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.