MEDLINE/PubMed Year-End Processing Activities for 2021 MeSH

The National Library of Medicine (NLM) is currently involved in MEDLINE year-end processing (YEP) activities. These include changing the Medical Subject Headings (MeSH) main headings and subheadings as well as Supplementary Concept Records that standardize names and associated numbers for chemicals, protocols, diseases and organisms that are not main headings. The MeSH edits include maintaining existing MEDLINE citations to conform with the 2021 version of MeSH, and other global changes.

Important Dates

• December 2, 2020: NLM expects to temporarily suspend the addition of fully-indexed MEDLINE citations to PubMed. NLM will continue to add publisher-supplied and in process citations.
• Mid-December 2020: PubMed MEDLINE citations, translation tables, and the MeSH database will have been updated to reflect 2021 MeSH.

For details about the impact on searching from December 2 to mid-December, see: Annual MEDLINE/PubMed Year-End Processing (YEP): Impact on Searching During Fall 2020.

For background information on the general kinds of changes made annually, see: Annual MEDLINE/PubMed Year-End Processing (YEP): Background Information.