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Coronavirus Disease 2019

Interim Guidelines for COVID-19 Antigen Testing in Skilled Nursing Facilitie


Interim Guidelines for COVID-19 Antigen Testing in Skilled Nursing Facilities

Summary of Recent Changes

10-16-20 Tier 3 has been added to include more frequent use of point-of-care antigen testing

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Background

Testing for SARS-CoV-2, the virus that causes COVID-19, is an important adjunct to infection control measures for preventing and controlling outbreaks in skilled nursing facilities (SNFs). The SARS-CoV-2 testing landscape is continually changing as additional tests receive an emergency use authorization (EUA) from the FDA. Technology to conduct molecular, antigen, and serology tests is now available and additional technologies are anticipated. The availability of evidence regarding the performance of these different tests as well as guidelines for their best use in different populations is still limited.

Overview of Current SARS-CoV-2 Tests

Only molecular and antigen tests are recommended to diagnose current SARS-CoV-2 infection. These viral tests detect the SARS-CoV-2 virus directly either by detecting viral RNA (molecular) or viral surface proteins (antigen). Serologic tests cannot be used alone to diagnose an active SARS-CoV-2 infection but may be used to help support or establish a diagnosis in limited circumstances.

Molecular tests are currently the most accurate tests for diagnosing COVID-19. Molecular tests detect the unique genetic sequence of the SARS-CoV-2 virus by using nucleic acid amplification (NAA) technology such as reverse transcription polymerase chain reaction (RT-PCR). Laboratory turn-around time for PCR test results should be less than 48 hours, however results can be delayed if laboratories are experiencing high volumes.

Antigen tests detect the presence of SARS-CoV-2 viral surface proteins. The main advantages of antigen tests are that results are available within 15-30 minutes, they are relatively simple to perform, and they are less expensive than RT-PCR tests. The currently available EUA authorized SARS-CoV-2 antigen tests are all approved as POC tests for settings with a CLIA waiver and they are intended for use on symptomatic persons within 5-12 days of symptom onset (the number of days varies by manufacturer).

Clinicians should remember that molecular and antigen test accuracy is dependent on many factors including the test technology, specimen collection and handling, pretest clinical probability of disease, community prevalence of disease, and the specific characteristics of the assay.

See LAC DPH COVID-19 Provider Testing webpage for more information.

Using Antigen Tests in Skilled Nursing Facilities

The best use of POC COVID-19 antigen testing in nursing homes is still being defined. Antigen tests can augment other testing efforts, especially in settings where RT-PCR testing capacity is limited or testing results are delayed. Rapid antigen tests should add both clinical and infection control value as they can rapidly “rule in” persons with SARS-CoV-2 infection.

There is limited data to guide the use of antigen tests for screening asymptomatic persons. Interim antigen testing guidelines released by the CDC and CDPH outline a role in screening asymptomatic residents and staff in nursing homes as a strategy to rapidly detect and triage asymptomatic or pre-symptomatic cases in a vulnerable congregate setting.

This document is meant to provide clinicians working in nursing homes with guidelines to help them determine the best use of different viral tests that they can apply to the local testing conditions for each facility. 

Note: Testing for COVID-19 by using PCR is preferred. The recommendations below are intended to provide guidance on how to incorporate antigen testing when timely PCR testing is not available. See the COVID-19 Testing section of the LAC DPH Guidelines for Preventing and Managing COVID-19 in SNFs for testing requirements and resources. Facilities experiencing short term PCR testing shortages may contact LAC DPH at (213)-240-7941.

Recommended Testing Strategies
(Listed in descending order of preference)

Patient Type

Testing strategy

Response

PCR testing is easily accessible and results are available within 48 hours

All residents and Staff

Standard PCR testing per LAC DPH SNF Guidelines1

Isolate/quarantine/cohort per guidelines.

Use of POC Ag tests for response/outbreak testing; consider when PCR results not available within 48 hours2

Symptomatic resident

POC Ag test positive no additional testing

Isolate (Red Cohort).

POC Ag test negative confirm with PCR

Quarantine (Yellow Cohort) pending PCR confirmation

  • If PCR positiveRed Cohort 
  • If PCR negativeGreen Cohort with droplet precautions until after resident is clinically improved and 24 hours after resolution of fever.

Asymptomatic resident

POC Ag test positive confirm with PCR

Quarantine (Yellow Cohort) pending PCR confirmation

  • If PCR positiveRed Cohort
  • If PCR negativeGreen Cohort

POC Ag test negative confirm with PCR

Green Cohort Move to Red Cohort if PCR positive.

Symptomatic staff

POC Ag test positive no additional testing

Restrict from work. Follow return to work guidelines

POC Ag test negative confirm with PCR

Restrict from work pending PCR result

  • if PCR is positive, continue work restriction and follow return to work guidelines
  • If PCR is negative, staff may return to work when clinically improved and 24 hours after resolution of fever.

Asymptomatic staff

POC Ag test positive confirm with PCR

Restrict from work pending PCR result

  • If PCR is positive, continue work restriction and follow return to work guidelines
  • If PCR is negative, staff may return to work

POC Ag test negative Confirm with PCR

No work restriction restrict if PCR positive.

Use of POC Ag tests for Screening-Only (Not indicated for response/outbreak testing )

Asymptomatic resident

POC Ag test positive confirm with RT-PCR

Quarantine (Yellow Cohort) pending confirmatory RT-PCR

  • RT-PCR positiveRed Cohort
  • RT-PCR negativeGreen Cohort

POC Ag test negative

Stay in Green Cohort. Continue serial screening.

Asymptomatic staff

POC Ag test positive confirm with RT-PCR

Restrict from work pending confirmatory RT-PCR. If restriction would result in a staff shortage, staff member may work in Red Cohort pending PCR confirmation

  • RT-PCR negative, return to work.
  • RT-PCR positive, continue work restriction and follow return to work guidelines

POC Ag test negative 

Continue serial screening.

  1. LAC DPH Guidelines for Preventing & Managing COVID-19 in Skilled Nursing Facilities.
  2. If PCR testing is insufficient to meet testing needs for all staff and residents, then prioritize residents for PCR testing.
Reporting Results

All Facilities must have a CLIA Certificate of Waiver to use POC devices. Facilities must report data for all testing completed on positive test results for each individual (staff and resident) tested to LAC DPH. This data must be reported within 24 hours of test completion, on a daily basis. For reporting guidelines, please refer to http://publichealth.lacounty.gov/acd/ncorona2019/reporting.htm. All positive tests must be reported using the Medical Provider COVID-19 Report form. Complete all sections and submit by secure e-mail to Covid19@ph.lacounty.gov (preferred) or by fax to: (310) 605-4274.

Related Resource

Frequently Asked Questions: COVID-19 Testing at Skilled Nursing Facilities/ Nursing Homes

Coronavirus Disease 2019 (COVID-19) Mitigation Plan Recommendations for Testing of Health Care Personnel (HCP) and Residents at Skilled Nursing Facilities (SNF): https://www.cdph.ca.gov/Programs/CHCQ/LCP/Pages/AFL-20-53.aspx



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