BOSTON — It promised convenience, ease of storage and protection against serious COVID-19 illness. And by all accounts, Johnson & Johnson/Janssen’s single-dose vaccine is living up to those claims. But is all that coming with a price?
U.S. regulators now have the difficult task of figuring out whether six cases of cerebral blood clots that developed just weeks after immunization are an actual side effect of the vaccine.
“In the general population this condition exists in the absence of vaccination and is a very rare condition,” said Dr. Mark Poznansky, director of Mass General’s Vaccine and Immunotherapy Center. “When you start vaccinating lots of people, you can get these sort of findings. And it’s really incumbent upon the FDA to work out is it cause or is it just a random association?”
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That seemingly Herculean task begins with an in-depth look at the individual patients who developed the clots, Poznansky said, to determine if they had risk factors prior to vaccination.
“So a deep-dive into those patient’s histories, a deep-dive into what precisely the clotting disorder is, is what’s happening at this particular time,” Poznansky said. “It’s a case-by-case review in great depth.”
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In Europe, two similar reviews seem to have been conducted by separate research groups in Norway and Germany after the Astra-Zeneca COVID-19 vaccine was linked to some of the same kind of blood clots seen with J&J’s product.
Those researchers found that, in two groups of younger patients, clots seemed to develop in the brain and abdomen up to two weeks post-immunization. Of the 16 patients studied, nine died. Both groups published their findings in last week’s edition of The New England Journal of Medicine and concluded, separately, there was a link between the Astra-Zeneca vaccine and the clots, by virtue of an antibody reaction similar to that seen in a condition known as Heparin-Induced Thrombocytopenia (HIT).
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As for the danger to those immunized in the U.S. with the Johnson & Johnson product, it is likely minimal.
“All bets are off at this point. I would really stress this point, that this is under investigation,” Poznansky said.
Still, the CDC recommended that anyone vaccinated three weeks ago or less with the J&J formulation seek medical help if headaches, leg pain, abdominal pain or shortness of breath develop.
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