The policies cover general statements about vaccines—not only those for Covid-19—and about specific routine immunizations such as those for measles and hepatitis B. YouTube said it has removed more than 130,000 videos for violating its Covid-19 vaccine policies since last year.

“We’ve steadily seen false claims about the coronavirus vaccines spill over into misinformation about vaccines in general,” YouTube said. “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.”

YouTube has permanently cut off several channels tied to what it regards as well-known spreaders of vaccine misinformation, a spokeswoman said. They include those belonging to Joseph Mercola and an account affiliated with

Robert F. Kennedy Jr.

, she said.

“Free speech is the essential core value of liberal democracy. All other rights and ideals rest upon it. There is no instance in history when censorship and secrecy have advanced either democracy or public health,” Mr. Kennedy said in a statement through a representative.

In response to the termination, Dr. Mercola said in a post on Twitter that “anyone who asks questions or challenges the hard sell is immediately censored on social media.”

YouTube said it would continue to allow videos on vaccine policies, new vaccine trials and historical vaccine successes or failures, as well as personal testimonials related to the vaccines. That policy reflects what the company sees as the importance of public discussion and debate, it said.

Also this week, YouTube said it suspended the posting privileges of RT DE, the German-language service of Russian state-owned media company RT, over Covid-19 misinformation. YouTube said it subsequently suspended another channel the broadcaster used to circumvent the suspension.

Russia’s foreign ministry said on Twitter that the action represented “flagrant censorship and suppression of freedom of expression” and that Russia was looking at retaliatory measures.

Other social-media platforms also have policies to suppress Covid-19 falsehoods.

Twitter Inc.

earlier this year said it began applying labels to tweets pertaining to vaccines that include conspiracy theories and rhetoric that isn’t based in research or credible reporting.

Facebook Inc.

has also aimed to use its resources to promote Covid-19 vaccines. But its researchers warned that comments on vaccine-related posts—often factual posts of the sort Facebook sought to promote—were filled with antivaccine rhetoric aimed at undermining their message, internal documents reviewed by The Wall Street Journal show. A company spokesman said that for people in the U.S. on Facebook, vaccine hesitancy has declined by about 50% since January.

Write to Dave Sebastian at dave.sebastian@wsj.com