Expressions of concern are “used to raise awareness to a possible problem in an article” (Council of Science Editors, 2012). They are a relatively new, rare, and non-standardized type of editorial notice compared to corrections or retractions and “considerable differences in policy and practice remain between journals” (Vaught et al., 2017). The COPE Retraction Guidelines describe when journals could use expressions of concern. For example, editors should consider an expression of concern if:

• they receive inconclusive evidence of research or publication misconduct by the authors
• there is evidence that the findings are unreliable but the authors’ institution will not investigate the case
• they believe that an investigation into alleged misconduct related to the publication either has not been, or would not be, fair and impartial or conclusive an investigation is underway but a judgment will not be available for a considerable time COPE advises that expressions of concern should be linked to the article and state the reasons for the concern.

If more evidence becomes available the expression of concern could be replaced by a retraction notice or an exonerating statement, depending on the outcome.