London Daily

Focus on the big picture.
Tuesday, Oct 07, 2025

Rare Blood Clot Risk Higher From Coronavirus Than Vaccine, Says UK Study

Rare Blood Clot Risk Higher From Coronavirus Than Vaccine, Says UK Study

The risk of rare blood clotting following the COVID-19 infection is around 100 times greater than normal, several times higher than it is post-vaccination or following influenza, according to a new University of Oxford study published on Thursday.
The risk of rare blood clotting following the COVID-19 infection is around 100 times greater than normal, several times higher than it is post-vaccination or following influenza, according to a new University of Oxford study published on Thursday.

The research found that the rare blood clotting known as Cerebral Venous Thrombosis (CVT) is more common after COVID-19 than in any of the comparison groups, with 30 per cent of these cases occurring in the under 30s.

Compared to the current COVID-19 vaccines being administered, this risk is between 8-10 times higher, and compared to the baseline, approximately 100 times higher.

The study follows reports of possible links between the Oxford/AstraZeneca vaccine and rare cases of CVT, which are undergoing deeper investigations by the medicines regulators even as the jabs have been ruled as safe and effective.

"There are concerns about possible associations between vaccines and CVT, causing governments and regulators to restrict the use of certain vaccines. Yet, one key question remained unknown: 'What is the risk of CVT following a diagnosis of COVID-19?''," said Paul Harrison, one of study authors as Professor of Psychiatry and Head of the Translational Neurobiology Group at the University of Oxford.

"We've reached two important conclusions. Firstly, COVID-19 markedly increases the risk of CVT, adding to the list of blood clotting problems this infection causes.

"Secondly, the COVID-19 risk is higher than we see with the current vaccines, even for those under 30; something that should be taken into account when considering the balances between risks and benefits for vaccination," he said.

The study authors, led by Professor Harrison and Dr Maxime Taquet from Oxford University's Department of Psychiatry and the NIHR Oxford Health Biomedical Research Centre, counted the number of CVT cases diagnosed in the two weeks following diagnosis of COVID-19, or after the first dose of a vaccine. They then compared these to calculated incidences of CVT following influenza, and the background level in the general population.

"The signals that COVID-19 is linked to CVT, as well as portal vein thrombosis - a clotting disorder of the liver - is clear, and one we should take note of," said Dr Maxime Taquet, also from the Translational Neurobiology Group.

In the study of over 500,000 COVID-19 patients, CVT occurred in 39 in a million patients. In over 480,000 people receiving a COVID-19 mRNA vaccine, such as Pfizer/BioNTech or Moderna, CVT occurred in four in a million, and CVT has been reported to occur in about five in a million people after first dose of the Oxford/AstraZeneca COVID-19 vaccine.

"Compared to the mRNA vaccines, the risk of a CVT from COVID-19 is about 10 times greater. Compared to the AZ-Oxford (Oxford/AstraZeneca) vaccine, the risk of a CVT from COVID-19 is about eight times greater," the findings note.

However, the researchers said that all comparisons must be interpreted cautiously since data is still accruing. An important factor that requires further research is whether COVID-19 and vaccines lead to CVT by the same or different mechanisms. There may also be under-reporting or mis-coding of CVT in medical records, and therefore uncertainty as to the precision of the results, the study authors note.

The findings come as numerous countries have limited use of the Oxford/AstraZeneca vaccine to certain age groups or paused its rollout. Denmark has dropped the jab from its vaccination programme permanently following reports of very rare cases of blood clots.

Earlier this month, the UK''s Medicines and Healthcare products Regulatory Agency (MHRA) said the vaccine is still safe and effective but said that people under-30 will be offered an alternative, where possible, as an additional precaution.

The overall advice, including from the World Health Organisation (WHO), remains in favour of continued vaccinations as the experts concluded that the life-saving benefits of the Oxford/AstraZeneca vaccine continue to outweigh the risks.
Newsletter

Related Articles

0:00
0:00
Close
France: Less Than a Month After His Appointment, the New French Prime Minister Resigns
Hungarian Prime Minister Viktor Orbán stated that Hungary will not adopt the euro because the European Union is falling apart.
Sarah Mullally Becomes First Woman Appointed Archbishop of Canterbury
Mayor in western Germany in intensive care after stabbing
Australian government pays Deloitte nearly half a million dollars for a report built on fabricated quotes, fake citations, and AI-generated nonsense.
US Prosecutors Gained Legal Approval to Hack Telegram Servers
Macron Faces Intensifying Pressure to Resign or Trigger New Elections Amid France’s Political Turmoil
Standard Chartered Names Roberto Hoornweg as Sole Head of Corporate & Investment Banking
UK Asylum Housing Firm Faces Backlash Over £187 Million Profits and Poor Living Conditions
UK Police Crack Major Gang in Smuggling of up to 40,000 Stolen Phones to China
BYD’s UK Sales Soar Nearly Nine-Fold, Making Britain Its Biggest Market Outside China
Trump Proposes Farm Bailout from Tariff Revenues Amid Backlash from Other Industries
FIFA Accuses Malaysia of Forging Citizenship Documents, Suspends Seven Footballers
Latvia to Bar Tourist and Occasional Buses to Russia and Belarus Until 2026
A Dollar Coin Featuring Trump’s Portrait Expected to Be Issued Next Year
Australia Orders X to Block Murder Videos, Citing Online Safety and Public Exposure
Three Scientists Awarded Nobel Prize in Medicine for Discovery of Immune Self-Tolerance Mechanism
OpenAI and AMD Forge Landmark AI-Chip Alliance with Equity Option
Munich Airport Reopens After Second Drone Shutdown
France Names New Government Amid Political Crisis
Trump Stands Firm in Shutdown Showdown and Declares War on Drug Cartels — Turning Crisis into Opportunity
Surge of U.S. Billionaires Transforms London’s Peninsula Apartments into Ultra-Luxury Stronghold
Pro Europe and Anti-War Babiš Poised to Return to Power After Czech Parliamentary Vote
Jeff Bezos Calls AI Surge a ‘Good’ Bubble, Urges Focus on Lasting Innovation
Japan’s Ruling Party Chooses Sanae Takaichi, Clearing Path to First Female Prime Minister
Sean ‘Diddy’ Combs Sentenced to Fifty Months in Prison Following Prostitution Conviction
Taylor Swift’s ‘Showgirl’ Launch Extends Billion-Dollar Empire
Trump Administration Launches “TrumpRx” Plan to Enable Direct Drug Sales at Deep Discounts
Trump Announces Intention to Impose 100 Percent Tariff on Foreign-Made Films
Altman Says GPT-5 Already Outpaces Him, Warns AI Could Automate 40% of Work
Singapore and Hong Kong Vie to Dominate Asia’s Rising Gold Trade
Trump Organization Teams with Saudi Developer on $1 Billion Trump Plaza in Jeddah
Manhattan Sees Surge in Office-to-Housing Conversions, Highest Since 2008
Switzerland and U.S. Issue Joint Assurance Against Currency Manipulation
Electronic Arts to Be Taken Private in Historic $55 Billion Buyout
Thomas Jacob Sanford Named as Suspect in Deadly Michigan Church Shooting and Arson
Russian Research Vessel 'Yantar' Tracked Mapping Europe’s Subsea Cables, Raising Security Alarms
New York Man Arrested After On-Air Confession to 2017 Parents’ Murders
U.S. Defense Chief Orders Sudden Summit of Hundreds of Generals and Admirals
Global Cruise Industry Posts Dramatic Comeback with 34.6 Million Passengers in 2024
Trump Claims FBI Planted 274 Agents at Capitol Riot, Citing Unverified Reports
India: Internet Suspended in Bareilly Amid Communal Clashes Between Muslims and Hindus
Supreme Court Extends Freeze on Nearly $5 Billion in U.S. Foreign Aid at Trump’s Request
Archaeologists Recover Statues and Temples from 2,000-Year-Old Sunken City off Alexandria
China Deploys 2,000 Workers to Spain to Build Major EV Battery Factory, Raising European Dependence
Speed Takes Over: How Drive-Through Coffee Chains Are Rewriting U.S. Coffee Culture
U.S. Demands Brussels Scrutinize Digital Rules to Prevent Bias Against American Tech
Ringo Starr Champions Enduring Beatles Legacy While Debuting Las Vegas Art Show
Private Equity’s Fundraising Surge Triggers Concern of European Market Shake-Out
Colombian President Petro Vows to Mobilize Volunteers for Gaza and Joins List of Fighters
×