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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.

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.

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 as soon as possible regardless of vaccination status or recent history of previous infection.
  • Is a close contact to a confirmed case, regardless of vaccination status
    Testing is recommended 5-7 days after the last contact with case. For details, refer the close contact to Quarantine and Other Instructions for Close Contacts: ph.lacounty.gov/covidquarantine
    Testing is not recommended for asymptomatic close contacts who have recovered from 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. 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

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. With the presence of the very infectious Delta variant, the threat of the new Omicron variant, and concerns about another winter surge, as well as the widespread availability of viral tests, screening requirements and recommendations have been updated.

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.

Screening testing is not recommended for persons who have recovered from laboratory confirmed COVID-19 within the past 90 days, unless they develop symptoms of COVID-19.

Requirements and Recommendations

Screening testing is required*:

  • Workers who are not fully vaccinated in many settings including but not limited to healthcare, high-risk congregate settings (i.e., homeless shelters, correctional facilities, and detention centers), and K-12 schools. The frequency of testing depends on the setting.
  • All skilled nursing facility (SNF) employees, contractors, and residents, regardless of vaccination status. The required weekly screening has been expanded to SNF residents and fully vaccinated staff at facilities with high vaccination coverage. This requirement is effective December 15, 2021, to January 31, 2022. See Health Officer Order.
  • All general visitors to indoor portions of SNFs, regardless of vaccination status. This requirement is effective December 15, 2021 to January 31, 2022. See Health Officer Order.
  • Youth sports athletes and staff participating in moderate- and high-risk sports. Weekly screening testing is required for athletes and staff who are not fully vaccinated who participate in moderate- and high-risk sports organized by youth sports leagues, including school sports teams. In addition, fully vaccinated youth must also participate in weekly screening testing if they are participating in an indoor moderate-/high-risk sport where masks are not always worn by the team.
    Note: For children under 12 years of age playing outdoor moderate- and high-risk sports in organized sports leagues, weekly screening testing is recommended but not required. See Protocol for Organized Youth Sports.
  • International travelers, regardless of vaccination status, prior to boarding a flight bound for the United States, (screening is not required for persons with proof of recovery from laboratory confirmed COVID-19 in the past 90 days).
  • Visitors who are not fully vaccinated prior to entry into certain settings, including but not limited to indoor and outdoor mega-events, intermediate care facilities, and juvenile detention facilities, indoors and outdoors at adult correctional and detention centers, and as required by certain businesses and venues. For more information see ph.lacounty.gov/PublicSettings.

*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 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. (Teachers that are not fully vaccinated are required to participate in regular screening testing).
    • When community transmission rates are high, screening testing that includes fully vaccinated staff and students in schools is appropriate if testing capacity allows.
  • Before and after travel
    • Testing is recommended 1-3 days prior to domestic travel regardless of vaccination status.
    • Testing is recommended 3-5 days after return to LA County from international travel, regardless of vaccination status.
    • See LAC DPH Travel Advisory for the most current recommendations.
  • Before and after gatherings or events.
    • Testing is recommended prior to participating in indoor events with people from other households regardless of vaccination status, especially if there are persons at risk of severe complications from COVID-19. This is particularly important if the individual is not vaccinated but also adds an extra layer of protection for fully vaccinated attendees.
    • Testing is recommended after participating in gatherings or events with large numbers of people, especially if indoors.

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:

  • Persons who have had a positive viral COVID-19 test within the past 90 days and are asymptomatic
    Recently infected persons are known to continue to test positive for up to 90 days after recovery. 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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