That is speculative and based on zero data. Yes this is just a population correlation with a 98% vaccine rate population but it's just a data point. If you want to conclusively prove it you could do a study and inquire into the vaccination status of the diseased. You could also do a study to conclusively prove if the vaccine stops you from getting the disease, spreading the disease, being hospitalized of the disease or dying of the disease. For some reason nobody wants to spend the money to do these studies. So we just have the data points we have with the population correlation that suggests but does not conclusively prove anything. Just like it isn't proven that the vaccine stops you from getting the disease, spreading of the disease, being hospitalized from the disease or dying of the disease.