#69242
Those who have never contracted the disease do not have active antibodies for it, but that does not mean he has no immunity against it. Totally absurd conclusion on the part of his trainer. If he has no immunity, then he has no immune system and I find that unlikely if he's walking around on this planet.
I also find it unlikely that he was never exposed to it in all his 27 years. As such, his immune system has been strong enough to repel contraction all these years without injection and there's a good bet it will continue to do so.
The worst thing he could do is voluntarily vaccinate himself, thereby exposing himself to the virus undefended where there's a better chance he'd get it than doing nothing. At the same, time he'd be weakening his naturally strong immune system and thus increasing his chances of contracting other infectious diseases later in life, as well as passing on this weakness to his potential offspring.
I know how tough it can be getting it as an adult (I had it 19), but if he's going to get it, the best way to get it is still by natural means whereby a lifelong immunity is rewarded. Synthesized immunity does not guarantee this only more shots.
Your best bet is to buy the truth books on vaccinations and educate yourselves. If you're thinking of having children at some point, they will serve you well.