Doctors say as we continue to vaccinate millions, rare complications will become more evident.By Dr. Maria Simbra

PITTSBURGH (KDKA) — European regulators have determined there is a link between AstraZeneca’s COVID-19 vaccine and blood clots.

“Normally, there’s about usually two to four of these cases out of every million people. And when they looked at the patients that were vaccinated, that number was about six cases per million,” said Dr. Marc Itskowitz, a primary care internist at the Allegheny Health Network. “So even though that’s a small increase, it did get their attention.”

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The type of blood clot linked to this particular vaccine is rare. These clots occur in the veins of the brain and abdomen.

“The vaccine may be stimulating an unusual type of antibody that is related to this type of blood clot,” Dr. Itskowitz said.

Researchers are still trying to figure out why the clots are happening. Eighteen cases have been fatal.

“The concern regarding blood clots is limited to the AstraZeneca vaccine,” he said. “It is true the [Johnson & Johnson vaccine] also uses a virus vector technology. But keep in mind, J&J has used this technology with other vaccines in the past, and we haven’t seen this type of complication.”

The regulators in Europe say that the unusual clots with levels of certain blood cells being low should be listed as a side effect. They also stress that the benefits outweigh the risks. The two-dose immunization is 76% effective at preventing illness with COVID.

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Some countries are already limiting the AstraZeneca vaccine to older people since most of the clots have been in people younger than 60.

“It does appear to be more of a concern in young people, where the benefit from the vaccine may not be as great as it is in the older population,” said Dr. Itskowitz.

The AstraZeneca product costs $4 per dose, compared to $10 to $40 for the others. And it can be refrigerated.

Nevertheless, Dr. Itskowitz does not expect emergency use authorization on the horizon.

“We are now vaccinating four million patients a day using J&J, Moderna and Pfizer. I think we should stick with these three vaccines for now,” the doctor said.

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He says as we continue to vaccinate millions, rare complications, like these clots, will become more evident.