BreachScout BreachScout Breach Records

Regulator-posted notice

Breach notice filed by Health Plan of San Mateo (March 2023)

Organization named: Health Plan of San Mateo Provisional: identity as filed, not yet matched to the directory
Type as the source lists it: Hacking/IT Incident

What the sources say

HHS OCR breach portal (HIPAA breaches affecting 500 or more individuals) Primary notice

Posted on the HHS Office for Civil Rights breach portal with a submission date of March 17, 2023.

Organization as reported
Health Plan of San Mateo, CA
Entity type as reported
Health Plan
Category as reported
Hacking/IT Incident
Location of information as reported
Email
Submission date
March 17, 2023
Observed by BreachRecords
2026-10-18 16:15 UTC (revision 10854, row:1993)
Archived copy
Held in the private archive (provenance)

The covered entity (CE), Health Plan of San Mateo, reported that an employee was the subject of an email phishing scheme that affected the protected health information (PHI) of 11,894 individuals. The PHI involved included names, dates of birth, diagnoses/conditions, medications, and other treatment information. The CE notified HHS, affected individuals, the media, and posted substitute notice on its website. In response to the breach, the CE implemented additional administrative, technical, and security safeguards.

The source's own words, from the revision above.

Figures, per source

  • 11,894 individuals affected (total reported), according to the HHS Office for Civil Rights breach portal, source date March 17, 2023, revision observed 2026-10-18.

Each figure is one source's figure with the basis that source gave. Figures from different sources are shown side by side and are not added, averaged or chosen between.

Timeline

Source dates are the dates the sources give. Observation dates are when BreachRecords recorded each revision.

  • Submission date (HHS Office for Civil Rights breach portal)
  • Observed by BreachRecords (revision 10854)
  • Approved by a reviewer

Organizations linked by a reviewer

  • Health Plan of San Mateo Named as the covered entity Provisional: identity as filed, not yet matched to the directory Linked 2026-10-19, method provisional.

Archived evidence

  • 3dbc27dd5742e041cc1e7fe18cc669e2901fbd3b86b7007ed27948ff4d406e1f
    text/csv, 5,530,996 bytes, retrieved from HHS Office for Civil Rights breach portal, 2026-10-18 16:15 UTC. Archived privately · Provenance · Source page

Records reflect source filings as of the dates shown. BreachRecords is not a regulator.

Request a correction

A record that disagrees with its source, names the wrong organization or duplicates another is corrected after review. This form is about Breach notice filed by Health Plan of San Mateo (March 2023). We acknowledge every request within two business days. We reply by email.

The form is being set up. Check back soon.