There are people out there who think that vaccines are linked to autism. They are wrong. There is no evidence to support their belief, and tons of evidence against it. However, because they have celebrity spokespeople who are loud but appealing, and because their targets are worried parents, they have made seriously headway in society. For that reason, I consider antivaxxers to be one of if not the largest health threat in the US. We have already seen a drop in vaccinations in the US and UK and an increase in measles outbreaks due to their efforts (pertussis is on the rise, too, though the cause is as yet unclear), and while there have been few deaths from their antiscientific crusade so far -- and even one is too many -- you can bet there will be more. Many more. And now there may be a further impact. It appears some insurance companies are refusing to pay for some vaccinations. It's not clear if this is due to the drop in requested vaccinations because of antivax efforts, or if rising costs and the usual insurance company reluctance to provide actual coverage is to blame. The survey on which this article is based doesn't say, but it would be an excellent idea to find out why this is happening. If we start to see an even higher increase in childhood diseases -- and fatalities -- that can be traced to the exhortations of Jenny McCarthy and Andrew Wakefield, then it is critically important that parents of young children know exactly what and who is behind the problem.