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Coronavirus Disease 2019

LAC DPH Testing Guidelines & Resources

LAC DPH SARS-CoV-2 Testing Guidelines

Summary of Recent Changes
Significant changes to this guidance include the following:


  • Revised screening testing section to reflect new and updated screening requirements and recommendations.

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.

Diagnostic testing

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:

  • Has signs or symptoms of COVID-19
    Individuals who have symptoms consistent with acute COVID-19 should be tested for SARS-CoV-2 infection regardless of vaccination status or recent history of previous infection.
  • Is a close contact to a confirmed case, regardless of vaccination status
    Testing is not recommended for asymptomatic close contacts who have recovered from laboratory-confirmed COVID-19 within the past 3 months (90 days).
  • Is part of an outbreak investigation and response and/or case investigation
    Testing is recommended regardless of vaccination status. Investigations may include testing of asymptomatic persons with recent history of previous infection as directed by Public Health.

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.

Screening testing

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. This is different from surveillance testing, which is intended to characterize the incidence and prevalence of disease and is performed on de-identified specimens, and thus, results are not linked to individual people.

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 within specific settings. With the presence of the very infectious Delta variant in the context of highly effective COVID-19 vaccines, there are many new and updated screening requirements.

Requirements and Recommendations

Screening testing is required*:

*This list is not inclusive of all required screening testing. There are many additional settings or facilities that have their own screening testing requirements.

Screening testing is recommended:

  • For persons who are not fully vaccinated in the following settings
  • In schools
    • Routine screening testing of staff and students that are not fully vaccinated is recommended as an important part of identifying cases early in the school setting so that measures can be taken to prevent further transmission given the low vaccination rate in children.
    • When community transmission rates are high, surveillance testing that includes fully vaccinated staff and students in schools is appropriate if testing capacity allows.
  • Before and after travel for the following persons
    • People who are not fully vaccinated, testing is recommended 1-3 days prior to and 3-5 days after domestic travel.
    • 3-5 days after international travel, regardless of vaccination status.

Note: organizations conducting screening testing should have a mechanism to confirm positive results in asymptomatic persons with no known exposure when the probability of infection is low. See interpretation of NAAT and antigen test sections for more information.

Screening testing is not recommended for:

  • Fully vaccinated persons unless they fall into one of the categories listed above
    To date, all published literature indicate that currently authorized vaccines are highly effective at preventing serious illness and death due to COVID-19 infection and are effective at preventing most transmission. Fully vaccinated people with no COVID-19-like symptoms and no known exposure do not need to be tested for SARS-CoV-2 infection unless they fall into one of categories listed above.
  • Persons who have recovered from laboratory confirmed COVID-19 within the past 90 days and are asymptomatic
    Recently infected persons are known to shed virus for up to 90 days after recovery and reinfection is unlikely to occur during this period. To avoid false positives due to detection of non-infectious viral particles, provided they remain asymptomatic, they should not be part of screening programs until at least 90 days after the onset of initial illness (or after the date of first positive viral test if they never had symptoms).

Access to Diagnostic Testing Through Healthcare Facilities

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.

Laboratory Information

Laboratories Providing Diagnostic Testing

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.

Laboratory Registration Requirements

All laboratories (regardless of their location) that test Los Angeles County residents must register with CDPH.

Coverage of COVID-19 Testing

Federal law requires all plans to provide coverage of COVID-19 testing

  • Federal guidance: FAQs About Families First Coronavirus Response Act and Coronavirus Aid, Relief, and Economic Security Act Implementation (February 26, 2021).

Zero Cost Sharing

  • All commercial and Medi-Cal health plans in California must provide COVID-19 testing and visits with zero cost sharing. Health plans must cover the testing whether the person is symptomatic or asymptomatic and regardless of whether the person has had recent known or suspected exposure to COVID-19. See Department of Managed HealthCare All Plan Letter (7-26-21).

Testing Options for Employers Working to Meet New State Requirements for Testing in Unvaccinated Individuals

New State and LA County Health Officer Orders require vaccinations or regular (weekly or biweekly COVID-19 testing) for unvaccinated employees in various settings, including health care settings and schools. These require employers and facilities to test and monitor their workforce members. This document details options for employers to meet these requirements.

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  • Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.

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