Parents who exercise a vaccine exemption for their children are often ridiculed for putting their own children and others at risk. However, legally and medically, unvaccinated children do not pose a significant health risk to themselves or anyone else. Alternative vaccine views support this assertion, but the reasoning in this article comes straight from mainstream vaccine beliefs, accepted medical practice and current law.
First, from the legal perspective, forty-eight state legislatures, federal agencies (e.g., Department of Defense, U.S. Citizen and Immigration Services), and all U.S. territories offer religious exemptions to immunizations. The state legislatures and federal agencies providing these exemptions are presumed to have considered whether or not the exercise of these exemptions would pose a significant health risk. They would not have enacted these exemption laws if their exercise would pose a significant health risk. Thus, there is a legal presumption that the exercise of a vaccine exemption does not pose a significant risk to anyone.
This legal presumption is not a mere exercise in semantics or logic. It is based on the widely accepted herd immunity theory, which tells us that so long as most of the members of a population are immune, all members of the population are protected. Indeed, current vaccine policy necessarily depends on this theory. The Centers for Disease Control and Prevention (CDC) says: "No vaccine is 100% effective. Most routine childhood vaccines are effective for 85% to 95% of recipients. For reasons related to the individual, some will not develop immunity." (It's curious that they blame the "individual" and not the vaccines. Regardless, the CDC admits that this is why the majority of outbreaks occur in vaccinated children.) In contrast, national exemption rates run about 1% - 2.5% on average. Furthermore, just as vaccinated children are not necessarily immune, exempt children aren't necessarily lacking immunity. Many exempt children develop natural immunity, and according to the CDC, they don't have to get sick for that to happen. The bottom line is, you can't determine the immunity status of any given individual child by the child's vaccination status alone. But with the herd immunity theory, we don't need to; we need only be concerned with a populations' immune status collectively.
Not only do non-immune children (vaccinated or not) not pose a significant health risk now, they pose no potential future risk, as protective laws and procedures have been put into place to account for them. For example, most states require exempt children to stay home from school during a local outbreak, for the duration of the incubation period of the outbreak disease. (Of course, since most non-immune children are vaccinated and they are not required to stay home, this practice discriminates against exempt children, but it is common policy around the U.S.) Most states also have laws that can require emergency vaccines and throw exemptions out the window and/or quarantine of unvaccinated persons in a declared, infectious disease emergency. So, neither exempt children nor their non-immune, vaccinated peers pose a significant health risk—now, or at any time in the future.