That's not strictly accurate as it seems to depend on how the dose is administered - a half dose followed by a full dose is showing 90% efficacy.
A coronavirus vaccine developed in the UK can prevent 70.4% of people from getting Covid-19 and up to 90% if a lower dose is used, according to data.
Oxford University said interim analysis from its phase 3 vaccine trial showed that the efficacy of their vaccine is 70%. But that came from combining the results of two different dosing regimes, one of which was 90% and the other was 62%. The 90% regime involved a half-dose first and then a full dose of the vaccine later.
https://www.theguardian.com/society...-70-per-cent-efficacy-covid-oxford-university
Either way, it's 70% more protection than we have at the moment, so I would be inclined to take it if available.