Scientists Uncover Link Between Deadly Blood Clots and Covid-19 Vaccines

In a groundbreaking discovery, researchers have found that the rare but deadly blood clots associated with Johnson & Johnson and AstraZeneca’s COVID-19 vaccines were caused by an autoimmune reaction in genetically susceptible individuals. This finding, reported in a letter to the New England Journal of Medicine, is expected to significantly impact future vaccine development. The scientists behind the study are now working to identify the specific component in the adenovirus-based vaccines that triggers the blood clots and aim to remove them through genetic engineering.

5 Key Points

  • Rare but deadly blood clots linked to J&J and AstraZeneca Covid-19 vaccines were caused by an autoimmune reaction in genetically susceptible individuals.
  • Adenovirus-based vaccines contain a component that can trigger blood clots in genetically susceptible people.
  • Researchers aim to identify the specific component and remove it through genetic engineering.
  • The immune reaction linked to the shot is considered a new disease, and more cases may be described as healthcare professionals become more familiar with the condition.
  • The mRNA vaccines made by Pfizer-BioNTech and Moderna were later found to be more effective at protecting against COVID-19 and have been updated to tackle more recent virus variants.

Scientists Discover Cause of Rare Blood Clots Linked to Covid Vaccines

The research, led by Tom Gordon, head of immunology at Flinders University in South Australia, has shed light on the cause of the rare blood clots linked to the J&J and AstraZeneca vaccines. Gordon stated that the immune reaction linked to the shot is “a new disease,” and he expects more cases to be described as hematologists and intensive care specialists become more familiar with the condition.

Impact of Blood Clots on Vaccine Distribution

The discovery of the blood clot complications significantly impacted the distribution of the J&J and AstraZeneca vaccines. Out of more than 18 million people who received the single-dose J&J vaccine, 60 cases of the clotting disorder were reported, resulting in nine deaths, according to the Yale School of Medicine.

The AstraZeneca vaccine faced similar challenges, with a small number of clot-related deaths leading to its withdrawal or restriction in several countries, including Denmark and Norway, in 2021. The European Commission ultimately withdrew the marketing authorization for the vaccine in March 2024.

The Role of mRNA Vaccines

Despite the setbacks the J&J and AstraZeneca vaccines faced, both played a crucial role in the early stages of the pandemic vaccination efforts. An analysis found that the AstraZeneca vaccine alone saved an estimated 6.3 million lives in 2021.

As the pandemic progressed, the mRNA vaccines developed by Pfizer-BioNTech and Moderna emerged as more effective alternatives, offering better protection against COVID-19 and being updated to tackle more recent virus variants.