The pause in administration of the Johnson & Johnson/Janssen COVID-19 vaccine appears to be at its end. The CDC’s independent advisory panel, ACIP, voted today to once again recommend the vaccine for everyone aged 18 and over, even though there is a very small risk of blood clots in women under age 50. Vaccinations are expected to resume early next week.
What’s the new recommendation?
The new recommendation is the same as the old one: the J&J vaccine is recommended for all adults 18 and over. The FDA will include a warning about the possibility of blood clots in the vaccine information leaflet.
If you fall into the group that has been more likely to get the clots—women under age 50—you may prefer to get a different vaccine instead of the J&J, but that’s up to you. All three vaccines are still authorized and recommended for all adults, regardless of sex.
What do we know about the blood clots?
The pause, begun last week, was triggered by six cases of a rare type of blood clot. This condition that regulators are calling TTS for “thrombosis with thrombocytopenia syndrome” is an unusual combination of blood clots that may occur in the brain alongside a low platelet count. (The clots in the brain are known as cerebral venous sinus thrombosis, or CVST, but according to today’s update they can also occur in other parts of the body.) The condition is vanishingly rare in the population in general, but has occurred in a small number of people who got the J&J shot. The condition is not associated with the Pfizer or Moderna vaccines.
The symptoms of TTS begin six or more days after the vaccine, and include severe headache, leg pain, abdominal pain, and shortness of breath. (A headache in the few days following the vaccine is common as part of the vaccine response and is not a sign of TTS.) If you experience these symptoms and had the J&J vaccine in the past few weeks, go to the emergency room and make sure to let them know when you had your vaccine.
In an update given today, the number of known cases was brought up to 15, with 13 of those occurring in women age 18-49 and two in women aged 50 and over. That brings the risk, which originally appeared to be one in a million, to seven per million women in that age group. (One man had TTS in the clinical trial before the vaccine was authorized, and it’s possible that as more cases come to light, a few may turn out to be in men.)
Outside of this situation, blood clots are more common in women, and birth control pills and pregnancy are both risk factors for the more common types of clots. But among these people with TTS, only two used oral contraceptives and none had a recent pregnancy. The risk of TTS after the J&J vaccine is smaller than the risk of blood clots on birth control, and it’s also smaller than the risk of blood clots from COVID-19 itself.
One thing that is unusual about these clots is that the usual treatment for blood clots, heparin, may be dangerous to patients, and so providers should be on the lookout for the condition and be aware not to use that treatment. In the update, we learned that six of the patients were treated with heparin, but all were hospitalized before the CDC’s alert last week. After the alert, none were treated with heparin. This suggests that the effort to get the word out about TTS helped providers to make the right calls.
Why did they make this decision?
The panel spent much of the afternoon debating the pros and cons of changing recommendations. One concern was that the J&J vaccine is preferred for outreach to homeless, homebound, and migrant populations (since it’s easy to store at refrigerator temperature and since people don’t have to return for a second appointment). If the panel were to recommend the J&J vaccine only for men, that would mean that those outreach efforts wouldn’t be able to vaccinate families or couples unless they began stocking two different vaccines with different storage requirements. Here are screenshots of the pros and cons of several options that the panel discussed:
A computer model of the consequences of recommending the vaccine (or not) calculated that over the next six months, resuming vaccination would likely result in 9.8 million J&J vaccinations, causing 26 cases of TTS but preventing 1,435 deaths and 2,236 ICU admissions. That model assumed that people who can’t get J&J would not get any vaccine at all, which is probably not the case, but it gives an idea of the risks and benefits of the decision.
Ultimately, the panel faced a tough decision, but the decision for individuals is a little bit easier: All three vaccines are effective, and all three are relatively safe. TTS is still a rare condition, and we accept larger risks than seven per million for other vaccines, medications, and risks of everyday life. Still, if that’s a bigger risk than you’d like to take, seek out a vaccine from Pfizer or Moderna.