Is There a Difference Between Efficacy and Effectiveness?

There's a technical difference between efficacy and effectiveness. There is good efficacy in older people, which would imply that there is good protection as well. We've had an anonymous listener who doesn't want to be identified,. She has had her vaccination, but when the syringe came out of her arm, she started bleeding. What do you think, thinking about this? Anthea: Do people have serious concerns? I mean, we always talk about vaccine hesitancy, but actually huge numbers of people have been vacinated.