YouTube has said it will remove videos that falsely claim approved vaccines are dangerous, as social networks seek to crack down on health misinformation around Covid-19 and other diseases.
The video-sharing platform has already banned posts that spread false myths around coronavirus treatments, including ones that share inaccurate claims about Covid-19 vaccines shown to be safe.
But the Google-owned site said its concerns about the spread of medical conspiracy theories go beyond the pandemic.
"We've steadily seen false claims about the coronavirus vaccines spill over into misinformation about vaccines in general," YouTube said in a statement.
"We're now at a point where it's more important than ever to expand the work we started with Covid-19 to other vaccines."
The expanded policy will apply to "currently administered vaccines that are approved and confirmed to be safe and effective by local health authorities and the WHO (World Health Organization)."
It will see false claims about routine immunisations for diseases such as measles and Hepatitis B removed from YouTube.
These would include cases where vloggers have claimed that approved vaccines do not work, or wrongly linked them to chronic health effects.
Content that "falsely says that approved vaccines cause autism, cancer or infertility, or that substances in vaccines can track those who receive them" will also be taken down.
"As with any significant update, it will take time for our systems to fully ramp up enforcement," YouTube added.
It stressed there would be exceptions to the new guidelines, with personal testimonials of negative experiences with vaccines still allowed, so long as "the channel doesn't show a pattern of promoting vaccine hesitancy."
YouTube said it had removed more than 130,000 videos since last year for violating its Covid-19 vaccine policies.
It is not the only social media giant grappling with how to deal with the spread of Covid-19 conspiracy theories and medical misinformation in general.
Facebook this month launched a renewed effort to tackle extremist and conspiracy groups, beginning by taking down a German network spreading Covid misinformation.
Russia threatens to ban YouTube
Meanwhile, Russia has threatened to block YouTube and the Kremlin called for "zero tolerance" towards the video hosting giant after it removed Russian state-backed broadcaster RT's German-language channels from its site.
The online video company owned by Alphabet Inc deleted Russian state-backed broadcaster RT's German-language channels on Tuesday, saying they had breached its Covid-19 misinformation policy.
Russia said it was considering retaliating against German media and also accused YouTube of "unprecedented information aggression" after the company's move against the RT channels.
The row creates a new line of tension in Russia's standoff with foreign tech giants and its long-running push to assert greater sovereignty over its segment of the internet.
Russian state communications regulator Roskomnadzor said it had written to Google and demanded that the YouTube restrictions on the RT channels be lifted. Russia could partially or fully restrict access to YouTube if it failed to comply, it added.
Google declined to comment on the matter.
Russia could impose measures to force YouTube to comply with its laws, Kremlin spokesman Dmitry Peskov told reporters, adding that the law appeared to have been broken in this case.
"There should certainly be zero tolerance for this kind of breaking of the law," he said.
Russia's foreign ministry said it would draw up "a proposal to develop and take retaliatory measures against the YouTube hosting service and the German media".
Vasily Piskarev, a lawmaker who heads a parliamentary commission to investigate foreign meddling, said Russia had grounds to take measures against Deutsche Welle, the TASS news agency reported.
Christian Mihr, executive director at Reporters Without Borders (RSF) Germany, said the threat of action against German journalists was "completely inappropriate".
Berlin denied an allegation by the Russian foreign ministry that YouTube's decision had been made with clear and tacit support from the German authorities and local media.
"It is a decision by YouTube, based on rules created by YouTube. It is not a measure (taken by) the German government or other official organisations," German government spokesperson Steffen Seibert told reporters.
Moscow has increased pressure on foreign tech firms in the past year, fining social media companies for failing to delete content Russia deems illegal and punitively slowing down the speed of Twitter.
Separately today, Russia fined Google 6.5 million roubles ($89,534), the latest in a series of small penalties for failing to delete content that Moscow deems illegal.
The Kremlin's critics say that mounting pressure on Google and Apple had pushed the media giants to remove an anti-government tactical voting app from their stores on the first day of a parliamentary election this month.