% Realistic EVO Series Doll by EXDOLL (Chinese Company) used mainly for carnal purposes
World Economic Forum founder Klaus Schwab: "In this new world, we must accept... total transparency. You have to get used to it. You have to behave accordingly. But if you have nothing to hide, you shouldn't be afraid."
Meet Mufti Hamid Patel, head of Office for Standards in Education in Pakistan
George Soros tells the World Economic Forum: "President Trump is a con man and the ultimate narcissist, who wants the world to revolve around him."
Hamas are STARVING the hostages.
Decline in Tourism in Majorca Amidst Ongoing Anti-Tourism Protests
British Tourist Dies Following Hair Transplant in Turkey, Police Investigate
Poland Begins Excavation at Dziemiany After New Clue to World War II‑Era Nazi Treasure
WhatsApp Users Targeted in New Scam Involving Account Takeovers
Trump Threatens Canada with Tariffs Over Palestinian State Recognition
Trump Deploys Nuclear Submarines After Threats from Former Russian President Medvedev
Trump Sues Murdoch in “Heavyweight Bout”: Lawsuit Over Alleged Epstein Letter Sets Stage for Courtroom Showdown
Germany Enters Fiscal Crisis as Cabinet Approves €174 Billion in New Debt
Trump Administration Finalizes Broad Tariff Increases on Global Trade Partners
J.K. Rowling Limits Public Engagements Citing Safety Fears
JD.com Launches €2.2 Billion Bid for German Electronics Retailer Ceconomy
Azerbaijan Proceeds with Plan to Legalise Casinos on Artificial Islands
Former Judge Charged After Drunk Driving Crash Kills Comedian in Brazil
Jeff Bezos hasn’t paid a dollar in taxes for decades. He makes billions and pays $0 in taxes, LEGALLY
China Increases Use of Exit Bans Amid Rising U.S. Tensions
IMF Upgrades Global Growth Forecast as Weaker Dollar Supports Outlook
Procter & Gamble to Raise U.S. Prices to Offset One‑Billion‑Dollar Tariff Cost
House Republicans Move to Defund OECD Over Global Tax Dispute
Botswana Seeks Controlling Stake in De Beers as Anglo American Prepares Exit
Trump Administration Proposes Repeal of Obama‑Era Endangerment Finding, Dismantling Regulatory Basis for CO₂ Emissions Limits
France Opens Criminal Investigation into X Over Algorithm Manipulation Allegations
A family has been arrested in the UK for displaying the British flag
Mel Gibson refuses to work with Robert De Niro, saying, "Keep that woke clown away from me."
×