The S.C. Department of Health and Environmental Control halted the rollout of the single-dose Johnson & Johnson COVID-19 vaccine in South Carolina at the recommendation of federal health officials investigating reports of potentially dangerous blood clots.
In a joint statement April 13, the Centers for Disease Control and Prevention and the Food and Drug Administration said they were investigating unusual clots in six women that occurred six to 13 days after vaccination.
The clots occurred in veins that drain blood from the brain and occurred together with low platelets. All six cases were in women between the ages of 18 and 48. One person died, and all of the cases remain under investigation.
Given millions of people have taken the vaccines and the clots are known to happen naturally in the population, a cause-and-effect relationship between the clots and the vaccines hasn't been established.
But the reports appear similar to a rare type of clotting disorder that European authorities say is possibly linked to another COVID-19 vaccine not yet cleared in the U.S. from AstraZeneca.
As of April 10, about 87,000 South Carolinians had received the J&J vaccine. Another 35,000 doses are in the state's inventory but yet to be delivered to people, according to DHEC. The vast majority of people who have already gotten the shot have had either no or mild side effects.
The South Carolina health agency announced in an April 13 statement it is calling providers who are giving out the J&J vaccine to stop for the moment and is working on reshuffling upcoming events that featured the manufacturer's doses.
"Our top priority is protecting the health and safety of the public," DHEC said in a statement. "This pause is evidence of very close safety monitoring as part of the strict quality assurance that is in place to ensure patient safety."
Dr. Edward Simmer, DHEC's director, said during a media briefing he thinks "the impact will be minimal, and we're working to minimize it even further." Simmer added that the doses are in storage and could be deployed if the FDA and CDC lift their recommendation to pause distribution.
The other two authorized vaccines, from Moderna and Pfizer, make up the vast share of COVID-19 shots administered in the U.S. and are not affected by the pause. In South Carolina, just 3 percent of all doses that have been given were made by J&J.
In its response to the news, J&J said it would also delay the rollout of its single-dose vaccine in Europe.
"We have been working closely with medical experts and health authorities, and we strongly support the open communication of this information to health care professionals and the public," the firm said in its statement.
The CDC's Advisory Committee on Immunization Practices will meet April 14 to discuss the cases, and the FDA has also launched an investigation into the cause of the clots and low platelet counts.
"Right now, I'd like to stress these events appear to be extremely rare. However, COVID-19 vaccine safety is a top priority," acting FDA Commissioner Janet Woodcock said at a news conference April 13. "We take all reports of adverse events following vaccination very seriously."
Recommendations call for people given the J&J vaccine who are experiencing severe headache, abdominal pain, leg pain or shortness of breath within three weeks after receiving the shot contact their health care provider.
Dr. Helmut Albrecht, an infectious disease physician at Prisma Health, the largest provider of COVID-19 vaccines in South Carolina, said blood clotting is not necessarily a rare event in and of itself, though it can be a serious problem for patients.
He noted the chances of getting a blood clot from COVID-19 are higher than getting one from the J&J vaccine.
"Out of an abundance of caution this was halted to see if this is truly related," Albrecht said. "This will cost a lot more lives than continuing it."
Asked if the government was overreacting to six cases out of more than 6 million vaccinations, the CDC's Dr. Anne Schuchat said recommendations will come quickly.
Because these unusual clots require special treatment, "it was of the utmost importance to us to get the word out," she said. "That said, the pandemic is quite severe and cases are increasing in lots of places and vaccination's critical."
Until now, concern about the unusual blood clots has centered on the vaccine from AstraZeneca, which has not yet received authorization in the United States. Last week, European regulators said they found a possible link between the shots and rare blood clots.
The J&J and AstraZeneca vaccines are built on similar technology, Albrecht said, whereas the Pfizer and Moderna options have completely different building blocks.
As part of its recommendations April 13, U.S. health authorities cautioned doctors against using a typical clot treatment, the blood-thinner heparin.
"In this setting, administration of heparin may be dangerous and alternative treatments need to be given," the FDA and CDC said.
European authorities investigating the AstraZeneca cases have concluded clots appear to be similar to a very rare abnormal immune response that sometimes strikes people treated with heparin, leading to a temporary clotting disorder.
Doctors would treat these kinds of unusual clots like they treat people who have the heparin reaction — with different kinds of blood thinners and sometimes an antibody infusion, said Dr. Geoffrey Barnes, a clot expert at the University of Michigan.
Even without J&J's vaccine, White House officials said they remain on track to have enough supplies to vaccinate most American adults by the summer.
"We believe there's enough vaccine in the system — Moderna and Pfizer — for all Americans who want to get vaccinated by May 31 to do so," said Jeff Zients, the White House's COVID-19 response coordinator.
The J&J vaccine received emergency use authorization from the FDA in late February with great fanfare, with hopes that its single-dose and relatively simple storage requirements would speed vaccinations across the country. Yet the shot only makes up a small fraction of the doses administered in the U.S. as J&J has been plagued by production delays and manufacturing errors at the Baltimore plant of a contractor.
Last week, the drugmaker took over the facility to scale up production in hopes of meeting its commitment to the U.S. government of providing about 100 million doses by the end of May.
U.S. stock markets initially dropped on the J&J news, but some indices were up slightly by late morning. Johnson & Johnson shares were down nearly 3 percent, an unusually big drop for the drug giant, with more shares changing hands in the first two hours than on an average day.
The Associated Press contributed reporting.