- An advisory panel to the Centers for Disease Control and Prevention supported continuing the pause in vaccinations with Johnson & Johnson's coronavirus shot, agreeing at a public meeting Wednesday to wait for more data related to the rare blood clotting events that were reported earlier this week.
- On Tuesday, the CDC and the Food and Drug Administration recommended halting use of J&J's vaccine, citing the apparent side effect, which has led to the death of one woman and the hospitalization of five more. While exceedingly uncommon — nearly 7 million people in the U.S. have been vaccinated to date with the shot — the rate is at least three times higher than what would be expected in women between the ages of 20 and 50, a CDC official said.
- Large clinical trials like the one J&J ran to secure emergency clearance of its vaccine can readily identify more common side effects. But rarer complications may only come to light after millions of people have been vaccinated, as is the case with J&J's shot now. Assessing newly identified risks with limited data can be challenging, and on Wednesday CDC advisers grappled with balancing their concerns against the ongoing health threat from COVID-19.
Opting against a formal vote, the Advisory Committee on Immunization Practices asked CDC officials to return with a more complete data set within seven to 10 days to help it make a recommendation on safely resuming use of J&J's vaccine.
Their recommendation could take the form of age- or gender-based restrictions, or rely on other risk factors that might be identified in the coming days as the CDC and the FDA continue their investigation into the serious side effect.
The J&J vaccine is the second one linked to unusual and dangerous blood clotting near the brain. Somewhat counterintuitively, the clots have occurred alongside low levels of platelets, the sticky cells that help blood coagulate.
More than 200 people vaccinated in Europe with a shot developed by AstraZeneca have experienced a similar pattern of symptoms, leading many countries to suspend use. Some, like the U.K., have since resumed vaccinations with age-related restrictions.
At Wednesday's meeting, many of the CDC advisers didn't believe they had enough information about specific risk factors that might help define who can still safely receive J&J's vaccine. While the abnormal blood clotting has been seen primarily in women aged 18 to 48, there was one case in a man enrolled in J&J's clinical trial.
The concern over the cases relates specifically to clots blocking one of the veins that drains blood from the brain. Usually, such cases aren't accompanied by lowered platelet levels, as is happening in these vaccine-linked cases, and the CDC hasn't been able to establish how often both occur side-by-side in the general population. Officials, therefore, couldn't say precisely how the rate in vaccine recipients compares to what would be expected normally.
Moreover, onset of the clotting appears to occur between six to 13 days after vaccination. As more than half of the 7 million total J&J vaccinations have taken place in the last two weeks, more cases could emerge in coming days, which would push the incidence rate higher.
Imposing a gender-based restriction would be difficult to implement, CDC officials said. Meanwhile, there isn't enough data to indicate a safe cut-off by age, according to CDC.
"I just don't feel that was enough information to make an evidence-based decision," said Beth Bell, a professor at the University of Washington School of Public Health.
Meanwhile, the wide availability of vaccines from Moderna and Pfizer reduced the urgency committee members felt to resume use of the J&J vaccine without properly assessing the safety risks.
But some advisers noted J&J vaccine's one-shot regimen makes it a better choice for vulnerable individuals who might not be able to easily access both doses of the Moderna and Pfizer vaccines.
"Putting this vaccine on pause for those of us who are frontline healthcare workers has really been devastating," said Camille Kotton, associate professor at Harvard Medical School.
"We were planning on using this vaccine in the state of Massachusetts for people who are homebound and otherwise not able to get a vaccine," Kotton added. "We were planning on using it for our vulnerable inpatient population, often with many comorbidities and at high risk for disease but who haven't been able to get vaccinated otherwise."
Several committee members echoed her concerns, and advocated for a swift decision on new guidance even if data remain incomplete in the coming days or week.
"An indefinite pause is functionally a decision and I would not advocate that because that is not a decision I think makes the most sense," said Grace Lee, an ACIP member and professor of pediatrics at Stanford University School of Medicine in California.