Nothing much has changed since last years Israeli study, just what is studied. That study focused on effectiveness of the vaccine as it was administered. Lately that sort of study is getting almost impossible to quantify as those that are not vaccinated all have some form of antigens due to Covid being so wide spread. In Europe especially most people have had some exposure to covid now, so a high proportion have antibodies. That in no way infers immunity, as its the amount of circulating antigens that determines whether you get infected or not. Which is why Germany does not accept antigen tests as a form of pass.
The 3rd jab has been happening in Israel for a number of months now, it is not an extra jab to the initial 2. It is a booster shot that will be required regularly as antigen density drops off and therefore immunity wanes. One would assume there will be a 4th, 5th and 6th jab as long as Covid is prolific in the community.