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Table of Contents: 2021 NOVEMBER–DECEMBER No. 443

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MEDLINE Data Changes—2022

MEDLINE Data Changes—2022. NLM Tech Bull. 2021 Nov-Dec;(443):e8.

2021 December 16 [posted]

This article collects the notable data changes made to MEDLINE during the National Library of Medicine (NLM) annual maintenance known as Year-End Processing (YEP) for 2022:

MeSH Vocabulary Updated for 2022

The MeSH Browser points to the 2022 MeSH vocabulary with a link to the 2021 MeSH vocabulary. On December 2, the default switched to 2022 and the alternate link has been routed to 2021 MeSH. Searchers should consult the Browser to find MeSH headings of interest and their relationships to other headings. The Browser contains MeSH heading records that may include Scope Notes, Annotations, Entry Terms, History Notes, Allowable Qualifiers (Subheadings), Previous Indexing, and other information. It also includes Subheading records and Supplementary Concept Records (SCRs) for substances, diseases, and organisms that are not MeSH headings.

You can download 2022 MeSH from links on the NLM Data Distribution page for MeSH Data.

The PubMed MeSH database and translation tables will be updated to reflect 2022 MeSH by the middle of December when YEP activities are complete and the newly maintained MEDLINE data are available in PubMed.

Updated MeSH in MEDLINE Citations

MEDLINE citations with updated MeSH are anticipated to be in PubMed by mid-December 2021. See "MeSH Changes and PubMed Searching (2021)" for details on revising My NCBI saved searches.

Changes to MeSH Headings

For 2022, 24 MeSH headings were either changed or deleted and replaced with more up-to-date terminology. During YEP, NLM updates these MeSH headings on MEDLINE citations.

Replaced Term

Replaced-By Term

African Continental Ancestry Group


American Natives

American Indians or Alaska Natives

Anabaena flos-aquae

Dolichospermum flos-aquae

Angiopoietin-like 4 Protein

Angiopoietin-Like Protein 4

Asian Continental Ancestry Group


Casein Kinase Iepsilon

Casein Kinase 1 epsilon



Continental Population Groups

Racial Groups

Dental Models

Models, Dental



Environmental DNA

DNA, Environmental

Ethnic Groups


European Continental Ancestry Group


Fermented Foods and Beverages  

Fermented Foods

Genus Pimenta


Hispanic Americans  

Hispanic or Latino


Household Work


Immunosuppression Therapy





Oceanic Ancestry Group  

Native Hawaiian or Other Pacific Islander

Protein-Serine-Threonine Kinases  

Protein Serine-Threonine Kinases

Purpura, Schoenlein-Henoch

IgA Vasculitis

Translational Medical Research  

Translational Research, Biomedical

New MeSH Headings and Concepts

277 new MeSH descriptors were added to MeSH and 218 new MeSH Supplementary Concept Records were added for 2022.

A complete list of the new 2022 MeSH headings is available in PDF format; see New Headings with Scope Notes, Annotations and Tree Locations.

Typically, NLM does not retroactively re-index MEDLINE citations with new MeSH heading concepts. Therefore, searching PubMed for a new MeSH term tagged with [mh] or [majr] effectively limits retrieval to citations indexed after the term was introduced. PubMed Automatic Term Mapping (ATM) expands an untagged subject search to include both MeSH Terms and All Fields index terms and may retrieve relevant citations indexed before the introduction of a new MeSH term. Searchers may consult the MeSH Browser or the MeSH database to see the previous indexing terms most likely used for a particular concept before the new MeSH heading was introduced.

MeSH Tree Changes

For a list of new MeSH headings by tree hierarchy, see 2022 New MeSH Headings by Subcategory available in PDF format.

COVID-19 Terminology:

Starting in January 2020, new terms related to the 2019 novel coronavirus (SARS-CoV-2) and the resulting disease (COVID-19) were added to the MeSH vocabulary as SCRs.

Additional SARS-CoV-2 SCR terms were added for 2022 MeSH.

Additional SCRs will be created as needed. Please continue to check the MeSH Browser for new SCRs.

Special MeSH Projects

Several special projects resulted in the following new 2022 MeSH headings:

New and Updated Social Determinants of Health Headings:

As a part of ongoing research and study, MeSH added new descriptors and updated concepts as they relate to Social Determinants of Health (SDoH) with help from OBSSR and other NIH ICs.

For example, new Headings:

New Headings related to SARS-CoV-2:

New Infection Headings:

New and Updated Organism Headings:


Other Changes

In addition to changes and deletions of MeSH terms on MEDLINE citations, YEP includes other adjustments to reflect 2022 MeSH vocabulary and enhance search retrieval. These follow-on adjustments are largely meant to add additional MeSH headings or Supplementary Concept Record Names to citations in order to help searchers refine retrieval. In some cases, the changes clarify areas where a single concept existed before but is now represented by two or more specific concepts.

Entry Combination Revisions

This year during YEP, NLM will again retrospectively replace certain MeSH heading/subheading combinations, known as Entry Combinations, with the new pre-coordinated MeSH heading. If you get no retrieval for a MeSH heading/subheading combination, check the heading in the 2022 MeSH Browser to see if the Entry Combination information indicates a different term.

There were four new Entry Combinations for 2022.

Previous MeSH Heading/Subheading
(Entry Combination)

Replaced-by Heading for 2021


Iron Deficiencies

Proprotein Convertase 9/antagonists & inhibitors

PCSK9 Inhibitors

1-Propanol/analogs & derivatives


Shoulder Joint/injuries

Shoulder Injuries

Other News:

Data Distribution Notes

There is no change to the PubMed DTD for 2022. The DTD dated 010119 is still valid.

Because there are no changes to the PubMed DTD, NLM will not create new sample data for 2022.

More information and announcements can be found at Download MEDLINE/PubMed Data.

NCBI Taxonomy Identifiers

Beginning in 2020, NCBI Taxonomy Identifiers (txid) have been added to MeSH records as Registry Numbers (RNs) for SCR-Class 4 Organisms.

At this time, the NCBI Taxonomy Identifiers will not be carried as metadata on MEDLINE citations.

The NCBI Taxonomy Identifiers are available to view in the MeSH Browser where they are displayed in the Registry Number field and denoted by the prefix of txid. NCBI Taxonomy Identifiers are unique numerical identifiers between one and seven digits that are assigned by NCBI to organisms. For example, the NCBI Taxonomy Identifier for SARS-CoV-2 is displayed as Registry Number txid2697049.

For more information on the NCBI Taxonomy Identifiers, see NCBI Taxonomy Identifiers Added to MeSH.

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