That’s study says “Immunity elicited by direct vaccination or by maternal vaccination prolongs host survival but does not prevent infection, viral replication or transmission, thus extending the infectious periods of strains otherwise too lethal to persist.”

Is this your concern with the covid vaccine? That a strain which would have killed someone unvaccinated, that person will now instead stay alive and spread it?

The viruses used and discussed in that study had between a 60% and 100% fatality rate. This is pretty different than covid 19