A new version of PubMed has been in the works for some time now, and as of May 18, 2020, this new database will be the default. Users will still be able to access what is now being referred to as the “legacy” version of PubMed, however this will be retired altogether “a short period of time” afterwards.
There have been some concerns regarding the potential lack of reproducibility in the new PubMed, since this database utilizes artificial intelligence (AI) when calculating search results. In other words, popular searches that take place on a particular day may influence the results that are yielded from a search. Those interested in conducting systematic reviews in the future may want to consider utilizing MEDLINE which is currently available through the University Libraries via both the EBSCO and Ovid platforms, as these databases do not currently utilize AI.
For additional information on the transition, please consult the New PubMed FAQs: https://support.nlm.nih.gov/knowledgebase/article/KA-05275/en-us