If they come out with a Covid vaccine, how effective will it be?

Well this is a whole issue isn't it.. how safe is any vaccine? Many will tell you they are all completely safe, there is science to question that however.. Re the COVID vaccine, at present none have been adequately tested and none will have identified any long term risk.. So I wouldn't! And that's without even touching the debate re how effective they are.. there's a fair bit of evidence to question how effective normal vaccines are..