Host John Oliver has taken on the anti-vaxxers in a powerful monologue.

Last Week Tonight host John Oliver has addressed the growing anti-vaccination movement, calling vaccinations “one of humanity’s most incredible accomplishments” for saving “millions of lives”.

In his opening monologue, Oliver focused on the rise in anti-vaxxers, which he says has been amplified by the “human megaphone” that is Donald Trump.

Oliver explained at one stage people lined up for the polio shot “like it was an iPhone”, but now there is growing unwarranted skepticism around vaccinations.

“Despite their success, small groups are both skeptical and vocal about vaccines, which is nothing new,” he said.

“But these days their voice has been amplified by the human megaphone that is the president of the United States.”

Oliver said that during his campaign Trump advocated for "smaller doses" of vaccines because "tiny children are not horses".

Oliver went to explain that although the myths around vaccination have already been debunked, there's still a lot of misinformation in the anti-vax community and that's leading an alarming number of people to not vaccinate their kids.

“Parents get so much information, it is hard to know what to do,” he said. “Did you vaccinate? Did you eat the placenta? Did you let kids cry? And the answer to those, by the way, are yes, no and absolutely, because the more they cry now the more they’ll be prepare to watch This Is Us when they get older."

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Oliver finished off his monologue on a personal note: “Parenthood in general is f**king terrifying. And I am someone who is scared of literally everything."

"For what it’s worth, I have a son. He is 19 months old. He was born prematurely following a very difficult pregnancy. And I was worried about his health and I still worry about his health a lot. But we are vaccinating him fully on schedule. And if I can overcome the temptation to listen to the irrational shouting of my terrified lizard brain, then I believe that everyone can.”