Your feature on sharing laboratory materials (Nature 625, 841–843; 2024) cites evidence for an open-access citation advantage dating back to 2006 (G. Eysenbach PLoS Biol. 4, e157; 2006). There might be many compelling arguments for open-access publishing for the benefit of science and scholarship, but there is currently little firm evidence that a citation advantage is one of them.

The hypothesis that articles with an open-access status are more highly cited than those without has been a matter of active research for decades. The 2006 publication quoted in the article was one of 134 included in a 2021 systematic review of studies of citation rates of open-access and non-open-access articles (A. Langham-Putrow et al. PLoS ONE 16, e0253129; 2021). Although almost half of these confirmed the existence of an advantage, around one-quarter did not and the remaining one-quarter found one only in subsets of their study sample.

However, only 3 of the 134 studies were found to have a low risk of bias: one supported the existence of the open-access advantage, one did not and the other found one only in subsets. The study quoted was not among these three studies, calling into question the veracity of the trend you highlighted.