TORONTO -- Dr. Andreas Greinacher led the team that discovered the link between the AstraZeneca vaccine and a rare blood clotting disorder, but he wants people to know the risk of developing the clots is low.

Greinacher found that in some patients, the AstraZeneca vaccine was triggering antibodies that set off a platelet response. That means the the antibodies made the platelets, small blood cells that help form clots to stop bleeding, behave as though they were treating a wound and trigger clotting.

At a press conference on Wednesday, Greinacher said that the causal link is still unknown, and there could be co-factors in the small number of patients who developed vaccine-induced prothrombotic immune thrombocytopenia (VIPIT). VIPIT is the name given to the type of clotting that seems to occur as a rare reaction to the AstraZeneca vaccine.

鈥淚t could very well be that in these individual patients are two or three co-factors present at the same time, which together at the time point of vaccination trigger these antibodies,鈥 he said.

While his team continues to investigate what exactly causes this reaction, Greinacher said that there are far fewer people developing this antibody response than are getting sick with COVID-19.

鈥淭he number of individuals being severely sickened by the pandemic, by COVID-19, outnumber those who suffer from the vaccination reaction by several orders of magnitude,鈥 he said.

While he said it is not up to him who is approved for the vaccine and who isn鈥檛, he doesn鈥檛 think stopping vaccinations is the right decision.

鈥淚t would be dangerous to stop vaccination, only because of the fear, for a very rare adverse event,鈥漢e said.

Thinking about the dangers we face each day, driving a car on a busy highway, riding a bicycle in major cities, they are far greater risks than the clotting issue associated with the AstraZeneca vaccine, he said.

鈥淩unning down the road with a motorcycle is by far, far, far more dangerous than getting the vaccine,鈥 he said. 鈥淭ake 1.4 million motorcycle riders, let them drive two weeks, how many severe accidents, you will see.鈥

For a medical comparison, he points to the use of the blood thinning medication heparin in hospitals. There are people who suffer adverse reactions to heparin, similar to the reaction to the AstraZeneca vaccine, but to stop using it altogether would be catastrophic.

Greinacher said that to stop the use of the clotting treatment in hospital would result in many more deaths due to fatal embolisms and other clot-related complications.

Within the span of two weeks, Greinacher and his colleagues were able to develop a screening test, a test to confirm the response in a lab and now, a potential treatment.

鈥淭he first anecdotal feedbacks I receive from treating physician, it seems to work quite well,鈥 he said.

The focus now for Greinacher and his colleagues is determining how the vaccine is associated with, or induces, this response in the body.

鈥淚 have to say very clearly, there is no direct link that the vaccine itself is inducing the antibody, it could be that the vaccine is triggering something else in the human body, which then is modifying the immune system, which is then starting to produce the antibodies,鈥 he said.

鈥淚t's too early to make a really clear correlation and very clear association between the vaccine and formation of the antibodies,鈥 he added.

His message is clear: While there is a risk of having an adverse reaction to the AstraZeneca vaccine, the risk is so small that people shouldn鈥檛 be concerned about getting the vaccine.

鈥淭o stop or to avoid vaccination, only for the fear of getting an extremely rare, adverse reaction would be completely wrong.鈥