https://www.cdc.gov/vaccines/acip/meetings/slides-2021-04.html
ACIP didn't make a recommendation on J&J yesterday, but some useful background information was presented to contextualize things a bit more on the risks and costs.
While 7.2 million doses of J&J were administered, only 1,495,400 doses were given to women between 18-50, where six cases of the CVST with thrombocytopenia occurred. According to ACIP, about 0.39 to 1.58 cases should have been seen in this group normally. So this is above base rate by 4-15x.
3.8 million doses of J&J were given from March 30th to April 13th, so they are still in the period where this side effect can surface (~6-13 days).
These cases didn't just have CVST, but also presented with thrombocytopenia, had elevated D-dimer, and were PF4 positive, which matches the presentation of the AZ vaccine related incidents.
All of the women presented with headaches. All that were tested were PF4 positive. Only one woman was on hormone medication.
A 25 year old man from the phase III trial had CVST that was anti-PF4 positive. And subsequently a 59 year old woman as well. So it is likely more cases will follow and like the AZ vaccine this won't be just in young women.
There have been no CVST with thrombocytopenia cases with Moderna or Pfizer's vaccines.
As far as supply affected, 13 million doses of J&J were ready to be used. However, Moderna and Pfizer supply is sufficient.
It sounds like they are still waiting for more information on cases before they advise on whether to restrict the vaccine for certain ages and sexes.
So what's causing this?
One of the initial studies proposed that free DNA from the Adenovirus vector breaking apart is binding to the PF4 antibodies and causing the reaction.
Though only a theory at this point.
That same study largely ruled out that the spike protein was to blame which was another preliminary theory. And also ruled out Covid infection as a cause.
So far we haven't seen the phenomenon of VITT in the mRNA vaccines of thrombosis with thrombocytopenia, so that lends some support to the theory that it is the Adenovirus vector at fault.
We haven't really given Adenovirus vector vaccines to this level of people this quickly before, so it could be we just never saw it. The other major vaccine that uses Adenovirus vectors is an Ebola vaccine that hasn't been used that much.
J&J has really banked on Ad26 Adenovirus vector as a tech for a bunch of viruses, so this could be a blow to them.