Sunday, June 13, 2021

in-focus

CDC advisers seek more data on rare blood clots before deciding whether to resume Johnson & Johnson shots


WASHINGTON - A federal vaccine advisory committee said Wednesday it wanted more data before deciding whether to resume use of Johnson & Johnson's coronavirus vaccine, leaving in place a pause that federal officials had recommended because of a rare and severe type of blood clot identified so far among six of the 7.5 million people who received the shot.

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The move means the single-shot Johnson & Johnson product will remain on the shelf for at least a week.

At a hastily arranged emergency meeting a day after federal officials recommended a pause in use of the vaccine, advisers to the Centers for Disease Control and Prevention agreed to reconvene within 10 days, acknowledging the urgency of making a decision about a vaccine that is a key part of the strategy to end the pandemic in the United States and globally.

The Advisory Committee on Immunization Practices reviewed details about six cases of blood clots in women who were between the ages of 18 and 48. The women developed symptoms, most often headaches, six to 13 days after vaccination. One vaccine recipient, a Virginia woman, died in March, and another is in critical condition, health officials have said. Two have been discharged and three remain in the hospital.

Instead of voting on a recommendation about whether and how the vaccination campaign could be restarted, panel members said they wanted more information on the risks, cause and frequency of the rare brain blood clots. When the panel reconvenes, members could vote at that time to recommend the vaccine for people 18 and older, continue an overall pause or pause use for certain age groups.

"We are very fortunate, because we have multiple other alternatives in the U.S. to help stop this pandemic. We have very good, well-proven alternatives where we are not seeing safety signals," said Helen Keipp Talbot, an associate professor of medicine at Vanderbilt University and committee member. "I think that puts us in a little bit of a different position, and we can be much more cautious and thoughtful and use the old model of, 'First, do no harm.'"

Beth Bell, a global health expert at the University of Washington who leads the panel's coronavirus vaccine work group, said she did not want to take a vote Wednesday for fear of undermining support for the easier-to-use vaccine.

A national Economist-YouGov poll found that public confidence in the Johnson & Johnson vaccine might already be declining. The share of people who thought the vaccine was "very or somewhat unsafe" increased in a matter of days, from 26% of people during the past weekend and Monday to 39% on Tuesday after federal officials recommended a pause.

The vaccine has been viewed as a powerful tool for building immunity among vulnerable communities, such as homebound people or homeless populations who might not be able to return for a second shot. The decision will also almost certainly reverberate around the globe.

The vaccine was a large part of the U.S. vaccination strategy, and the drugmaker has delayed the rollout of its vaccine in Europe as the investigation continues. South Africa suspended use of the shot.

But some public health officials said Wednesday's lack of a recommendation is a decision that will have consequences.

"The extension of the pause will invariably result in the fact that the most vulnerable individuals in the United States who were prime candidates for the Johnson & Johnson vaccine will remain vulnerable. The most at risk will remain at risk, and those who would benefit immediately from vaccination will remain unvaccinated for an unknown period of time," said Nirav Shah, director of the Maine Center for Disease Control and Prevention. "That would come at a period where the United States is still logging 5,000 deaths in the past seven days across the country."

A CDC official and a Johnson & Johnson executive described the six cases in the greatest detail yet. All of the women were White, and only one was taking hormonal contraceptives that can cause blood clots, suggesting that was not the reason for the clots.

Tom Shimabukuro, of the vaccine safety team at the CDC, explained that the rare, severe clots were especially alarming because they were accompanied by low levels of blood cells involved in clotting - a combination virtually unheard of among healthy, young people.

"We have a picture where we have clots forming in large [blood] vessels in the presence of low platelets, so it's kind of a paradox here," Shimabukuro said. "This is unusual - it usually doesn't happen."

The combination has also been seen, rarely, among people who received vaccine developed by AstraZeneca and the University of Oxford. Four of those vaccine recipients were treated initially with heparin, an anticoagulant that is not recommended because the events closely resemble an immune-triggered reaction to the drug that could worsen the clots.

Some of the women had blood clots in other parts of their body, and Shimabukuro said the agency would cast a wider net, looking for clotting accompanied by low levels of platelets.

In a company presentation, Aran Maree, chief medical officer for Janssen, the division of Johnson & Johnson that developed the vaccine, also presented data on two cases of clots in people who received the vaccine in the clinical trial, one of whom was a 25-year-old man with a hallmark of the symptoms.

"I'd like to reiterate that, based on the current data, Johnson & Johnson believes the overall benefit-risk profile for a vaccine is positive across the population for which it is authorized," Maree said.

The blood clots are similar to those reported by several European countries after the use of AstraZeneca's coronavirus vaccine, which uses a similar technology. Several experts said it is necessary to understand whether the risks of the vaccines outweigh the benefits for certain groups of people. But they also said the risk of developing a clot after receiving the vaccine appears far lower than the chance of a clotting issue caused by a severe covid-19 infection or from using hormonal birth control, such as oral contraceptives.

The immediate practical effect of the recommended pause was limited because the overwhelming majority of the 192 million shots administered in the United States have been made by Pfizer-BioNTech and Moderna using a different technology.

Of the Johnson & Johnson doses administered to date, nearly 1.5 million have been given to women 18 to 50 years old, said Sara Oliver, a CDC medical officer and member of the committee's covid-19 work group. The Johnson & Johnson vaccine makes up fewer than 5% of the inoculations that have been administered, Oliver said.

Food and Drug Administration and CDC officials said they decided to recommend pausing the use of Johnson & Johnson's vaccine because they were worried about the possible harm if clinicians did not know how to detect, manage and treat the complication. They want to make sure medical professionals are aware that blood clots potentially associated with a vaccine should not be treated with the conventional drug heparin, which could exacerbate the clots.

Officials also want to encourage reporting from clinicians in the event there are additional cases that could help clarify the syndrome or risk factors, officials have said.

In many ways, the scenario playing out in the United States echoes what happened in Europe as rare clotting events began to be recognized in early March among younger adults, predominantly women, who had recently received the AstraZeneca vaccine.

The rare but alarming clotting cases in Europe caused some countries to suspend vaccination altogether, and scientists began to study whether the clots were connected to vaccination. A societal debate about the risk tolerance of regulators and the possible effect of vaccination suspensions on hesitancy erupted as countries halted inoculations in the middle of a pandemic. As time went on, more cases were recognized and studied.

Out of 34 million people given vaccinations in Europe, regulators there have identified 169 cases of brain blood clots and 53 cases of abdominal clots that raised suspicion.

After weeks of scientific work and meetings, European scientists and regulators concluded that the clotting events were possibly linked to the vaccine - and determined a diagnostic test and a treatment. Many countries have restricted use of the AstraZeneca-Oxford vaccine to older adults as a result.

The type of brain blood clots identified in the six U.S. cases result in a condition called cerebral venous sinus thrombosis. The normal rate of those blood clots in the general population is 2 to 14 per million people in a year. What stood out to scientists and physicians was that these clots were accompanied by very low levels of platelets, the blood cells involved in clotting. That combination of symptoms - a risk of bleeding and clotting at the same time - sounds counterintuitive but occurs in rare immune responses, when the body creates antibodies that bind to platelets, causing them to be activated and also consumed.

A similar syndrome occurs in some patients after exposure to the anticoagulant heparin, which triggered the warnings not to use that drug when treating these patients.

Since the U.S. vaccination program began Dec. 14, safety experts from the CDC vaccine advisory committee have been monitoring data weekly.

Initial information about the six cases was detected in a vaccine-monitoring system run by the CDC and the FDA. That three-decade-old system, known as the Vaccine Adverse Event Reporting System, or VAERS, is an early warning platform that also collects information about possible side effects or health problems after vaccination. It monitors unusual or unexpected patterns that require a closer look. Anyone can report a reaction or injury, including health-care providers, patients and patients' representatives, such as caregivers or attorneys.

The recommendation to pause the Johnson & Johnson rollout resulted in swift action, with the U.S. military and many states announcing they were suspending the use of the single-shot vaccine. About 7.5 million doses of Johnson & Johnson's vaccine had been administered nationwide as of Wednesday. About 16 million doses have been delivered to states and territories, and through federal channels, since the beginning of March.

 

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The Washington Post's Scott Clement contributed to this report.

Published : April 15, 2021

By : Lena H. Sun, Carolyn Y. Johnson The Washington Post