The antivaccine movement is deeply immoral.
I'm told that mathematicians and physicists get a lot of mail from folks with "big discoveries". These discoveries are often of the "Einstein was wrong and I figured out the Theory of Everything" variety. Many of us refer to these folks as "cranks", a catch-all, derogatory term for people who, through their own arrogance and ignorance, think they have, despite little education or work, disproved ideas that have taken lifetimes to assemble.
Enter the anti-vaccination cranks. Immunoprophylaxis---the manipulation of the immune system to prevent disease---is centuries old, and over those centuries has become more refined and sophisticated. We have moved from inoculating people with smallpox pus to using recombinant DNA to create safer vaccines. We have moved from the Royal Experiment, in which a few prisoners were inoculated and counted, to sophisticated epidemiologic methods of evaluating the burden of disease and the efficacy of vaccination. We have eradicated some diseases, and could, with adequate commitment, eliminate more though mass vaccination programs. In the two centuries since smallpox vaccination became an accepted technique, biology, medicine, and epidemiology have become modern, science-based fields that allow for creation of methods and materials to prevent disease, and the means to evaluate their efficacy.
But human beings are superstitious animals. Like the ancients, we use our personal experiences to create generalizations about how the world works, generalizations that often fail when examined in a more rigorous manner. If we get a flu shot, and then get sick, we blame the flu shot, despite the flu shot's inability to cause a rhinovirus infection.
Individuals can hardly be blamed for making intelligent guesses about their environment. But in order to have a functioning, modern society, we need experts. I can't design and build a bridge, so I rely on engineers to do it. To let "just some guy" do it would be foolish. If someone says that they have a "big discovery" about bridges, most of us would laugh it off. But what if they managed to convince lots of others that modern bridges designed by fancy engineers with fancy degrees were unsafe, that "just some guy" had found a new way to build safer, better bridges, bridge free from the nefarious influences of no-bid contracts and government corruption. He enlists famous people to help sell his idea, to convince people to avoid "dangerous modern bridges" and to use "safer bridges, bridges that take into account individual differences, bridges that you, as a parent, can feel good about." If he convinces one or two people to do this, we write them off as fools. If he convinces hundreds or thousands, we call it a cult and get worried. If he convinces politicians and other people with influence to support his idea, we call it a public health menace.
There is no difference between alternative bridge builders and anti-vaccination activists. They are a cult driven by delusional ideology. When the bulk of the evidence fails them, they claim that "the fix is in", that a conspiracy has created the data with which they disagree. But science is more brutal than they realize. Science has only a fleeting tolerance for fads and for corruption. Scientists as human beings are corruptible. The methods they practice are as well, but for long. This is because science is not a set of beliefs about reality as much as it is a set of methods for discovering reality. We can corrupt the answers some of the time, but not all of the time. No conspiracy is vast enough to create widespread and enduring scientific lies because somewhere, competing scientists want to show everyone how wrong you are.
Anti-vaccinationists are nihilists with little understanding of science or scientists. What they do understand, and practice exquisitely well, is how to manipulate fear and ignorance in the furtherance of their belief system. This makes them not only ignorant but immoral.