FACEBOOK Inc, which has been criticized by lawmakers and researchers for allowing vaccine misinformation to spread on its platforms, said on Monday it has started adding labels to posts that discuss the safety of the shots and will soon label all posts about the vaccines.

The social media company said in a blog post it is also launching a tool in the United States to give people information about where to get COVID-19 vaccines and adding a COVID-19 information area to its photo-sharing site Instagram.

False claims and conspiracies about the coronavirus vaccines have proliferated on social media platforms during the pandemic.

Facebook and Instagram, which recently tightened their policies after long taking a hands-off approach to vaccine misinformation, remain home to large accounts, pages and groups that promote false claims about the shots and can be easily found through keyword searches.

Facebook's Chief Product Officer Chris Cox said in an interview that the company had taken viral false claims "very seriously" but said there was "a huge gray area of people who have concerns...some of which some people would call misinformation and some of which other people would call doubt."

"The best thing to do in that huge gray area is just to show up with authoritative information in a helpful way, be a part of the conversation and do it with health experts," he added.

The company said it was labeling Facebook and Instagram posts that discuss the safety of COVID-19 vaccines with text saying the vaccines go through safety and effectiveness tests before approval.

In the blog post, it also said that since expanding its list of banned false claims about the coronavirus and vaccines in February, it has removed an additional 2 million pieces of content from Facebook and Instagram. Facebook said it had also implemented temporary measures including reducing the reach of content from users who repeatedly share content marked false by fact-checkers.