Oxford/AstraZeneca Covid vaccine can be up to 90% effective

British pharmaceutical giant AstraZeneca on Monday said an interim analysis of clinical trials showed its coronavirus vaccine has an average efficacy of 70% in protecting against the virus. One dosing regimen showed an effectiveness of 90% when trial participants received a half dose, followed by a full dose at least one month apart. The other showed 62% efficacy when given as two full doses at least one month apart. CNBC’s Meg Tirrell reports.