What makes you say that?
You have to have 2 doses for the vaccines to be fully effective, all they have discussed is stretching the period between the two jabs to 3 months instead of 3 weeks.
This has also been approved by the WHO for emergency situations, e.g. where demand is outstripping supply.
Unfortunately the gov ministers don't seem to be singing from the same song sheet. Hancock says by the end of June but Raab comes up and says probably not until the end of September. (interview today on Sky news) Even talking about stretching it out longer than 12 weeks to make sure everyone gets at least one dose which is causing a bit of angst among virologists.
To vaccinate that many people in the 9 months Raab is talking about will still be an incredible achievement, Doubt if anything like it has been done before and more power to their elbow. Just the members of the same government who keep coming out with conflicting statements.