This webpage is available for historical purposes. It is no longer being updated and may not reflect current guidance. For current COVID-19 testing guidance please visit CDC Overview of Testing for SARS-CoV-2 and CDPH COVID-19 Testing Guidance.
Summary of Recent Changes
Significant changes to this guidance include the following:
These guidelines are intended for use by healthcare providers, public health professionals, and those organizing and implementing testing in non-healthcare settings. Information for the general public is available at ph.lacounty.gov/covidtests (English) and ph.lacounty.gov/covidpruebas (Spanish).
Currently FDA-authorized viral tests for SARS-CoV-2 (NAATs or antigen) can be used for both diagnostic and screening* purposes. When choosing the type of test to use and when interpreting test results, it is important to consider the purpose of the testing (diagnostic or screening), the test performance characteristics (sensitivity and specificity), and the pre-test probability of infection. For a detailed discussion of COVID-19 test types, their use, and interpretation, see the COVID-19 Testing page.
*Regardless of FDA authorization, for the duration of the public health emergency, CMS has indicated all SARS-CoV-2 diagnostic tests can be used on asymptomatic people. Health plans are required to pay for COVID-19 testing for their enrollees whether they are symptomatic or asymptomatic.
The goals of diagnostic testing are to identify persons actively infected with SARS-CoV-2 virus (based on symptoms or exposure) to help guide clinical and infection control decisions.
Diagnostic testing is indicated when infection is suspected, such as when the person:
Nucleic acid amplification tests (NAATs) or antigen tests can be used for diagnostic testing. Negative results from less sensitive tests (e.g., antigen tests, some NAATs), should be considered presumptive and confirmation with a standard laboratory-based NAAT test (e.g., RT-PCR) is recommended if important for clinical management or infection control decisions. When testing symptomatic persons who have had a positive viral test in the past 90 days antigen tests are preferred. Per the CDC, a positive antigen test may be more be more consistent with active infection.
Screening testing is intended to identify people with COVID-19 who have no signs or symptoms of COVID-19 and no known or suspected exposure to SARS-CoV-2.
The rationale for screening testing is to identify persons with pre-symptomatic or asymptomatic SARS-CoV-2 infection in order to prevent additional spread of the virus.
Both types of viral test (NAAT or antigen) can be used for screening testing. Any patient with a positive viral screening test should be treated as a case and isolated. Decisions regarding confirmatory testing should be based on the pre-test probability of infection and the specificity of the test used. Confirmatory testing, ideally with a laboratory based NAAT, is recommended for persons who screen positive with a rapid antigen test. See interpretation of NAAT and antigen test sections for more information.
Post Omicron surge, LAC DPH is using the CDC COVID-19 Community Levels to assess the impact of COVID-19 illness on health and healthcare systems across the county and adopt corresponding prevention strategies, including screening testing. Priority sector screening requirements and recommendations vary by the COVID-19 Community Level. The priority sectors with screening testing recommendations by Community Level are SNFs, K-12 and early childhood education, shelters for persons experiencing homelessness, worksites, healthcare settings.
To see the current LA County Community Level and the corresponding priority sector screening testing response visit LA County Post-Surge Dashboard. Screening recommendations are also discussed in sector-specific guidelines.
Additional screening recommendations include:
Screening testing is not recommended for:
All healthcare providers and systems should be able to provide their patients with timely access to SARS-CoV-2 diagnostic testing when indicated. See Health Officer Order: Access to Diagnostic Testing Through Healthcare Facilities for more information. Organizations that need assistance to identify a suitable laboratory provider are encouraged to view the resources in the laboratories section below.
LA County Guide to Laboratories Providing COVID-19 Testing Services Updated Reference Guide This document provides an overview of some of the labs offering testing services to LA County providers and residents.
California Testing Task Force Lab List The Testing Task Force is maintaining a list of labs that have met certain criteria for readiness and can receive samples for RT-PCR COVID testing.
All laboratories (regardless of their location) that test Los Angeles County residents must register with CDPH.
Federal law requires all plans to provide coverage of COVID-19 testing
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