The Oxford and AstraZeneca vaccine is believed to reduce coronavirus transmission by 67%, according to a pre-publication report in the prestigious medical journal The Lancet, which reports the results of a newer clinical trial.
The same study shows that the first dose of the vaccine is 76% effective from day 22 to day 90.
This means that the protection provided by a single dose is not reduced over a period of three months.
After the second dose, the effectiveness increases to 82.4% when it is administered after three months.
In contrast, when the second dose is given less than six weeks after the first, the efficacy is 54.9%.
It is noted that the British authorities have decided to give the second dose of the vaccine after 12 weeks.
They do the same with the Pfizer vaccine. A small study from the University of Cambridge, also published on Tuesday, concluded that one dose of the vaccine was enough to produce enough antibodies in people over the age of 80 to treat the British coronavirus mutation.
However, treating the South African mutation requires two doses of the Pfizer vaccine in the elderly.