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Comment by BillyTheKing | Hacker News Reader

the just tried to fit in numerous trials into a single trial, whereas Biontech/Pfizer and Moderna were super clear about their trial-architecture and data (same 2-dose regime, given 3 weeks apart), we seem to have a ton of small trials with different data for that Oxford/AZ vaccine. Those 1300 participants who got the half dose full dose vaccine also turned out to be significantly younger than the other group who got the two full-dose regime, making those two groups really difficult to compare (apart from the fact that they were also differing in size)

Now we have a new number out there, 90% if the two doses are given 3 months apart, does anyone here now what the trial-size was? the age distribution? The statistical significance for that finding?

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Don't forget that the BioNTech/moderna trials weren't really comparable - they relied on self-reported symptoms to trigger checks for infection. That is likely to lead to a higher apparent efficacy at the same underlyng efficacy.

By now it's clear that for all three vaccines regardless of the exact efficacy of the vaccine, the chances of getting a severe case is greatly diminished. It's at least plausible that getting a vaccine reducings the severity of an infection in general; specifically that it might push what would otherwise have been a mild case into the asymptomatic (but infected) category. I don't know how large that group is, but given how many mild cases there are, it could be quite sizable. And those cases would not have been included in moderna and biontech/pfizer's efficacy numbers, but would have been included in the oxford/AZ trial's numbers.

So while I'm no expert in any of this, I think it's at least fair to say that it's not trivial to compare the efficacies reported from the two mRNA vaccines to that of the oxford/AZ vaccine, because of this difference in methodology. Including vs. mostly excluding asymptomatic cases will affect the numbers.

The point being? All of these trials have their limitations; the oxford/AZ trials may have had bumps (but nothing all that serious sounding), but they also have extra data in the form of asymptomatic cases. The comparison isn't straightforward.

that 62% number is for symptomatic cases, I think it was around 50% for asymptomatic cases - the different efficacy-rates are fairly comparable

That is a good point, I'd forgotten that bit ;-).

(ref: https://www.thelancet.com/journals/lancet/article/PIIS0140-6... vs. e.g. https://www.nejm.org/doi/full/10.1056/NEJMoa2034577 )

From the news report it's 95%, not 90%. Presumably the data about sample size etc. will be available when they publish. You can't reasonably expect that level of detail from a news article reporting prior to publication.

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