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Comment by JamisonM | Hacker News Reader

AZ has already said they are waiting until their new US-based trail finishes before even applying. They haven't finished recruiting, 28 days between shots, then (I think) 75 infections in the participants before they will report interim data.

It is going to be quite a while.

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I'm also in the AZ study and just spoke to the head doctor of my testing site Friday. They've finished recruitment and likely will have enough cases by the end of this month. BUT...the FDA said they won't consider an EUA until they have at least 2 months of safety data from half the participants. Given that restriction, he expects them to not be able to apply for an EUA until April.

Seems a bit unnecessary to wait for the US data when they could use the same data the UK used, plus we've now given the vaccine to several million.

The AZ data is often considered to be somewhat dodgy, e.g. with dosages mixed up, patient groups selectively joined or split up for p-hacking purposes, etc. I can understand the US wanting a proper study under their own oversight.

I think dodgy is overstating it a bit. It's clear from the data in multiple trials and post-rollout studies that AZ vaccine is very safe and somewhat to very effective. There is a lack of gold-standard double-blind trial data to nail down answers to specific questions about efficacy, but given current overwhelming evidence of saftey and the raging pandemic it's entirely reasonable for e.g. MHRA to approve rollout.

The main question that seems to remain is effectiveness in over 65s. Essentially not enough older people became sick in either arm of the trials (e.g. due to lockdown) to make any conclusion. However there is definitely indirect data (antibody titres) to infer that efficacy is not reduced in older population.

What do you think the chances are that it's unsafe?

I think the chances that it is unsafe are zero. Someone in the UK would have noticed by now, they vaccinated quite a lot of people.

The interesting question that needs to be answered is: to what degree does it work, and for which groups? Of course it would be possible to just widely distribute the vaccine (since I consider it safe) and run the study to answer that question in parallel. In the worst case, you widely distributed an expensive placebo. Don't know if that is a good idea overall however.

In my mind the worst case is we hold off on distributing it for a couple of months. And later find out that it was far more effective at preventing death/hospitalization than symptoms. So we end up 1,000 more dead than we would have if we vaccinated with the AZ vaccine.

I guess the problem with rolling out ineffective vaccines is if you waited a little you might have got a better one. Guess it depends a bit on how long it'll take to crank up the others.

Given the low confidence intervals due to the small study size (~10,000) in the overseas studies, I don't think the FDA is wrong to wait for enough events (aka X people get COVID) in the USA study to more accurately determine effectiveness (30,000 participants, 2/3 with vaccine). That said, I think it's likely safer to consider safety data from those other studies, as that's unlikely to change much based on study size (especially combined with the fact that X million have been distributed overseas).

They have finished recruiting. I believe towards the end of January.

Finishes?! I was told the study completes in 2 years...

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