I have no ide3a, there should be few, as it takes a special kind of intellectual failure to subscribe & promote such packs of falsehoods about both science and history, much based on a fraudulent study that caused the author to be stripped of his degree & Med license. [1][2]
Perhaps more importantly, it needs to be understood that anti-vaxxers are A) freeloading on the herd immunity created and maintained by the smarter people, and B) are directly endangering the set of people who cannot get vaccinated for medical reasons -- they are literally a death threat to many.
Much of this is also people falling for weaponized Russian dezinformatsiya, a very cheap way to both sow discontent, conflict, and illness in their adversaries [3].
You might think, but the Russians have been the world champions of espionage & subterfuge for at least a century. It is an enormous return on investment to deploy a few inexpensive resources and create havoc in your adversaries. Moreover, it is a win-even-if-you-lose situation; you don't need to get everyone to believe your dezinformatsiya (disinformation), you accomplish much even if people simply throw up their hands and say they don't know what to believe. The same with pushing extreme points of view in politics or hoaxes -- it pushes people to disconnect from their society, weakening that society.
https://news.ycombinator.com/item?id=20487229