Ovid Communications
Database Reloads

Ovid MEDLINE 2021 Reload Update

Dear Ovid MEDLINE Customer:


Further to our message on 4 December 2020, we confirm Ovid MEDLINE is being reloaded to implement 2021 MeSH. We expect the reload to go live on February 22nd, 2021. AutoAlerts will run on Saturday, February 20th, 2021 prior to the reload going live.


You can find more information about the changes to MEDLINE and the 2021 MeSH on this NLM page: https://www.nlm.nih.gov/pubs/techbull/nd20/nd20_medline_data_changes_2021.html


In addition, Ovid will make the following changes to Ovid MEDLINE:


  • Change to the MEDLINE Corrections/Revisions segment (MEDC)
    It has been a longstanding request from our customers to replace corrected records directly in the database, instead of collecting them in a separate database segment (MEDC). With the 2021 reload Ovid will no longer provide a separate monthly updated corrections segment. Corrections provided by the NLM will be placed directly in the corresponding backfiles (MED1 – MED17) covering the years up to and including 2020. Corrections will be processed on a weekly basis (on Wednesdays) for the back files.
    Ovid AutoAlerts will not alert on these backfile segments. Revised records can be identified in the back files by the Revision Date field (RD) and/or the Update Date field(UP). Corrections to 2021 records will be replaced in the current year segment (MEDL) and they will be alerted on.
  • Change to the MEDLINE in-Process and Non-Indexed Citations segment (PREM)
    With the 2021 reload Ovid will move the “Non-Indexed Citations” with Status “PubMed-Not-MEDLINE” out of PREM into their own dedicated segment called PMNM. This change will not affect AutoAlerts. Records with status “In-Process” or “In-Data-Review” will be alerted on in the PREM front segment, while new records with status “PubMed-Not-MEDLINE” will be alerted on in the PMNM front segment.


Your database resources display for Ovid MEDLINE segments may be affected by the changes above. The MEDLINE Corrections segments (MEDC, MEDCM), if you had them listed, will disappear. Databases labelled “Without Revisions” will lose that label, and a new PubMed-Not-MEDLINE segment (PMNMZ) will now be available for display on request.
We would like to remind all customers that database listings on Ovid are fully customizable. There are over 40 combinations of Ovid MEDLINE available for display in the database list. However we strongly recommend to keep things simple for your users, and only show the all-encompassing “Ovid MEDLINE(R) ALL <1946 to Present>” (MEDALL), which is our PubMed equivalent in terms of coverage.
Please note, we will provide all Ovid MEDLINE customers with a complete overview of all available segments in the 2021 reload in a follow-up communication, prior to the reload.


Finally we are pleased to let you know we updated the Special Ovid Filter Limit for Covid-19 in December 2020. We will provide the next update for this filter after the 2021 Ovid MEDLINE reload in February. While updating this filter, we have made sure not to “lose” any records from the previous version of the hedge. As before, the full search syntax and search line comments are documented in the Limits section of the Ovid MEDLINE database guide.


Feel free to contact Customer Support with any questions by sending an email to [email protected].



Wolters Kluwer – Ovid

Tags: MEDLINE,Ovid,