Just a thought... if your kid is immunized and mine isn't, what's it to you?
I think what underlies his question is an assumption that getting immunized prevents the disease 100% of the time. The problem is that it doesn't- that's why it takes boosters and repeating the shots several times during childhood. The complete series for childhood takes several years to complete. Immunizations work on the concept of "herd immunity"- the fewer cases of disease in a group of people also lowers the chance of illness for the rest of the group. As long as there is one unimmunized child in the group, it increases the risk for the rest of the group, even those who have been immunized.
Actually I thought more of the scope of the affect of vaccination (but I'm not sure enough to actually give an appropriate answer), but yeah the answer to that also concerns the concept of herd immunity, something a lot of people don't know nor think of.
Here explaining it even further for Mike, plus some extra point.
A lot of people think that vaccination affects only the ones being vaccinated, and thus is more of an issue of autonomy. It's not. With vaccination, we're concerning and dealing with infectious diseases, diseases that can be spread amongst people, from person to person, with an eventual impact to the community. Like measles or the now gladly extinct smallpox, the infectious rate of these infectious diseases are alarming, and this is where vaccines also exert its effect via herd immunity - or simply put, how vaccinated people protect the people in their immediate community from contracting an infectious disease.
Suppose in a 100-people community, only 5 people are non-vaccinated for any reason, and 1 person got measles. Like Kara mentioned, despite not being a cure-all, the vaccine prevents to a great measure infection and spreading in those already vaccinated. So in this case, the remaining 95 vaccinated people has minimal risk of being infected - and limiting the spread of the disease. And unless the remaining 4 non-sick non-vaccinated people regularly comes to close contact to the sick person, the spread of measles to these 4 people are limited because (almost) everyone around them don't have measles and therefore cannot infect them with measles. In other words, these non-vaccinated individual receive indirect protection against the disease from vaccinated people.
A lot of people against vaccination tend to take this for granted, because they think that this herd immunity will protect every non-vaccinated people all the time, so they don't have to participate in the program. That is however a mistake and a weak link in herd immunity.
Let's say in the future a lot of people in the said community decide not to vaccine their children, so that now 60 in the 100 people community are not vaccinated. Again comes measles to one person. This time, there's only 40 people protected in the society, and measles can easily spread between the rest of 59 people; the protection is outnumbered here. Thus the communal protection doesn't work best here since it cannot guard all the possible way/route of communal infection here.
Simply put, the herd immunity of vaccination works better in protecting the community the more people get vaccinated. On the contrary, the more amount of people unvaccinated, the higher the risk of infection is amongst people, and people who are not vaccinated do not only endanger themselves, but also another people who are not vaccinated for any reason - which is the next point people need to know.
In the first year or so of an infants' life, they have a limited amount of immunity that is passed on from their mother. Because an infant's immune system is still developing, it's a time when they are the most vulnerable to diseases like pertussis, measles and influenza- diseases that an adult or an immunized older child would survive, but could be lethal for an infant.
Unimmunized children aren't as much a risk to immunized children as they are to older adults. A child with influenza passing along the flu to an elderly person is also a problem.
This is a good point Kara brought up, but there are other instances when protection from vaccines extends even further.
Not getting vaccinated because one refuses to is a matter of autonomy, but there are plenty of people who cannot be vaccinated for many reasons. For example, people with inborn/acquired immune deficiency (like HIV/AIDS), people with some types of autoimmune diseases, or people with leukaemia, in which vaccines, particularly the live types, may possess some health hazards. These people might have gotten vaccination before they had their diseases but cannot receive boosters for the same reasons.
These people are not only extremely vulnerable to the infectious diseases, but the said diseases are often more severe and deadly because they have weaker immunity systems, which puts them in place like newborn infants. Another subset of population sensitive to these infection would also cover people under immunosuppresive therapies (ex. transplant patients, autoimmune under therapy); old people (with weakened/blunted immune responses); and people with underlying conditions in which vulnerability to infection is increased some infectious conditions may be dangerous for them (like diabetes, chronic kidney disease particularly undergoing dialysis, cystic fibrosis).
These people are largely dependent on, or can only be protected from certain infections via, the herd immunity, and therefore are very sensitive to changes in the community. The more people are not vaccinated, the higher risk there is for these vulnerable people to get infected. It's not fair to expose these disadvantaged portion of the population to diseases when the weakened immunity/not being vaccinated is not their own decision to make.
In short: vaccination has wider scope and issue than simply a matter of autonomy (me vs them), but it's a community health matter. If you're vaccinating your child/taking a vaccination, you're not only contributing to your own health and disease prevention, but also the community's via participation in herd immunity.
