Risk of blood clots is higher from Covid than from J&J shot, says doctor who worked on other vaccine trials

The risk of developing blood clots from Covid-19 is greater than the apparent likelihood of developing them from Johnson & Johnson‘s coronavirus vaccine, Dr. Purvi Parikh told CNBC on Tuesday.

Parikh, a New York-based allergist and immunologist, has worked as an investigator for other Covid vaccine trials, including Pfizer.

Looking at Tuesday’s FDA recommendation to pause use of J&J’s one-shot vaccine through that prism, Parikh said the temporary halt indicates that regulators’ “safety checks and balances are working.”

“For now, I would be careful with any of these conspiracy theories and again with the panic,” said Parikh, a clinical assistant professor in the Department of Medicine at NYU Grossman School of Medicine.

“You’re much more likely to clot from the real Covid-19 virus, which is about 1 in 20 people hospitalized or even 1 in 100 recovering at home. That’s far more likely,” she added on “Squawk on the Street,” citing data from industry group Thrombosis Canada.

Parikh’s comments came hours after the Food and Drug Administration and Centers for Disease Control and Prevention asked states to temporarily stop administering J&J’s vaccine after six women in the U.S. who got it developed a rare but serious blood-clotting disorder. One of the recipients died, and another is in critical condition.

Nearly 7 million people have received the J&J shot. There are no other known cases besides the six being reported by federal health regulators. The J&J vaccine uses an adenovirus delivery system. An adenovirus is a common type of virus that typically causes mild cold symptoms.

Asked whether J&J’s vaccine could still be given to Americans while the six known cases of blood clots are investigated, Parikh said it’s best to halt them for now.

“They’re not revoking the emergency use authorization. They’re not saying that it’s a bad vaccine. Pauses are completely normal,” she explained. “As we vaccinate more people — millions versus tens of thousands in the clinical trials — these pauses will occur. I think they are the right move, that way we know for sure it’s safe to move forward.”

However, Parikh said that when looking “at the big picture” based on currently available information, “the benefits still far outweigh the risks of this vaccination.”

White House chief medical advisor Dr. Anthony Fauci told reporters Tuesday there have not been any “red flag signals” from the two-shot vaccines from Pfizer or Moderna. Those two vaccines, the only other ones cleared for emergency use in the U.S., employ a new approach to vaccines that uses genetic material to provoke an immune response.