London, UK - When it comes to Covid-19 vaccine misinformation, the voices of few reach many, according to a new study.

Approximately 65% of misinformation about the vaccine that’s spread on social media can be traced back to 12 people, says the Center for Countering Digital Hate in a recent report.

The nonprofit organization refers to those 12 people as the "disinformation dozen."

"Our sample of anti-vaccine content was shared or posted on Facebook or Twitter a total of 812,000 times between February 1 and March 16 2021, with 65 percent of that sample attributable to the Disinformation Dozen," the center’s report reads.

Included in that "disinformation dozen" is Robert F Kennedy Jr., as are the husband-and-wife duo Ty and Charlene Bollinger, the Center for Countering Digital Hate (CCDH) says.

"While some anti-vaxxers identified by CCDH have been removed from a single platform, comprehensive action has yet to be taken, and most remain active on Facebook, Instagram and Twitter," the organization says.

The center says "deplatforming repeat offenders" is the best way to stop the misinformation from spreading.

Last week, President Joe Biden criticized the spread of misinformation on social media platforms such as Facebook.

"They're killing people," Biden said.

A day later, Facebook shared a blog post contending that it takes action against misinformation, saying it has removed 18 million such instances since the pandemic started.

"The data shows that 85 [per cent] of Facebook users in the US have been or want to be vaccinated against COVID-19," reads Saturday’s blog post. "President Biden’s goal was for 70% of Americans to be vaccinated by July 4. Facebook is not the reason this goal was missed."

US Surgeon General Vivek Murthy, meanwhile, spoke out against the spread of false information Sunday during an interview on CNN’s State of the Union.

"All of us – including the media, including individuals, health professionals – have a responsibility to share the truth about health, as science dictates," he said.