Exactly, the jab promotes an immune response which will help teach the body how to deal with the virus if (or more likely when) you get infected again. It's not injecting antibodies.
A jab within a few days of an active infection is not going to promote as much of an extra immune response, so it would effectively be wasted. Conversely, waiting a year after an active infection is waiting too long, so the cut off that has been decided on looks like it is 28 days.
Exactly, the jab promotes an immune response which will help teach the body how to deal with the virus if (or more likely when) you get infected again. It's not injecting antibodies.
A jab within a few days of an active infection is not going to promote as much of an extra immune response, so it would effectively be wasted. Conversely, waiting a year after an active infection is waiting too long, so the cut off that has been decided on looks like it is 28 days.