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What is Going on with the Astra-Zeneca Vaccine’s Strange Efficacy Results?
Okay, so, we have preliminary efficacy results on the Astra-Zeneca vaccine…and scientists are baffled.
You have probably seen both 70% and 90% figures circulating, and there’s a reason for that.
The trials tried two different regimens. One was two full doses of the vaccine, the other was a half dose followed by a full dose.
So, guess which one is 90% effective? Yeah, I led you with this one.
The Half Dose Works Better
In completely counterintuitive results, a much higher efficacy was obtained when the first dose was half the amount of the second one.
This virus is not a mRNA vaccine, but a viral vector vaccine. It’s made by modifying a chimp adenovirus…essentially a chimpanzee cold. (The Chinese have been using a human adenovirus as a vector, but this is generally considered more risky as prior immunity to the adenovirus could diminish the efficiency of the vaccine).
The actual results were 62% efficacy (about at the higher end of the flu shot) for the full first dose and 90% for the half first dose.
Now scientists are scrambling to work out why. Is it an artifact of the data? (if so, we’ll know and probably end up with the…