How are they establishing effectiveness?
The only trustworthy method of establishing effectiveness is to challenge vaccinates with field virus and show that subjects who had the vaccine were protected and controls who were unvaccinated went down with the disease.
Ethically, you cannot do trials like this with serious, potentially fatal diseases.
So, either the disease is benign and risk free, or they are using antibody titres to measure effectiveness. Where is the proof that the antibody response is protective?