AstraZeneca's Covid-19 vaccine averages 70% efficacy

Pharmaceutical giant AstraZeneca announced Monday that its Covid-19 vaccine has shown an average efficacy of 70% in large-scale trials. When given as a half dose followed by a full dose a month later, it showed 90% efficacy and with two full doses given a month apart, it showed 62% efficacy.

"What we've always tried to do with a vaccine is fool the immune system into thinking that there's a dangerous infection there that it needs to respond to -- but doing it in a very safe way. So we get the immune response and we get the immune memory ... waiting and ready if the pathogen itself is then encountered," so Professor Andrew Pollard, the trial's lead investigator at Oxford.