A panel of advisers to the Facilities for Illness Management and Prevention has beneficial lifting the pause on the Johnson & Johnson Covid-19 vaccine for all adults whereas including a warning label about a rare but dangerous blood clotting dysfunction. However a central thriller persists: How may a vaccine that has been given to nearly eight million people trigger the facet impact in only a few of them?

There’s no clear reply but, however Dr. Andreas Greinacher, a researcher at College Medication Greifswald in Germany, is main one effort to search out out. At a information convention on Tuesday, he mentioned that he had reached an settlement with Johnson & Johnson to examine the parts of the vaccine to see if it may disrupt the traditional blood clotting course of beneath sure uncommon circumstances.

“We simply agreed that we wish to work collectively,” he mentioned.

It’s doable, Dr. Greinacher mentioned, that the Johnson & Johnson vaccine could cause uncommon uncomfortable side effects by the identical course of that he suspects is responsible for similar side effects from the AstraZeneca vaccine. The primary ingredient in each vaccines are innocent viruses generally known as adenoviruses, which slip into human cells and ship a coronavirus gene that can later trigger an immune response.

On Tuesday, Dr. Greinacher and his colleagues launched a report on how the AstraZeneca vaccines may set off the facet impact. The research has not but been revealed in a scientific journal.

The scientists discovered that parts within the AstraZeneca vaccine may follow a protein that platelets launch in the course of the formation of blood clots. These clumps of molecules may very well be seen by the physique as international invaders, the scientists speculated, triggering a cascade of reactions that trigger platelets to show into harmful clots.

Dr. Paul A. Offit, a vaccine knowledgeable at Youngsters’s Hospital of Philadelphia who was not concerned within the research, discovered Dr. Greinacher’s research intriguing however removed from the ultimate phrase. “He throws out lots of potentialities,” he mentioned.

Dr. Offit mentioned it was not clear which of the various elements the researchers studied may clarify the uncommon blood clots in individuals vaccinated with AstraZeneca’s doses. “It’s like sipping from a fireplace hose,” he mentioned.

At a information convention on Tuesday, Dr. Greinacher mentioned that the analysis may level to methods, within the AstraZeneca vaccine, of reducing the danger of the clots or treating the uncomfortable side effects. However he emphasised that the small threat of these uncomfortable side effects was strongly outweighed by the safety that vaccines reminiscent of AstraZeneca’s present towards Covid-19.

“Not being vaccinated is much extra harmful than being vaccinated and in danger for this hostile drug response,” he mentioned.