Instagram has removed the account of Robert F Kennedy Jr for making false claims about coronavirus and vaccines.
The nephew of late President John F Kennedy had his account permanently taken down "for repeatedly sharing debunked claims", Facebook, which owns Instagram, said in a statement.
His Facebook account remains active despite similar claims posted there.
These have included linking the death of legendary baseball player Hank Aaron to the Covid-19 vaccine.
Facebook has vowed to remove false claims about Covid-19 vaccines to prevent "imminent physical harm".
Mr Kennedy, a lawyer and environmentalist, is the son of late former US attorney general, senator and presidential candidate Robert F Kennedy.
He chairs Children's Health Defense, a group that expresses scepticism about the health benefits of vaccines. He also campaigned against the immunisation of measles during a resurgence of the infection.
Speaking last year at a conference for the National Vaccine Information Centre, a controversial group accused of spreading misinformation on vaccines, Mr Kennedy said people were hearing his message and "those seeds are landing on very fertile ground".
He has addressed anti-lockdown protests and his videos are regularly translated by activists based in other countries.
In December, his niece, Kerry Kennedy Meltzer, a physician, wrote a piece in the New York Times entitled: Vaccines Are Safe, No Matter What Robert Kennedy Jr Says.
Too little, too late?
By Olga Robinson, BBC Monitoring
Mr Kennedy's Instagram account had been a key source of bad information about Covid-19 and vaccines.
But his personal account on Facebook - with over 300,000 followers - is still active on the platform.
The accounts of Children's Health Defense are also still up on both Instagram and Facebook. Combined they have well over 300,000 followers in total. And although Instagram has started to take action against other accounts spreading misleading health information, many still remain.
For critics of the social media companies, it will be further evidence that the tech giants are too slow to combat misinformation.
Mr Kennedy, like many other influential figures in the anti-vaccination community, promoted bad science about the coronavirus and vaccines to hundreds of thousands of social media users throughout the pandemic.
Claims echoing his and others' anti-vaccine narratives now routinely appear in private Facebook groups discussing Covid-19 vaccines - and they spill over into other forums - everything from Twitter to family chats on WhatsApp.