German scientists claim to have discovered the source of rare blood clots linked to COVID-19 vaccines developed by Johnson & Johnson, the University of Oxford, and AstraZeneca. As a result, They also believe they have discovered a way for the producers to modify their shots so that the clots no longer occur.
The researchers, in a study not yet reviewed by experts, said COVID-19 vaccines that employ adenovirus vectors – cold viruses used to deliver vaccine material – send some of their payloads into the nucleus of cells, where some of the instructions for making coronavirus proteins can be misread. The resulting proteins could potentially trigger blood clot disorders in a small number of recipients, they suggest.
In their paper, researchers from the Goethe-University of Frankfurt and other institutions explained that vaccines based on a different technology known as messenger RNA (mRNA), such as those developed by BioNTech SE with partners Pfizer Inc and Moderna Inc, deliver the genetic material of the coronavirus spike protein only to the fluid found inside cells, rather than the nucleus of the cells. “All mRNA-based vaccines should represent safe products,” the paper said.
The paper suggests that vaccine makers using adenovirus vectors could modify the sequence of the spike protein “to avoid unintended splice reactions and to increase the safety of these pharmaceutical products.”
Johnson & Johnson, in an emailed statement, said: “We are supporting continued research and analysis of this rare event as we work with medical experts and global health authorities. We look forward to reviewing and sharing data as it becomes available.” AstraZeneca declined to comment.