Oxford-AstraZeneca Efficacy Improves If Second Shot Delayed

In preprint paper, Oxford University and AstraZeneca published that delaying the second dose of their vaccine beyond four weeks shows an increase in the efficacy results. 

The data in the preprint show that vaccine efficacy was high when the interval between the two doses was two months and continued to increase with a longer dose interval. Vaccine efficacy after two standard doses increased from 54.9% when the second dose was administered less than six weeks after the first dose to 82.4% when the gap between the two doses was more than 12 weeks.