[zerof1l]

If you look at that graph, the sample size for half doze(44%) of AZ is too small: N=41 and N=62. I would not be picky over 5% difference. The trend overall looks solid to me. It's not the first time I hear that the efficacy rate of Sinovac is about 50% and the fact that Phizer and Moderna are the best options.

[rurban]

There are other studies on the effect of AZ half doses, because of the "Italian mistake" in GB, which was submitted to the European approval agency, so it became public knowledge. The sample size was over 3000, the effectiveness was over 95%.