YouTube will block all anti-vaccine content, the video-sharing platform said in a blog post on Wednesday.

The Google-owned site will block content that alleges vaccines cause chronic health effects or contains misinformation on the substances in vaccines.

The company previously blocked videos that made those claims about coronavirus vaccines, but not ones for other vaccines such as those for measles or chickenpox.

YouTube is also banning prominent anti-vaccine activists — including Robert F. Kennedy Jr. and Joseph Mercola — taking down several channels, the Washington Post reported on Wednesday, citing YouTube's Vice President Of Global Trust and Safety, Matt Halprin.

Slowing vaccination rates prompts concerns 

The move follows concerns over the role anti-vaccine activists have played in slowing vaccination rates across the US by fueling skepticism. The popular social media platform streams more than a billion hours' worth of content every day.

Public health officials have struggled to counter the current of online misinformation about the COVID-19 vaccine.

YouTube didn’t expand the ban sooner because it was focusing on misinformation specifically about coronavirus vaccines, Halprin said.

When the company noticed that incorrect claims about other vaccines were contributing to fears about the COVID-19 vaccines, it expanded the ban.

"Developing robust policies takes time," Halprin said. "We wanted to launch a policy that is comprehensive, enforceable with consistency and adequately addresses the challenge."

Vaccination rates have slowed ꟷ about 56% of the US population have had two shots, compared with 71% in Canada and 67% in the UK, the Washington Post reported.

Tech giants such as Facebook, Twitter and YouTube have previously come under fire for taking insufficient steps to prevent the spread of false health information on their platforms. They have long argued that maintaining an open platform is essential to free speech. 

mvb/aw (Reuters, AP)