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
• Updated MeSH in MEDLINE Citations
• Changes to MeSH Headings
• New MeSH Headings and Concepts
• MeSH Tree Changes
• COVID-19 Terminology
• Special MeSH Projects
• Entry Combination Revisions
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• Data Distribution Notes
• NCBI Taxonomy Identifiers

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	Blacks
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	Asians
Casein Kinase Iepsilon	Casein Kinase 1 epsilon
Cingulata	Xenarthra
Continental Population Groups	Racial Groups
Dental Models	Models, Dental
Echidna	Tachyglossidae
Environmental DNA	DNA, Environmental
Ethnic Groups	Ethnicity
European Continental Ancestry Group	Whites
Fermented Foods and Beverages	Fermented Foods
Genus Pimenta	Pimenta
Hispanic Americans	Hispanic or Latino
Housekeeping	Household Work
Immunosuppression	Immunosuppression Therapy
Insectivora	Eulipotyphla
Kinesin	Kinesins
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:

• Economic Stability
• Housing Instability
• Environmental Justice
• Community Support
• Social Vulnerability
• Access to Healthy Foods
• Social Structure
• Child Poverty
• Social Deprivation
• Home Environment
• Neighborhood Characteristics
• Perceived Discrimination
• Sociodemographic Factors
• Census Tract
• Health Inequities
• Intersectional Framework
• Ostracism
• Systemic Racism
• Social Status
• Ethnic and Racial Minorities
• Social Cohesion
• Social Integration

New Headings related to SARS-CoV-2:

• 2019-nCoV Vaccine mRNA-1273
• BNT162 Vaccine
• Ad26COVS1
• ChAdOx1 nCoV-19

New Infection Headings:

• Persistent Infection

New and Updated Organism Headings:

Viruses:

• Defective Interfering Viruses

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/deficiency	Iron Deficiencies
Proprotein Convertase 9/antagonists & inhibitors	PCSK9 Inhibitors
1-Propanol/analogs & derivatives	Propanols
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.