A news article about a doctor who died after receiving a Covid-19 vaccination was Facebook's most viewed link in the US in the first quarter of 2021, a previously shelved report shows.
The piece - updated after a report said there was no proven link to the vaccine - was popular with vaccine sceptics.
The New York Times claimed that Facebook initially held back its report because it would "look bad".
Facebook said the delay was in order to make "key fixes".
The company had already published its "Widely Viewed Content" report for the second quarter of 2021, in which it found a word search promising to reveal "your reality" was the most popular post.
Similarly frivolous "question posts" formed most of the top 20.
But the New York Times revealed on Friday that the company had held back the earlier report covering January to March 2021.
The paper alleged the report had not been shared because of fears that it would "look bad for the company".
The most-viewed link was an article published by a mainstream US newspaper reporting that a doctor had died two weeks after getting a Covid-19 vaccine. The link attracted nearly 54 million views.
The article was subsequently updated to reflect the findings of the Medical Examiner that there was insufficient evidence to conclude whether the vaccine was responsible for the death.
Health bodies around the world have deemed the vaccine to be both safe and highly effective.
The first quarter report also revealed that the 19th most popular page on the platform belonged to the Epoch Times, which has been accused of spreading right-wing conspiracy theories.