John Oliver summed up the problem with the anti-vaccine movement on "Last Week Tonight" in one line:

"Opportunistic quacks writing books that fan the flames of people's unfounded fears don't cause a legit public health hazard, except when they do."

Oliver was talking about Robert Sears, a paediatrician who promotes the idea that vaccines could be safely administered to children over a longer period of time, rather than all at once as is traditionally done.

Sears' approach has been portrayed as a sort of middle ground between anti-vaccination naysayers, who wrongly claim that vaccines are dangerous, and the medical community's consensus that vaccines are safe and necessary.

The problem is that Sears' method doesn't work. No scientific studies suggest there's a benefit to his technique, and a mountain of evidence supports the fact that vaccines are important and effective. 

There is no safe alternative to vaccination, and research has shown that spacing out vaccines can have harmful results.

"Infants and young children who follow immunisation schedules that spread out shots … are at risk of developing diseases during the time that shots are delayed," the Centres for Disease Control and Prevention wrote in its vaccination guidelines.

The frightening consequences of spreading out, delaying, or avoiding vaccinations has already been seen in the recent measles outbreaks in the US.

Nevertheless, a growing number of parents have expressed worries about vaccines.

That controversy, Oliver says, can likely be traced back to a 1998 press conference called by London's Royal Free Hospital, which publicised a research paper published in the medical journal The Lancet. That paper has since been withdrawn from the journal. 

The paper's author, Andrew Wakefield, said during the conference that his research suggested a link between the measles-mumps-rubella (MMR) vaccine and the onset of autism, a neurodevelopmental disorder characterised by impaired social interaction.

Wakefield's results - which actually came from a small and poorly done study - were wrong.

Dozens of large-scale studies done since then, including a Danish study of close to half a million children, have sought to redo Wakefield's work in an attempt to replicate and essentially prove his results.

So far, none have found an association of any kind between autism and the MMR vaccine.

The Lancet retracted Wakefield's paper in 2010, after an investigation revealed not only poor science but also financial conflicts of interest. Wakefield was stripped of his medical licence a year later.

Nevertheless, what John Oliver calls "scary vaccines stories" continue to circulate. And this can translate into real challenges. There are now 11 states where the number of unvaccinated kids is on the rise, according to STAT News.

Oliver is determined to follow the science, however. At the end of the episode, he announces that he plans to vaccinate his 19-month old son "fully and on schedule."

Watch the full "Last Week Tonight" episode below (or if you're outside the United States, view the video here.)

This article was originally published by Business Insider.