All of this is built upon the premise that the vaccines are effective in the short-term and will remain effective. That premise is almost certainly not true.
The third booster shot only improved efficacy from around 35% to around 70%. In other words, it only achieved a 50% gain, compared to the 95% gain from the initial series, and that gain drops off rapidly. That should be a huge warning, and that's the companies' own data showing it... not some crackpot anti-vaxxer. Yet we're jumping ahead to dose number four in some countries, of a vaccine that hasn't been reformulated to current strains.
I'm thinking that trusting a for-profit pharmaceutical company to formulate a vaccine, for which they profit more the more doses that are given, might have been a bad idea. I hate to say it, but this vaccine program should have been nationalized under the Defense Production Act.