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US halts launch of J&J vaccine after 6.8 million people had rare blood clots

U.S. federal health officials are taking an urgent break in the administration of Johnson & Johnson’s COVID-19 vaccine following rare reports of blood clots in people who received the shot. U.S. officials recommend that, for now, states also stop firing.

Of the more than 6.8 million people vaccinated with the Johnson & Johnson coup in the United States, six have developed severe blood clots in the breasts that drain blood from the brain, U.S. Food and Drug Administration officials and Centers for Disease Control said. disease control and prevention. 13 in a press release. This condition, called cerebral venous sinus thrombosis or CVST, is linked to low levels of platelets in the blood after vaccination.

The length of the break will largely depend on the outcome of an expert review of the cases, but it could be a matter of days, said Janet Woodcock, the FDA's acting commissioner, in an April 13 call with reporters. The CDC Advisory Committee on Immunization Practices will meet on April 14 to discuss cases and potentially update their recommendations for use.

U.S. action comes less than a week after the European Medicines Agency announced that its experts had found a link between a COVID-19 vaccine developed by AstraZeneca and Oxford University and conditions such as CVST (SN: 4/7/21 ). In the European Union and the United Kingdom, most rare blood clots have occurred in vaccinated women under 60 years of age. But risk factors remain unclear, according to the EMA. Health officials have recommended that CVST and other unusual clots be listed as a rare side effect of the AstraZeneca vaccine.

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In the United States, all six cases of CVST were in women under the age of 50 and occurred six to 13 days after vaccination. One person is dead and another is in critical condition. “These events seem to be extremely rare,” Woodcock said. She noted that, as with the AstraZeneca shot, there are very few cases with the Johnson & Johnson vaccine to draw conclusions about who is most at risk of developing clots. Johnson & Johnson has delayed the launch of its vaccine in Europe, the pharmaceutical company reported on April 13 in a press release.

The pause in vaccine use is “out of sheer caution” until health officials review the cases, Woodcock said. It will give experts time to prepare the health care system so that health care providers can know the options for treating patients, as CVST requires different medical treatments than other types of clots. Experts can also notify vaccinated people about the symptoms to watch out for, as well as keep an eye on new reports that may appear.

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“These clots are very different from normal blood clots,” says Elliott Haut, a blood clot expert and trauma surgeon at the Johns Hopkins School of Medicine. “It’s a tough place to be,” but with figures that so far showed a rate of 1 case of clotting per million people, the benefits of the vaccine still outweigh the risks, he says.

COVID-19 itself can cause clots in about one-fifth of hospitalized patients and has killed nearly 3 million people worldwide in the past year (SN: 02/11/20). Other medications such as hormonal birth control also carry risks of blood clots, but people still take contraceptives, says Haut.

Symptoms such as severe headache, leg or abdominal pain, or shortness of breath in the three weeks following vaccination with the Johnson & Johnson vaccine could be a sign of a dangerous clot, said Anne Schuchat, CDC deputy director, in the May 13 call. April. These side effects are different and appear much later than the simple symptoms that result from the immune response to the jab in the days following the shot.

Vaccine safety is a priority, so officials are taking coagulation reports seriously, Woodcock said. No cases of coagulation have been reported in people vaccinated with COVID-19 vaccines based on the Modern or Pfizer mRNA of 180 million doses administered in the United States.

Both AstraZeneca and Johnson & Johnson shots are adenovirus-based vaccines. The shots use a form of adenovirus that is normally designed (which usually causes the common cold but is altered so as not to cause disease) to deliver instructions to the cells to make the coronavirus ear protein. This is what triggers the immune system to recognize an infection. It is possible, though far from proven, that rare clots are linked to this type of vaccine. But investigators still don’t know, said Peter Marks, director of the FDA’s Center for Biological Assessment and Research in the call with reporters.

It is also unknown how vaccines can cause clots. Studies suggest that an immune response to vaccines may stimulate platelets to come together, but it is also far from clear.

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