CDC, FDA lift pause on Johnson & Johnson COVID vaccine. What to know
The Centers for Disease Control and Prevention and the U.S. Food and Drug Administration have lifted a pause placed on the Johnson & Johnson COVID-19 vaccine, officials announced in a joint press conference Friday evening.
The pause was initiated after several women developed blood clots within two weeks of vaccination.
“This vaccine was shown to be safe and effective for the vast majority of people,” CDC Director Rochelle Walensky said.
J&J shots can continue as soon as Saturday, officials said, but the label will be updated with a warning of blood clot risks.
”Together, both agencies have full confidence that this vaccine’s known and potential benefits outweigh its known and potential risks,” FDA acting Commissioner Janet Woodcock said.
The announcement comes just hours after a federal advisory committee recommended the move.
The recommendation did not include any new restrictions based on age or gender. Anyone over the age of 18 can receive the shot.
Officials agreed that the benefits of vaccination against COVID-19 outweighed the risks of developing blood clots, adding that a one-dose vaccine plays an important role in protecting vulnerable communities, such as the homeless and rural workforce, where returning for second shots may be unfeasible.
In total, there have been 15 cases of the clots following vaccination with the one-dose shot among nearly 8 million administered vaccines as of April 21. All of those cases were women aged 18 to 48 years old. Three have died and seven remain hospitalized.
The earlier vote in support of lifting the pause by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices, a group of medical and public health experts, was to advise the U.S. Food and Drug Administration and the CDC, which make their own decisions.
The Johnson & Johnson COVID-19 vaccine pause began April 13, lasting about two weeks.
The reported rate of the blood clot condition appeared to “exceed” the rates that naturally occur in women of the same age group by about threefold, the ACIP said.
However, Dr. Jean Connors, a hematologist at Brigham and Women’s Hospital in Boston, told the Wall Street Journal that the risk of blood clots is much higher from COVID-19 itself than from the Johnson & Johnson shot — a fact other experts have agreed with. About 15% to 20% of coronavirus patients who are admitted to intensive care units develop blood clots, Connors told the outlet.
Both the FDA and CDC have said the condition, called cerebral venous sinus thrombosis (CVST), is “extremely rare” after getting the Johnson & Johnson shot. However, the condition is coupled with low blood platelet counts, which together make a pattern that’s even more rare, experts say.
The events are similar to those reported in Europe following the administration of the AstraZeneca COVID-19 vaccine, which has not been authorized for emergency use in the U.S.
Of 2.7 million Pfizer doses and 2.5 million Moderna doses administered as of April 17 in the U.S., a total of five “potential” cases of CVST have occurred, but they do not include the low blood platelet counts seen in the cases following Johnson & Johnson vaccination.
Johnson & Johnson said last week that there was insufficient evidence to conclude its vaccine caused the reported blood clots.
What do experts think is causing the blood clots after J&J shots?
Scientists say the vector, or method of delivery, of the Johnson & Johnson COVID-19 vaccine may be behind the blood clots, but there isn’t enough evidence yet to make such a conclusion.
The shot, just like the AstraZeneca COVID-19 vaccine, is a viral vector vaccine. It works by delivering a harmless DNA virus called an adenovirus that has been genetically modified so it cannot make copies of itself in humans or cause disease.
This modified virus carries specific instructions into the body’s cells that teach them how to make the spike protein the novel coronavirus uses to infect people, triggering the production of antibodies.
Evidence from Europe shows this process may be sparking the production of antibodies against platelet factor 4, a protein that is known to cause blood clots. Still, much remains unknown about the relationship between the Johnson & Johnson vaccine and the recent cases of blood clotting.
This method is different from how the Pfizer and Moderna shots work. Instead of DNA, they insert mRNA — a molecule already found in the body — which stores directions that teach our cells to make copies of the coronavirus spike protein, sparking the creation of antibodies without the assistance of a separate harmless virus.
What is cerebral venous sinus thrombosis and its symptoms?
The condition occurs when a blood clot forms in the brain, preventing blood from draining out of it and causing blood cells to break and leak into brain tissue. Medically, this is known as a cerebral hemorrhage.
“It is like water in a reservoir overflowing into the surroundings or like a ruptured dam,” according to the University of Michigan Comprehensive Stroke Center.
The condition is essentially a rare form of stroke that causes symptoms such as numbness, weakness in the arm or legs, trouble speaking, blurred vision, shortness of breath, leg pain, severe headache and abdominal pain.
Medications that contain estrogen such as birth control pills, drugs for chemotherapy, inherited blood clotting disorders and pregnancy are some of the most common causes of CVST.
The condition is typically diagnosed with an MRI or CT scan. There are about 10 to 15 cases of CVST per million people.
Generally, CVST is more common among women, particularly those between the ages of 20 and 35.
Typically, blood clots are treated with an anticoagulant called Heparin, but the medication may be dangerous in the context of Johnson & Johnson vaccination, and alternative treatments should be given, federal health officials say.
This story was originally published April 23, 2021 at 4:49 PM with the headline "CDC, FDA lift pause on Johnson & Johnson COVID vaccine. What to know."
