California COVID-19 Probable Cases from Antigen Testing

California's Department of Public Health tracked probable COVID-19 cases, defined by positive antigen test results, to monitor community impact. This dataset is archived and no longer updated following the end of the COVID-19 Public Health Emergency. It excludes 17,467 cases from at-home tests reclassified as 'suspect' and lacks data from San Diego County.

Use Cases

• Analyze trends in probable case volume over time to understand the impact of expanded antigen testing.
• Compare the proportion of probable cases to total cases to assess shifts in testing methodologies and surveillance importance.
• Examine the temporal distribution of cases, such as the concentration of at-home test results between November 2021 and February 2022.

Strengths

• Data originates from the authoritative State of California Department of Public Health (CDPH).
• Provides specific context on a major data revision, noting the exclusion of 17,467 at-home test cases.
• Clarifies the case definition, focusing on individuals with a positive antigen test.

Limitations

• Dataset is archived and no longer updated, limiting analysis to historical periods only.
• Excludes all probable case data from San Diego County, creating a geographic gap for statewide analysis.
• Data may be subject to retrospective adjustments, as noted for percentage changes in the first two weeks of a month.

Provenance

Source

State of California Department of Public Health (CDPH).

Collection Method

Aggregated from antigen test results reported to CDPH.

Time Range

Covers the COVID-19 pandemic period up to the end of the Public Health Emergency; specific dates not provided.

Freshness

Archived; last updated 2026-03-23, but reflects data collection prior to the end of the Public Health Emergency.

Geography

State of California, excluding San Diego County.