Dear @kevin ,
Great questions.
First, the majority of the vaccines that are used are prophylactic or preventative vaccines. These are basically a weakened version or fragment of the virus or bacteria. The idea is that they teach your immune system to recognise the virus or bacteria, so that when you see the real thing, you can deal with it more effectively. They stop you from being infected. Some examples are the covid vaccines, measles mumps rubella, chickenpox, etc.
The idea behind a therapeutic vaccine is similar, but instead you already have the infection. For hep b infections, much of the time your immune system doesn’t readily recognise the virus or only is partially activated. This means you get small flares, but don’t completely clear the virus. This approach presents bits of the virus to your immune system in such a way that it says “yes, you really should get rid of all cells that express this”. The hope is that this will be enough to clear the infection.
The science has been carried out by some very experienced and reputable scientists in the field, so i believe that this is a legitimate approach. The preclinical data has been promising too. I am definitely interested in the results that come out of the clinical trials.
Hope this clarifies things.
Cheers,
Thomas