From the NCBI Insights Blog:
PubMed Commons has been a valuable experiment in supporting discussion of published scientific literature. The service was first introduced as a pilot project in the fall of 2013 and was reviewed in 2015. Despite low levels of use at that time, NIH decided to extend the effort for another year or two in hopes that participation would increase. Unfortunately, usage has remained minimal, with comments submitted on only 6,000 of the 28 million articles indexed in PubMed.
While many worthwhile comments were made through the service during its 4 years of operation, NIH has decided that the low level of participation does not warrant continued investment in the project, particularly given the availability of other commenting venues.
The discontinuation plan is as follows:
New comments will be accepted through February 15, 2018.
Comments will continue to be visible on the PubMed and PubMed Commons websites through March 2, 2018.
Users wishing to access the comments after March 2, 2018, will be able to download them from NCBI’s website.
Many thanks to all of you who participated in this experimental effort to enhance the opportunities for interaction about published biomedical literature.