Twitter places an unsafe link warning on an American Heart Association journal abstract: Links to the abstract section of an American Heart Association study have received an "unsafe link warning" that users must click through to view the content. The study observed an increased risk of Acute Coronary Syndrome after receiving the Pfizer or Moderna mRNA vaccines. Users who clicked on the link to the abstract of the study were met with a warning that read, "The link you are trying to access has been identified by Twitter or our partners as being potentially spammy or unsafe, in accordance with Twitter's URL policy." Twitter added several potential reasons why the link might be unsafe, including a suggestion that the link may point the user to "violent or misleading content that could lead to real-world harm."