Saudi Press

Saudi Arabia and the world
Saturday, Jun 21, 2025

Why are COVID vaccines linked to blood clots? Scientists have answers

Why are COVID vaccines linked to blood clots? Scientists have answers

A group of scientists in Germany claims they have cracked the code as to why AstraZeneca and Johnson & Johnson vaccines are causing blood clots.

Rare fatal blood clots linked to the COVID-19 vaccines AstraZeneca and Johnson & Johnson have caused major concerns, but a group of scientists in Germany claims they have cracked the code as to why this is happening.

The researchers suggest vaccines that put adenovirus vectors - the cold viruses used to insert the spike protein of COVID-19 into the nucleus of the cell - into the body can, in some people, cause bits of coronavirus proteins to enter the nucleus and break up.

The fragments then exit into the bloodstream and can cause clotting. The rare clumps in the blood can then become serious if the clots approach vital organs.

The scientists wrote in a pre-print study, which has not undergone peer review, that the vaccine is delivered to the nucleus of the cell rather than to the fluid around it that acts as a protein factory.

"The adenovirus life cycle includes the infection of cells … entry of the adenoviral DNA into the nucleus, and subsequently gene transcription by the host transcription machinery," the researchers said.

"And exactly here lies the problem: the viral piece of DNA … is not optimised to be transcribed inside of the nucleus".

The Pfizer/BioNTech and Moderna are mRNA vaccines that do not use this system and there have been no cases reported of blood clots with these doses.

But there is a way for the vaccine's manufacturers to eliminate the risks, the scientists claim.

Professor Rolf Marschalek, a professor at Goethe University in Frankfurt who was a part of the study, told the Financial Times the vaccines can be redesigned. He also told the newspaper Johnson & Johnson is in contact with him.

Why do the vaccines affect younger people?


The study suggests that elderly people use drugs that thin blood more often, or even on a daily basis, which could decrease the risk of blood clots.

The researchers also suggested older immune systems display more immune senescence -the progressive decline in immune function with increasing age - which means young peple exhibit stronger immune reactions than elderly people, and women even stronger than men.

A health worker prepares a dose of the AstraZeneca/Oxford vaccine at a coronavirus vaccination centre at the Wanda Metropolitano stadium in Madrid


"All this would imply a higher incidence in young women when compared to men or elderly people," the study said.

The Oxford-AstraZeneca and Johnson & Johnson jabs in particular have been linked to rare deadly blood clotting disorders, especially for women under the age of 60.

What are the vaccine rules in Europe?


The European Medicines Agency (EMA) said in April there was a "possible link" between the AstraZeneca vaccine and "very rare cases of unusual blood clots with low blood platelets".

The agency said it received reports of 169 cases of the rare brain blood clot by early April, after 34 million doses had been administered in the European Economic Area (EEA).

But the EMA stresses the benefits of being vaccinated against COVID-19 outweigh the risks of developing blood clots.

Meanwhile, the United Kingdom has reported 309 clots and 56 deaths out of the 33 million vaccines administered with AstraZeneca. And the Johnson & Johnson vaccine has been linked to 28 cases of blood clots in the United States.

As a consequence, some European countries temporarily halted these vaccines but have now set age limits. However, they have failed to reach a consensus on a common approach to administering them.

In Italy, it is recommended the AstraZeneca vaccine is administered to those over the age of 60, for France over the age of 55 and the UK advises it is not used on those under the age of 30.

Newsletter

Related Articles

Saudi Press
0:00
0:00
Close
Israel Confirms Assassination of Quds Force Commander in Tehran
16 Billion Login Credentials Leaked in Unprecedented Cybersecurity Breach
Senate hearing on who was 'really running' Biden White House kicks off
G7 Leaders Fail to Reach Consensus on Key Global Issues
Mass exodus in Tehran as millions try to flee following Trump’s evacuation order
Iranian Military Officers Reportedly Seek Contact with Reza Pahlavi, Signal Intent to Defect
Vietnam Emerges as Luxury Yacht Destination for Ultra‑Rich
China's Iranian Oil Imports Face Disruption Amid Escalating Middle East Tensions
Trump Demands Iran's Unconditional Surrender Amid Escalating Conflict
Israeli Airstrike Targets Iranian State TV in Central Tehran
President Trump is leaving the G7 summit early and has ordered the National Security Council to the Situation Room
Netanyahu Signals Potential Regime Change in Iran
Analysts Warn Iran May Resort to Unconventional Warfare
Iranian Regime Faces Existential Threat Amid Conflict
Energy Infrastructure Becomes War Zone in Middle East
Iran Conducts Ballistic Missile Launches Amid Heightened Tensions with Israel
Iran Signals Openness to Nuclear Negotiations Amid Ongoing Regional Tensions
Shock Within Iran’s Leadership: Khamenei’s Failed Plan to Launch 1,000 Missiles Against Israel
Trump's Anti-War Stance Tested Amid Israel-Iran Conflict
UK Deploys Jets to Middle East Amid Rising Tensions
Exiled Iranian Prince Reza Pahlavi Urges Overthrow of Khamenei Regime
Wreck of $17 Billion San José Galleon Identified Off Colombia After 300 Years
Iran Launches Extensive Missile Attack on Israel Following Israeli Strikes on Nuclear Sites
Israel Issues Ultimatum to Iran Over Potential Retaliation and Nuclear Facilities
Black Box Recovered from Air India Crash Site
Coinbase CEO Warns Bitcoin Could Supplant US Dollar Amid Mounting National Debt
Trump to Iran: Make a Deal — Sign or Die
Operation "Like a Lion": Israel Strikes Iran in Unprecedented Offensive
Israel Launches 'Operation Rising Lion' Targeting Iranian Nuclear and Military Sites
Israeli Forces Intercept Gaza-Bound Aid Vessel Carrying Greta Thunberg
IMF Warns of Severe Global Trade War Impacts on Emerging Markets
Syria to Reconnect to Global Economy After 14 Years of Isolation
Israel Confirms Arming Gaza Clan to Counter Hamas Influence
Global News Roundup: From Ukraine's strategic military strikes and Russia's demands and Tensions Escalate in Ukraine, to serious legal issues faced by Britons in Bali and Trump's media criticism, the latest developments highlight a turbulent landscape
U.S. Reduces Military Presence in Syria
Trump Demands Iran End All Uranium Enrichment in Nuclear Talks
Iran Warns Europe Against Politicizing UN Nuclear Report
Paris Saint-Germain's Greatest Triumph Is Football’s Lowest Point
OPEC+ Agrees to Increase Oil Output for Third Consecutive Month
Turkey Detains Istanbul Officials Amid Anti-Corruption Crackdown
Meta and Anduril Collaborate on AI-Driven Military Augmented Reality Systems
EU Central Bank Pushes to Replace US Dollar with Euro as World’s Main Currency
European and Arab Ministers Convene in Madrid to Address Gaza Conflict
U.S. Health Secretary Ends Select COVID-19 Vaccine Recommendations
Trump Warns Putin Is 'Playing with Fire' Amid Escalating Ukraine Conflict
India and Pakistan Engage Trump-Linked Lobbyists to Influence U.S. Policy
U.S. Halts New Student Visa Interviews Amid Enhanced Security Measures
Trump Administration Cancels $100 Million in Federal Contracts with Harvard
SpaceX Starship Test Flight Ends in Failure, Mars Mission Timeline Uncertain
King Charles Affirms Canadian Sovereignty Amid U.S. Statehood Pressure
×