You shouldn't expect side-effects this rare to show up in the trials. The AZ trial was based on ~32k participants (https://www.astrazeneca.com/media-centre/press-releases/2021...). Your probability of observing a 1/1,000,000 occurrence in 32k observations is something like 3%.
It's impossible to uncover (with statistical significance) 1/1,000,000 side effects without giving millions of doses.
The fact that a rare side-effect has (maybe!) shown up should not negatively impact your priors for how safe the vaccine is. If anything, the fact that we're talking about 7 / 7,000,000 cases should reassure you that we're catching extremely rare stuff, which means we would have caught anything more serious too.
A more general way of putting this is that, by doing a trial you don't prove there are _no_ side-effects, you just put an upper bound on how common they can be. This is the best that science can do! Epistemologically speaking, you can never prove the non-existence of something, you can just show that it doesn't occur in the places you've taken measurements, at a frequency that your experiments would detect. (This is the "black swan fallacy", as John Stuart Mill originally formulated it.)
You're right that 7 / 7,000,000 are good odds, and most people would likely take them - but it would be unwise to not give people an educated choice between vaccines if there are known risks.
They are not giving people an educated choice, they are taking that choice away until they deem it okay to give it back. Education is knowing that 7/7,000,000 had a blood clot + the other tests that were done leading up to its release. We know that now. We're educated.
The CVST incidents give a lower bound on risk. The trial data give a rough upper bound on risk (rough due to the small sample size). Knowledge is being refined here. We can't make educated choices without knowledge.
Hard to give people an educated choice without looking into the issue first. Once they know what is going on it will most likely be back to normal. There was a similar issue in Europe, but that neatly overlapped with a delivery shortage of the affected vaccine.
We should give people an educated choice. With unknown side effects we are not doing that. Thank you for pointing that out.
Make sure you cover every possible thing, no matter how unlikely.
not really. that's not how statistics work. it could grow, it could shrink.
> All six cases were in women aged between 18 and 48, with symptoms appearing six to 13 days after vaccination.
Presumably, some of the 7 million people who have gotten the vaccine did so in the prior 5-12 days. It is reasonable to expect to see more cases over the next 6-13 days from the moment we pause J&J vaccination.
And for anyone that thinks this is just normal incidence of blood clots being blamed on the vaccine - that's what was said about AstraZeneca originally, and if these clots are anything like those it is absolutely not the case. Those are serious clots that are very rare to see period, let alone in young people, and require different treatment than normal clots (they have surprisingly low platelet count).
I suspect US agencies had good reason to want to pause J&J given all of that - the AZ vaccine issues were also disproportionately affecting women interestingly.
I suspect that, as soon as we start looking for blood clotting post-vaccine, then you'll find more cases that may have not been caught otherwise due to their not being severe enough to be noticed.
https://twitter.com/HamidMerchant/status/1381797044495466504
If that is the case we could then target this vaccine to the rest and have it be much safer while giving out the Pfizer-BioNTech or Moderna vaccines to this group.
End result is everyone still getting their vaccine fast but less side effects (and possibly deaths due to worst case side effects). This is why we need more data or the time to study the data in this case most likely
Don't know if it matters to anyone, but the "FDA has suggested that health care providers pause the use of the vaccine while the side effects are being studied. However, providers are not prohibited from using the vaccine if they feel the benefits to an individual patient outweigh the risks." [1]
1. https://www.npr.org/sections/health-shots/2021/04/13/9867670...
Well, obviously it didn't. Exactly because it is so rare
A clinical study with (I think) 30k people can't detect something that's 1 in a million case
> FDA bureaucrats
You mean doctors. These decisions are done by doctors as they should be. The current (acting) head of FDA is a physician too.
It's not clear that this even has to do with the vaccine. If you gave 7 Million people a glass of water on the same day, I'm sure at least 7 of them would experience some sort of moderate to serious health outcome in the days that followed.
It is a two sided equation.
Not sure why the J&J vaccine had to pause for older population where clearly the vaccine has a much better benefit/risk profile though. But at least in my area of the US the vaccination rate for senior citizens is quite high already.
To be clear, we haven't determined that it's actually a side effect. That's why they've stopped, to get a better handle on what actually happened, and what to do about it.
It could be related to the vaccine, it could not be. It could be 1 in a million, it could be 1 in 100k.
We have approved vaccines with worse side effects before. The difference is that we knew what those side effects were and weighed the risk vs reward and made the call to use it.