Johnson & Johnson vaccine’s fate to be decided today
Question: What do we know about what’s causing the side effects?
The fate of Johnson & Johnson’s one-shot vaccine will be decided today when a U.S. Centers for Disease Control and Prevention committee meets to review whether there’s enough data to say whether it is safe to resume its use.
Options include a full resumption, restrictions by age or gender — or extending the current pause, which would cast a shadow over its safety.
The vaccine promised to be a game changer for hard-to-reach communities, from the isolated ranch towns of the eastern Sierra to the homeless shelters of San Francisco. But its distribution was paused after the federal government received reports of six cases of a rare health problem — severe stroke-like blood clots, accompanied by low platelet counts — among the 6.8 million people who have received the Johnson & Johnson vaccine. A similar reaction was seen in Europe’s AstraZeneca vaccine, which uses a similar approach.
The risk of this side effect is 0.008% — lower than your risk of getting hit by lightning on your drive to the injection site, said Dr. John Swartzberg, a UC Berkeley infectious disease expert.
“It would be unfortunate if people delay getting vaccinated because they don’t want to get the J&J vaccine, then get sick with COVID, which is a far greater risk,” he said.
In the 10 days since the vaccine was shelved, experts have been poring over data in search of a confirmed link between the vaccine and the blood clotting disorder. They’ve reached out
to alert every health department and physician in America. And they’re racing to understand the underlying problem.
Meanwhile, European countries are preparing to resume its use after the European Union’s drug regulator this week endorsed the shot. Several nations are expected to impose age restrictions.
While Friday’s recommendations by the CDC’s Advisory Committee on Immunization Practices aren’t binding, they will guide the practices of state and local health departments, as well as individual doctors.
We asked local experts to explain the process. Q All those J&J vaccines are sitting in storage while people get sick from COVID-19. Why did the advisory committee need 10 days? A The biggest thing that’s been going on is … waiting. The ACIP needed more data. And the only way they could get more data was to get more time. It appears to take one to three weeks, after getting a vaccine, for blood clots to occur. But about half of all the J&J doses were given within the previous two weeks of ACIP’s first meeting. So they needed at least another week of data.
They needed to see whether there were going to be many more cases coming out over the next week. They didn’t want to be surprised by a whole boatload of new cases.
They’re also notifying the medical community about the clinical presentation of this disorder — that is, what it looks like. And how to treat — or how not to treat — a patient, and how to report a case. They needed to make sure that all the public health departments in all the states and counties have protocols in place. — John Swartzberg, M.D.
Q What kind of data are experts looking for? A It’s important to know the frequency of this rare clotting disorder in the general population
— so we know whether there’s a link to the vaccine. We don’t have that data.
It’s possible that this disorder has nothing to do with the vaccine, and it’s just a coincidence. Perhaps we were paying very close attention to the safety of these vaccines, so the association got made.
To develop the data, one approach is to dig retrospectively into the literature and see how many case reports are out there
— then try to make some kind of estimate about the likely range of cases in people who aren’t vaccinated.
Another approach is to see whether any of this is happening with the mRNA vaccines from Pfizer and Moderna. That’s our “control group.” — Joel Ernst, M.D., professor of medicine and chief of the Division of Experimental Medicine, UC San Francisco
Q What alerted the CDC to the problem?
A The event that caught people’s attention was the somewhat atypical presentation of a low platelet count and a blood clot, along with the unusual location of the clots. Most blood clots are in people’s legs. In these cases, they were in veins of the head. That’s a much more rare location.
It was this aggregate finding of low platelets and clots in funny locations and the similarity to the AstraZeneca cases outside the U.S.
This strange aggregate of clots in unusual locations with low platelets has been described in a couple of other situations in medicine — and one of them relates to a problem called heparin-induced thrombocytopenia (HIT).
But these people didn’t get heparin. — Andrew Leavitt, M.D., director of UCSF’s program for noncancerous blood disorders
Q Are there theories about its cause?
A There is this hypothesis that there are other negatively charged molecules, like heparin, that may trigger this problem. So the clinicians performed tests, looking for the kind of autoantibodies that people form when they have HIT. And these people had them — antibodies to a protein called Platelet Factor 4.
The big question is: What is the negatively charged molecule that is interacting with Platelet Factor 4 and allowing for the new antibodies to be generated? Is it part of the patient’s immune response? Is it something in the vaccine itself? Nobody knows, but that is obviously a key focus of investigation. — Andrew Leavitt, M.D.
Q Why would your body make these antibodies?
A It’s because the immune system isn’t always perfectly regulated, and it makes antibodies
against things that it shouldn’t. That may be what is going on here.
And a test for those antibodies is not widely available. It’s pretty specialized. It’s not something that a practicing physician can just send off a tube of blood to a lab and get the answer back in a day or two.
And the cost of testing is very likely going to exceed the cost of the vaccines. If the frequency is one in a million, it’s taking resources away from other more likely problems. — Joel Ernst, M.D.
Q What can we learn from these patients? A Understanding the mechanism that triggers the response to the vaccine is tremendously important from the diagnostic and therapeutic standpoint. But it is less urgent than trying to understand the common patterns.
For example, being a male might put you at less risk. Or being a menopausal female. There might be commonalities about certain medications that people were taking. Or certain underlying diseases.