People who received the Janssen vaccine from Johnson & Johnson are more likely to develop blood clots in their brains, a new study has found.

Blood Clot Study

Researchers compared the incidence of blood clots in brains before and during the pandemic in a study published in JAMA Internal Medicine. They focused on this matter to put into context the rate of this adverse effect in relation to the effectiveness of the vaccine when preventing COVID-19.

The team led by Aneel A. Ashrani, MD, MS, of the Mayo Clinic in Rochester, did a population-based cohort study in which they first gathered data on all cerebral venous sinus thrombosis (blood clot in the brain) cases in Olmsted County, Minnesota from Jan. 1, 2001 through Dec. 31, 2015. They then compared it to the data they collected from vaccinated people from Feb. 28, 2021 to May 7, 2021.

The researchers found that people who got the Janssen jabs had a “significantly higher” brain blood clot incidence rate. The highest risk was noted in women between 30 and 49, as the blood clots were notable within 15 days of their vaccination

J&J vaccine recipients were said to be 3.5 times more likely to develop cerebral venous sinus thrombosis after the analysis of the data. The adjusted rates for the prepandemic incidence was 2.46 per 100,000 people in Olmsted County, while the pandemic incidence was 8.65 cases per 100,000 people, as per Washington Times.

Janssen Vaccine Rollout

In April, federal authorities had to pause the rollout of the J&J vaccine after reports of the potentially fatal side effect emerged, particularly in young women. At the time, six cases of a rare and severe type of blood clotting were reported following the administration of the vaccine.

However, the rollout quickly resumed within the same month after a thorough safety review by the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices and the U.S. Food and Drug Administration.

Both the CDC and FDA said they have confidence that the Janssen vaccine is safe and effective in preventing COVID-19 and that the potential benefits outweigh the potential risks that come with the vaccine in individuals 18 years and above.

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