We have four unvaxed children and they have inherited my hypothyroid and consequent adrenal issues. I am treating them for this presently and they are healing well. I don't know if these will be life-long issues or not. They grew in my hormonally-deficient body and may have underdeveloped glands as a result of that.
I have documented vax damage, and I am certain that given our boys' consequent glandular deficiencies, they would have too, if we had subjected them to vaccines.
We also don't give them any pharmaceuticals and treat all health issues from the perspective of equipping the body to heal itself.
Our whole lifestyle would tend toward having healthy children, which they are in general, and especially now having relief with nourishing their bodies for glandular healing.
I wanted to add that not having immune system responses to illnesses such as not vomiting or coughing up phlegm isn't necessarily a sign of a healthy immune system. It can be a symptom of an inadequate immune system that cannot use these functions to get rid of illness. This was me for many years.
In the past month, I have coughed for the first time in three years and even vomited from a flu. This is an enormous improvement for me, and a wonderful indication that my immune system is now functioning! Previously, I would catch a cold and my lungs would just fill part-way with phlegm that I wouldn't cough up at all. I'd feel like I was breathing under water and be laboured in breathing for months before it would subside only to return with the next virus. I was always tired, carrying around viruses that my body couldn't respond to.
I only share this because the indications of health are rarely how little our bodies respond to the environment, but
how they respond. For instance, our ds2 has a fabulous immune system. We know this because when he contracts a virus, he has roaring fevers that peek within a few minutes and stay high for a while, then continue to peek in intervals that are short at first and then slow down as his body kills off the virus. He has rarely had a virus that has lasted more than overnight (mumps was 3 days and very mild once the fever did its work), and he goes through the whole thing and all of its symptoms super fast- he doesn't skip any of the responses, such as some think indicates health.
I have a friend who thinks her children are very healthy, but they have colds that come back after they seem to be going away and this can go on for months at a time. Then, they don't vomit with a flu, but just end up lethargic for days and feverish, but with mild temps. They are obviously overgrown with yeast, and this is affecting their immune responses, but she thinks their lack of response is an indication that they are dealing with the illnesses well. It simply isn't the case.
Non-vaxed children aren't as a group healthier than unvaxed children, imo. They are individually as healthy as they can be in their situation, and vaxed children just have a specific imposed obstacle to their health potential that unvaxed children do not. Many unvaxed children eat very poorly and many vaxed children eat well.
It's not possible to answer this question in general since the 'control group' isn't in a lab where every variable can be accounted for. I personally take the perspective that my children will develop into their potential as we/they meet their individual needs. I wouldn't add anything to them that might hinder them (knowingly), and so many things that others consider normal are not part of our life, and that includes vaccines. I don't withhold vaccines from them because I think they'll be healthier; I allow/participate with them to develop to their health potential according to their constitutions and needs, incorporating every variable as I/we become aware.
Vaccines are so far from my perspective on what defines health as to not even be considered, except that this thread showed up on the front page, so I joined in.

I believe that my particular children are healthier than they would be if I injected them with pathogens and toxins. I think that is true for everyone. But I don't know if my children are healthier than yours or anyone else's.