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COVID-19 Health Alert # 22:
Revised guidance for the use of rapid, point of care tests in supporting return to work for quarantined healthcare personnel
Bureau of Communicable Diseases, November 30, 2020
Summary
- DHS has previously provided guidance for staffing crises in healthcare settings, whereby healthcare personnel (HCP) who are in quarantine due to close contact with a person with COVID-19 may return to work under a protocol of enhanced precautions and serial testing.
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The guidance shared on October 12 (HAN #18), indicated that a serial testing protocol with either a molecular test or a rapid antigen test could reduce the risk associated with HCP returning to work during the quarantine period. However, newer data suggest that the sensitivity of rapid antigen tests may be unacceptably low when used for screening asymptomatic individuals.
- DHS now recommends that lab-based molecular diagnostic tests be used preferentially for return-to-work protocols for quarantined HCP. Rapid point-of-care tests may be used if access to lab-based tests with acceptable turnaround time is limited. If rapid tests are used, the frequency of testing should be every day of work, rather than every 72 hours, and ideally at the beginning of every scheduled shift.
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HCP who develop symptoms during their quarantine period and those who test positive by antigen or molecular test should be excluded from work until they meet criteria for discontinuation of isolation.
Dear Colleagues,
During staffing crises brought on by the surge of COVID-19 hospitalizations, some health care personnel (HCP) who have been exposed to SARS-CoV-2 have been asked to report for duty during their 14-day quarantine period. Because of the risk of asymptomatic and presymptomatic transmission, HCP who engage in patient care during the incubation period pose a risk of spreading the disease in the workplace before they know they are infected. Serial testing as a condition of returning to work may mitigate, but not completely eliminate, this risk.
New data show rapid antigen tests have low sensitivity in asymptomatic individuals
DHS recently collaborated with CDC investigators to evaluate the performance of one of the available rapid point-of-care antigen tests, the Quidel Sofia SARS Antigen Fluorescent Immunoassay (FIA), in comparison with molecular diagnostic tests. The results, shown in Table 1, indicate that in the absence of symptoms the sensitivity of the test is estimated to be 41.2%.
Table 1. Performance Characteristics of Quidel Sofia in Symptomatic and Asymptomatic People (N=1,098)†
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Test Characteristics
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Asymptomatic People
% (95% CI)
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Symptomatic People
% (95% CI)
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Sensitivity
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41.2 (18.4–67.1)
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80.0 (64.4–90.9)
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Specificity
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98.4 (97.3–99.1)
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98.9 (96.2–99.9)
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Positive predictive value
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33.3 (14.6–57.0)
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94.1 (80.3–99.3)
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Negative predictive value
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98.8 (97.8–99.4)
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95.9 (92.0–98.2)
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† Unpublished data, Wisconsin DHS and CDC
While there remains a need for additional research to clarify the sensitivity of other rapid antigen platforms in a variety of clinical and surveillance settings, the performance characteristics of all the rapid tests are believed to be comparable. This includes rapid antigen tests and rapid point-of-care molecular tests, such as the Abbott ID NOW COVID-19 test.
Use of rapid tests for quarantined healthcare personnel
Minimizing the risk of SARS-CoV-2 transmission in healthcare settings is of the utmost importance. Outside of critical staffing shortages, HCPs who have been in close contact with a person with COVID-19 should be quarantined and excluded from work for the duration of the 14-day incubation period of the virus. As described in previous DHS guidance (HAN #18), if 14-day quarantine of HCP will adversely impact patient care, healthcare facilities should ensure the following protections are in place before allowing exposed HCP to return to work:
- HCP should be asymptomatic.
- HCP should report temperature and absence of symptoms before each shift.
- HCP should wear a facemask at all times for source control while in the facility. A higher level of personal protective equipment should be used when indicated.
- HCP, to the extent possible, should minimize contact with other persons outside of work and continue quarantining when at home.
- Asymptomatic HCP should only be allowed to work in patient care areas if they have had a recent COVID-19 test, which should be collected and resulted as soon as possible before reporting for duty. At a minimum:
- Molecular tests (PCR) should be done every 48-72 hours during the quarantine period.
- If using point-of-care tests they should be done each day of work, ideally immediately before every patient care shift.
Use of rapid tests in non-healthcare settings
Rapid point-of-care antigen and molecular tests are useful tools for providing rapid diagnostic information in patients with symptoms of COVID-19. Because of their lower cost and relative ease of implementation, these tests are increasingly being used for screening and surveillance in settings where frequent testing is needed but the availability of lab-based testing is inadequate. For example, antigen tests are being used for routine screening of staff in skilled nursing facilities, in accordance with CMS recommendations, and on college and university campuses. DHS supports the use of rapid tests in these settings, and urges organizations to use a two-test strategy when indicated to improve the reliability of the test results. Specifically, DHS recommends:
- For individuals without symptoms of COVID-19, positive tests should be followed by a second test to lower the likelihood of false positive results.
- For individuals with symptoms of COVID-19, negative tests should be followed by a second test to lower the likelihood of false negative results.
Sincerely,
Ryan Westergaard, MD, PhD, MPH
Chief Medical Officer and State Epidemiologist for Communicable Diseases
Wisconsin Department of Health Services
About the COVID-19 Health Alert Network
The content of this message is intended for public health and health care personnel and response partners who have a need to know the information to perform their duties. The HAN will be the primary method for sharing time-sensitive public health information with clinical partners during the COVID-19 response. Health care providers and other officials can subscribe and unsubscribe using their preferred email address at the DHS COVID-19 website.
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