Data gap threatens to complicate Johnson & Johnson vaccine pause

It could take two weeks or longer for federal health agencies to gather and analyze enough data to determine conclusively whether there is a link between Johnson & Johnson’s coronavirus vaccine and reports of rare but severe blood clots in recipients, according to two senior administration health officials.

Federal officials called for a nationwide pause in the shot Tuesday, predicting then it might last only a few days. The current investigation is already intensifying concerns by state officials that the public will lose overall confidence in Covid-19 vaccines.

The data gap may not be fully resolved by next Friday, when the Centers for Disease Control and Prevention’s vaccine advisory panel is set to gather for the second time to discuss the concerns about the shot, the two senior health officials told POLITICO. Federal health agencies have said they will look to the panel for guidance on how to move forward; one likely scenario is that the panel, and Biden officials, will decide to issue a stronger warning next week about potential risks or restrict eligibility while pledging to continue studying the matter.

"They're going to go back and do a model. How many people in a cohort of women of that age, within two weeks of any particular time, had this happen? And that's going to be the causality," a third senior administration official said. "So let's say they get two or three more cases. It's going to then be be 9 cases out of 6 million. The incidence is going to be so low... they may say one of two things, we're going to allow it, but we're going to allow it for people younger than a certain age and they may or may not restrict based on gender. They really can't wait too much past [next] Friday."

That still leaves the CDC’s disease detectives facing a massive logistical challenge. Roughly 7 million Americans have received the J&J vaccine, and six women ages 18-48 are known to have developed clots; one died. But federal officials believe that an unknown number of past cases might have been overlooked — and the only way to find them is to appeal to doctors nationwide to report any patients whose blood clots, in hindsight, might have been linked to the vaccine. The CDC is also on the lookout for any cases that might emerge among people vaccinated in the last few weeks.

CDC officials are working with Johnson & Johnson to interview doctors and patients involved in the known cases — seeking more detail on the treatment they received, their underlying health conditions and the medications they take, which could reveal patterns linking the clots to the vaccine. The three senior officials who spoke to POLITICO said they hope the CDC advisory panel makes a determination about the pause next week, and that they will continue updating its members on a rolling basis as they receive more information about cases.

Yet that effort has not lessened the immense pressure on the Biden administration to find a way forward — quickly. The administration has for months worked to reduce vaccine hesitancy nationwide and any prolonged pause in use of the Johnson & Johnson shot could undermine that effort. Frustration is also growing among governors who say the J&J vaccine — the only one-shot option available in the U.S. — is crucial for inoculating vulnerable groups like the people experiencing homelessness, homebound seniors and prisoners.

“The longer the pause is, the longer it's going to take for us to convince people that this particular vaccine is safe again,” Arkansas Gov. Asa Hutchinson, a Republican, told POLITICO.

Already, conspiracy theorists and anti-vaccine proponents are using the Johnson & Johnson setback to fuel hesitancy and mistrust through social media.

“It’s a setback — no question about it,” said Peter Hotez, a vaccine expert at Baylor College of Medicine. “When you have this kind of anti-vaccine aggression out there, it changes the equation. This will be exploited.”

The White House did not respond to a request for comment. HHS did not comment on the record for this story.

Federal officials have said they called for a pause, rather than just issuing a warning to the public and clinicians, because of unusual aspects of the clots now under investigation. Known as cerebral venous sinus thromboses, they develop in blood vessels leading to the brain. Several of the women who developed the condition after vaccination also had low levels of platelets, which help form clots. Health experts believe the strange pairing could be the byproduct of an immune reaction to the vaccine.

The fact that the pairing can be worsened by the blood thinner heparin was of particular concern to Biden administration officials, because the drug is a standard treatment for most types of blood clots.

The six known cases were reported to J&J directly or to the CDC through its Vaccine Adverse Event Reporting System (VAERS), which relies on health care providers to flag when an individual experiences a reaction to any vaccine.

Federal officials are now urging doctors to report any cases that have so far flown under their radar to guide both the CDC vaccine advisory panel’s recommendations and a separate but parallel probe by the FDA, which authorized the J&J vaccine in March.

But while they gather data, concerns are growing over what effect the pause will have on people’s willingness to be vaccinated and the nation’s ability to tamp down the current surge in new Covid-19 cases.

“This hold on [the J&J vaccine], however temporary, is still a setback,” said Archana Chatterjee, dean of Rosalind Franklin University’s Chicago Medical School and member of the FDA’s vaccine advisory committee.

U.S. officials could follow the lead of European countries that have limited use of AstraZeneca’s vaccine to older populations over similar concerns about rare blood clots. The AstraZeneca vaccine uses the same adenovirus technology as Johnson & Johnson. But Chatterjee said there is not yet enough available data on the J&J shot to draw conclusions about clot risk. “That is what we have to wait for, and I know people are impatient about it,” she said.

In the interim, the Biden administration could take various steps to alert and educate Americans about the blood clotting issue post-vaccination. They range from issuing a general warning about the possible side effects to restricting eligibility for certain portions of the population, even if temporarily.

The Food and Drug Administration could also revise its emergency use authorization for the Johnson & Johnson vaccine to require a warning or narrow the groups for which the vaccine can be used — perhaps by barring its use in women of child-bearing age. But doing so would likely involve weeks of reviewing data and possibly even reconvening its own expert vaccine advisory panel in a bid for transparency.

While the United States has secured enough doses of vaccines from Pfizer and Moderna to vaccinate its entire adult population, states have been counting on the logistical advantages of Johnson & Johnson’s single shot to reach vulnerable populations who might be harder to vaccinate using two-dose options.

The vaccine “had become a really important tool for equity outreach,” said Jeffrey Kahn, a bioethicist at Johns Hopkins University. “The one-dose regimen, and handling, made it really helpful for getting to populations and communities where a two-dose regimen was impractical, or impossible.”

Richard Jermyn, a physician and instructor at Rowan Medicine who is spearheading vaccination clinics for the homeless and other at-risk groups across southern New Jersey, said the announcement last Tuesday of the J&J pause forced him to cancel around 320 appointments for migrant farmworkers who had been scheduled for later that day at a pop-up site in Bellmawr. The state health department offered him use of Moderna vaccines starting early next week but, given the transient populations served by his clinics, he put slim odds on the likelihood of many patients returning for their second dose.

Baltimore, Maryland’s Health Care for the Homeless decided last week to switch entirely to Johnson & Johnson’s vaccine to immunize thousands of people in the city area, just days before the pause was announced.

The organization — which can receive doses from both the state and federal allotments because it is a federally qualified health center — was able to quickly switch back to Moderna shots during the J&J confusion. But the group is not clear what its supply will be down the line. Health Care for the Homeless vaccinates roughly 300 people a week, but there are at least 10,000 people experiencing homelessness in the area. The group won’t use Pfizer’s vaccine because it requires freezers that make it impractical for mobile vans.

“There were lots of advantages to the J&J vaccine,” said Health Care for the Homeless CEO Kevin Lindamood. “It would double our impact.”

Sam Sutton contributed to this report.