It's the potential finding that medical doctors said could help understand what happened to the six American women who developed blood clots with the vaccine. The European Medicines Agency points to an immune response.
"One plausible explanation for the combination of blood clots and low blood platelets is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin called heparin induced thrombocytopenia, HIT," said an EMA press release.
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"The current hypothesis is that it may be an autoimmune response that causes the platelets to clump together," said Dr. Philip Grant, M.D, an infectious disease specialist with Stanford University.
Dr. Grant was the principal investigator of the Johnson and Johnson trials out of Stanford. He believes these findings show how rare blood clots can occur even without the vaccine.
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"It happens one out of 100,000 people per year. It is more often in women than in man. It's in this age group that it happens so the vaccine slightly increases ones annual risk of a very rare condition," said Dr. Grant.
The European Medicines Agency took into account the data from the U.S cases. Dr. Malcolm John of UCSF says those cases could lead to an explanation, but they need to be investigated closely.
"It is causing platelets to be removed from the body and it is also causing for platelets to become activated potentially and that is what is causing the clotting," said Dr. John.
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Dr. John led an effort to vaccinate the Black community in San Francisco with the Johnson and Johnson vaccine. In three to four weeks, more than 500 people were vaccinated with this shot and no reports of blood clots have been flagged.
"We have not heard of any clotting complications with any of the patients that have been in our vaccine clinics and I believe the same is true for UCSF in general," said Dr. John.
Dr. Grant says there is still a slight risk during the first two weeks of the vaccination but says the benefit outweighs the risk.
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Luz Pena: Do you feel comfortable lifting that pause on the J&J vaccine?
Dr. Grant: "Absolutely, and I think that real question was the whole pause worthwhile."
Both doctors agreed that there is still more work to be done to understand exactly what is leading to these rare blood clots.
Dr. Grant says the FDA could put a warning to let people know of this possibility and let the public decide.
According to Dr. Fauci, a decision about the Johnson and Johnson vaccine could be made by Friday when the U.S. Centers for Disease Control and Prevention's vaccine advisory panel meets.
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