SEATTLE — With the announcement of a pause on Johnson & Johnson COVID-19 vaccine distribution while officials with the CDC and FDA investigate a small number of rare blood clots, administration of the vaccine has been temporarily halted in Washington.
Six women out of 6.8 million people who received the vaccine in the United States developed a rare blood clot known as cerebral venous sinus thrombosis (CVST), and low levels of blood-clotting platelets. All six cases were between the ages of 18 and 48, with symptoms six to 13 days after vaccination. One woman died.
State officials announced the pause Tuesday morning "out of an abundance of caution."
Medical experts are urging people to remain calm and consider the context of this announcement, with a less than a one in 1 million probability based on known cases, and no proven causal link.
“So that’s ultimately quite rare,” said Dr. Vin Gupta, with the University of Washington Medicine Institute for Health Metrics and Evaluation (IHME). “But it’s giving us pause, and that as it should. It means the system is working, it means people are reporting side effects both mild and severe if they’re occurring. And that should give us confidence that despite the pace of development, despite everything that’s happening, we have a fully accountable system.”
The FDA and CDC are independently reviewing the data, and the CDC's Advisory Committee on Immunization Practices (ACIP) will meet Wednesday to discuss and potentially issue recommendations.
Gupta thinks it is very likely the Johnson & Johnson vaccine will be cleared for further distribution, with at most some limitations on age groups.
Interestingly, the clotting issue is similar to one being investigated with the AstraZeneca vaccine, which is being distributed in Europe but has not been approved for use in the U.S. Both vaccines rely on an "adenovirus" as a vehicle to prompt an immune response that gives the patient protection from COVID-19.
Clotting concerns led some European countries to put additional age restrictions on the AstraZeneca vaccine, a prospect Gupta believes is possible for the J&J vaccine if regulators deem it necessary.
"It's too early to say, but I suspect that ACIP will provide guidance in the next forty-eight hours to get Johnson and Johnson back up and running," Gupta said.
The Pfizer-BioNTech and Moderna vaccines rely on a different technology called mRNA to produce protection and are considered safe and effective.
Johnson & Johnson’s vaccine was a relatively small part of the rollout in Washington state, with 149,000 out of 4 million total doses. The J&J vaccine proved convenient for reaching at-risk or remote populations because it requires less refrigeration for storage and provides full protection with a single shot.
Context is also important when considering the risks versus rewards of any vaccine. The CDC lays out potential rare but serious side effects for common vaccines like DTaP and MMRV, which range from seizures to brain swelling. The agency notes any vaccine can cause side effects. But these vaccines are still widely used because the danger of the disease itself is greater, the risk of severe side effects is low, and they lead to greater community protection.
Gupta said this is important to consider with the Johnson & Johnson concern, too: coronavirus has proven deadly across all age groups, and nearly 560,000 people in the U.S. have died. As of April 13, the U.S. had 168 deaths per 100,000 COVID cases, a significantly higher risk than that of the known clotting cases being studied with the J&J vaccine.
None of the blood clotting cases are believed to be in Washington state.
“The risk of COVID-19 to the general populations across all ages, in my view, is far greater than the risk of any rare side effects from the vaccine,” said Gupta. “I think the difference here is that these vaccines, we’re just less familiar with.”
It’s also important to consider the background levels of these rare CVST clots, which impact five per 1 million people every year in the U.S. general population according to Johns Hopkins, and are more common in young people at three in 300,000. That existing level is five times higher than the current cases being investigated for a possible vaccine connection.
It’s also important to note contracting COVID-19 raises the risk of blood clots, according to the Mayo Clinic.
But the concern now is vaccine hesitancy. With some Americans already wary of the vaccine, will this public pause lead to further fears? Realistically, Gupta thinks it will in the short term, but believes long-term data will tell the whole story: that vaccines for the coronavirus are safe and effective.
“And the best way to convince people of that is just over time,” he said. “And so this will diminish in importance over time. But in the short term, this is going to be certainly an obstacle we have to deal with and talk about directly and proactively.”
There's also an argument to be made that such an announcement and pause could be premature, and undermine confidence in vaccines at large, even if the clots are found not to be related. U.S. officials have said it will not significantly slow rollout because supplies of the other vaccines are available to backfill.
Gupta adds the pause plays another important role beyond further investigation. That is giving officials a chance to educate physicians on possible symptoms, and how to treat these rare clots. Many doctors would respond to clots by giving the drug heparin, which could make things worse for those with CVST clots.
If you have received the J&J vaccine and develop a severe headache, abdominal pain, leg pain, or shortness of breath within three weeks after vaccination, contact your healthcare provider.