Magazine date:
Dec 2020 
The covid-19 vaccine developed by Oxford-AstraZeneca would be more effective with a smaller injected dose. Scientists have mixed views on this finding, but the data show different rates of effectiveness depending on the doses administered to patients.
According to AstraZeneca's press release, the efficacy rate of its vaccine is 70%. This rate is an average of two results, one obtained following the injection of half a dose of the Covid-19 vaccine (90% efficacy) and the other following the first injection of a full dose of the vaccine (62% efficacy).
A survey is being conducted to better understand this phenomenon.