The vaccines have undoubtedly saved tens, perhaps hundreds, of thousands of lives worldwide. No amount of "building your immune system" could possibly achieve such a thing!
The function of your immune system has far more to do with your genetics than it has to do with anything you have any control over. That isn't to say that you can't help things along by eating right, exercising and getting proper sleep but, in all but the rarest of cases, the effects we can have on automatic biological functions in our body like the immune system is rather marginal. Even factors such as body weight and how well one's body handles sugar has at least as much to do with your genetics than it has to do with the choices you make in your daily life.
And even if none of that were true - it is true but even if we reject or ignore it totally - even with the massive lifestyle changes - that almost no one is going to make - the effects of those changes would take months and months to manifest and even then it wouldn't make even 1% of the difference that an effective and widely utilized vaccine makes almost immediately.
In short, the sentence "Far Better To BUILD Your Immune System Rather than Count on Vaccines to Protect You!" is not only ignorant but is dangerously stupid.
Clete