US regulators on Tuesday recommended an immediate pause of Johnson & Johnson's vaccine rollout.
Six women have developed rare blood clots following J&J's shot, but experts aren't worried yet.
Johnson & Johnson's coronavirus vaccine rollout has hit several major snags this month.
On Tuesday, US regulators recommended an immediate pause of the company's vaccine rollout so that they can investigate six cases in which women developed rare blood clots within two weeks of receiving J&J's shot. One of those women died and a second is in critical condition.
European regulators also announced last week that they were investigating Johnson & Johnson's shot for links to rare blood clots.
To make matters worse, a vaccination site in Colorado, three sites in North Carolina, and one in Georgia all temporarily stopped administering Johnson & Johnson's shot last week after about 45 people in total experienced minor adverse reactions involving nausea, dizziness, fainting, or lightheadedness.
That all followed the news that a Maryland manufacturing plant run by Emergent Biosolutions had ruined 15 million doses of the J&J vaccine after plant workers accidentally mixed up some vaccine ingredients in March. The New York Times reported last week that 62 million of the company's vaccine doses must be checked for contamination.
Still, some experts say there's little reason to doubt the shot's safety yet.
"You don't want to be fueling unnecessary worries about the safety of vaccines when you're still seeing an enormous outbreak and death rates all over the world from COVID," Art Caplan, a bioethicist at New York University, told Insider before Tuesday's announcement.
The link between J&J's shot and blood clots remains tenuous
All six women who developed blood clots in response to J&J's vaccine were between the ages of 18 and 48. Each had a rare type of blood clot in the brain called central venous sinus thrombosis (CVST), along with low levels of platelets (colorless blood cells that help clots form).
At a Tuesday press briefing, Peter Marks, director of the Food and Drug Administration's Center for Biologics Evaluation and Research, said the rare clotting may have been caused by an immune response to the vaccine, though no definitive link has been drawn yet.
While blood clots are often treated with a blood-thinning drug called heparin, FDA officials said on Tuesday that administering heparin may be dangerous to those who develop CVST. That's partly why the US is pausing the J&J rollout.
"We are recommending a pause in the use of this vaccine out of an abundance of caution," the FDA and Centers for Disease Control and Prevention said in a joint statement on Tuesday. "This is important, in part, to ensure that the healthcare provider community is aware of the potential for these adverse events and can plan for proper recognition and management due to the unique treatment required with this type of blood clot."
FDA commissioner Janet Woodcock said the pause would likely last "a matter of days."
Around 6.8 million doses of J&J's vaccine have been administered in the US so far. That means fewer than one blood clot case has been observed per every 1 million shots.
J&J said in a statement that it's working with regulators and medical experts to look into the blood-clot reports. Experts are still examining whether there's a cause-and-effect relationship.
"It isn't really clear how many people get blood clots anyway," Caplan said. "That makes it hard to know whether it's connected to vaccination."
In the meantime, the European Union's health regulator, the European Medicines Agency (EMA), is carrying out its own investigation of the same blood-clot cases reported by the FDA. The EU authorized Johnson & Johnson's vaccine in March, but J&J announced Tuesday that it would delay its rollout of the vaccine in Europe.
Earlier this month, the EMA announced that potentially fatal blood clots might be a rare side effect of AstraZeneca's vaccine, which has been authorized in more than 115 countries but not yet in the US. Both that shot and Johnson & Johnson's are viral-vector vaccines, which introduce a coronavirus gene into the body using a genetically engineered common-cold virus. Scientists don't know whether the platform itself could be linked to clotting.
Still, any risk of clots should be weighed against the risk of getting COVID-19, Caplan said.
"If I live in Brazil and I'm still seeing 3,000 deaths a day, and somebody said to me, 'We're going to pull AstraZeneca vaccine out of here because we found somebody who died of a blood clot that might be related to the vaccine,' I'd say, 'You better recalculate your risk-benefit ratio,'" he said.
People could get dizzy or nauseous for many reasons
Experts are far less concerned about the reports of nausea and fainting at vaccination sites.
Those side effects are "absolutely trivial," Caplan said. Although they aren't common responses to coronavirus vaccines, they aren't abnormal, either.
"When you see these clusters [of side effects], they usually are worked out and have no relation to the vaccine," Arnold Monto, an epidemiologist at the University of Michigan's School of Public Health, told Insider. Monto chairs the Food and Drug Administration's Vaccine Advisory Committee, which voted to recommend the Pfizer, Moderna, and Johnson & Johnson shots.
Most of the negative reactions to Johnson & Johnson's shot occurred within 15 minutes after a person got vaccinated, public-health officials in Colorado, Georgia, and North Carolina reported. In total between the three states, seven people were taken to hospitals for observation. As of last week, all but one had been released and everyone was expected to fully recover.
Officials haven't yet pinpointed why these clusters of adverse reactions were identified within such a short time frame. But they've emphasized that there's no reason to be concerned about the shot itself.
In a news release, Georgia's public health commissioner, Kathleen Toomey, said the state was looking into "what may have caused the reactions, including the conditions at the fairgrounds such as heat and the ability to keep the site cool."
Caplan said it's possible that the people who felt dizzy or nauseous were elderly or had underlying health conditions that may have predisposed them to adverse reactions. And once one site reports a cluster of patient reactions, that makes others more likely to look for them and take swift action.
Regardless, Monto said, the fact that adverse reactions are being reported and investigated shows that local officials are working hard to minimize harm.
"Any pause in vaccination shows that the system is working because we're not trying to sweep anything under the rug," he said.
In a statement, Johnson & Johnson told Insider that it takes all adverse reactions seriously. The company said it would "carefully assess the events" and share any findings with the FDA.
"There is no greater priority than the safety and well-being of the people we serve," the statement said.
A low supply of Johnson & Johnson shots
The White House said on Tuesday that pausing the J&J rollout would "not have a significant impact on our vaccination plan," since the two other vaccines authorized in the US - from Pfizer and Moderna - are "more than enough supply to continue the current pace of vaccinations."
J&J shots have accounted for less than 5% of vaccinations so far in the US, the White House said.
The total supply of the shot allocated to states and other jurisdictions was already expected to drop by 85% this week, to around 1.5 million doses. That's in part because quality-control managers must test 62 million doses to see if they can be salvaged following the manufacturing mix-up at the Emergent Biosolutions plant. The FDA must also certify that the plant can release more doses to the public.
Johnson & Johnson promised to ship 24 million doses in the US this month, but it's unclear if the company will meet that goal.
Allison DeAngelis contributed reporting.
This story has been updated with new information about the pause in J&J's vaccine rollout. It was originally published on April 10.
Read the original article on Business Insider