News > Explained: Will Covid-19 vaccines protect us? Does efficacy equal effectiveness?

Explained: Will Covid-19 vaccines protect us? Does efficacy equal effectiveness?

If a vaccine has an efficacy of, say, 80%, it means that if 100 people who have not previously been infected by the coronavirus are given the vaccine, on average 80 of them will not get the disease that the virus causes: Even with 95% efficacy, there is no absolute guarantee of protection for any particular individual.

Will these vaccines stop the coronavirus pandemic? Experts say this is unlikely.