Yes, the clinical definition of thrombocytopenia is low platelets. Like many clinical definitions, it says nothing about the cause of the condition, and I'm sure that's what the FDA and J&J want to investigate. I wouldn't pretend to want to give advice on how to deal with patients, but I will says this: adenovirus vectors are very common in the world. They cause colds, and they've been used to develop other vaccines. So I doubt that it's the AAV causing this problem. It is probably more likely that the spike protein antigen is stimulating the immune system in a similar way that the covid virus does, as clotting is an all too common complication of covid--it's one of the main drivers of the cardiovascular issues that have affected so many people. So for me, I wouldn't want to scare anyone off of AAVs generally. All that said, I'm also not going to pretend to understand something I inherently don't. Just reading up on the other AAV vaccines that have been studies over the years, it looks like they don't generally see the side effect profile that the J&J vaccine evokes. So there's clearly something weird here. Our bodies, as you know first hand, really hate this spike protein. I think the prudent thing here is to remember we're talking about 6 serious adverse events and 1 death out of about 7 million total doses given. I don't know the proportion of women from 20-50 in that cohort, but let's say it's 20% for argument's sake, which would mean we're talking about 6 out of 1.5 million, or about 1/250,000. If you're a betting man you take those odds. If you're a pregnant patient, maybe you just wait for the RNA vaccines to become available to you.
Adenovirus vectors may be common, but adenovirus vector vaccines are not. That's what killed Jesse Gelsinger back in '99, which basically stopped recombinant DNA therapy stone cold in its tracks for fifteen years. Adenovirus vector vaccines were tried against ebola in 2014 and 2015 but they're still pending approval while the mRNA vaccine kicked up in the wake of the 2014 outbreak has already been approved. This is what bit genentech and the rest in the ass in 1999: adenoviruses are everywhere so adenoviruses should be no problem. But they have been in the past. My buddy Dr. Strangelove actually did his thesis on replacing adenoviruses with ebola for gene therapy so no wonder he ended up at Ft. Detrick. I have my suspicions that neither the AstraZeneca nor the J&J would have been approved so quickly if we weren't under emergency conditions, which also increases my concern - if these are the side effects we're catching now, what side effects aren't we catching a year from now? I agree - vanishingly small percentage impacted, much higher stakes, but we might end up saying "you'll almost certainly be fine, we happen to know your platelet count, but if you're totally freaked out we'll write you a note to try and increase your chances of getting the Pfizer or Moderna" as if it'll actually do anything. We've definitely got more anti-maskers among our clients than we do those with chronically low platelets, and we've been gleefully pointing out that "pregnancy" has been a "preexisting condition" warranting cutting the line for the past couple months.
As I understand it the Ebola vaccines haven't elicited much in the way of terrible side effects, but the trouble is that they've been given to thousands, not millions of patients. I think it's weaker efficacy, and not safety that have held up their approvals. Clearly with an ultra rare complication such as this one, it takes a hell of a lot of subjects to see a signal. Again, if it were me, I'd take the vaccine without hesitancy. We should expect the adverse even rate to decrease, not increase a year from now, because the AAV is not replication competent. Only time will tell though. This whole saga only seems to get stranger with time.