OK... I am going to say this now before more flawed posts are written. Heavy metals are found in nearly all soils, and forage. A kid will get more heavy metals from a mothers milk the first 6 months then from vaccines it will get its first full year.
Are there "heavy metals" in vaccines? Yes. They are there to server a purpose as with out them as either a stimulant or even as a cleaning agent, a vaccine wouldnt work as well or not at all. So does this mean you shouldnt vaccinate? Its absurd to use this as a reason not to. Loss mineral salt, all stock / dairy ration grains have heavy metals ADDED TO THEM to benefit livestock. Would you refuse to feed them as well? Of course not. All creatures need heavy metals and seeing how we are speaking of such minimal amounts, heavy metals shouldnt even be considered when vaccinating.
The best means to figure if you need to vaccinate is how you manage your animals. How dirty are their conditions. Do they sleep on their own poo? Eat off the ground that is covered in poo? To many animals to closely penned together? A mothers milk is fine if they have the space that is required such as a wild ruminant. But once you start to "feed lot" your animals, vaccines are a must. Think of the difference between say Montana and Cambodia.
This also applies to de worming. The tighter the living conditions, the more you need to adjust your worming habits.
So do you vaccinate? Yes, I believe you do and you do it when and how, with the correct amounts as is widely known and suggested.
Can you get away with not doing it? Sure, a mothers milk is a great immunity builder.
Can either way be dangerous? Of course. But I have never had nor herd of anyone losing hole kid crops because they vaccinated. Yet on the other hand, I have heard the opposite when someone failed to vaccinate. Granted, I deal with large herds, and that is a big factor, as stated above.