410 - Healthcare Personnel (HCP) & COVID – A Refresher: Return to Work, Asymptomatic Exposure, False Positive Home Tests

From the CDC and a Refresher

1) Return to Work for Healthcare Workers After COVID-19 Infection

With the uptick in COVID-19 infections due to the delta variant, it is important to recall the CDC guidance regarding decisions about return to work for healthcare personnel (HCP) after testing positive for COVID. While ultimate decisions should be made in the context of local circumstances, the CDC provides some helpful guidance.

In general, a symptom-based strategy should be used as described below. The time period used depends on the HCP’s severity of illness and if they are severely immunocompromised. For most, a test-based strategy is not recommended because, in the majority of cases, it results in excluding from work HCP who continue to shed detectable SARS-CoV-2 RNA but are no longer infectious. One notable exception would be the HCP who is severely immunocompromised. Under such circumstances, consultation with a local or regional infectious disease specialist is recommended.

The symptom-based criteria for return to work includes the following:

• HCP who was asymptomatic throughout their infection and are not severely immunocompromised:
  • At least 10 days have passed since the date of their first positive viral diagnostic test.
• HCP with mild to moderate illness who are not severely immunocompromised:
  • At least 10 days have passed since symptoms first appeared and
  • At least 24 hours have passed since last fever without the use of fever-reducing medications and
  • Symptoms (e.g., cough, shortness of breath) have improved
• HCP with severe to critical illness or who are severely immunocompromised:
  • At least 10 days and up to 20 days have passed since symptoms first appeared and
  • At least 24 hours have passed since last fever without the use of fever-reducing medications and
  • Symptoms (e.g., cough, shortness of breath) have improved
  • Consider consultation with infection control experts

If a test-based strategy is utilized, consultation with an occupational medicine specialist is recommended. The criteria for the test-based strategy are:

• HCP who are not symptomatic:

• Results are negative from at least two consecutive respiratory specimens collected ≥24 hours apart (total of two negative specimens) tested using an FDA-authorized laboratory-based NAAT to detect SARS-CoV-2 RNA.

• HCP who are symptomatic:

• Resolution of fever without the use of fever-reducing medications and
• Improvement in symptoms (e.g., cough, shortness of breath), and
• Results are negative from at least two consecutive respiratory specimens collected ≥24 hours apart (total of two negative specimens) tested using an FDA-authorized laboratory-based NAAT to detect SARS-CoV-2 RNA.

Mark’s Comments:

The CDC notes in their guidance that maintaining appropriate staffing in healthcare facilities is essential to providing a safe work environment for HCP and safe patient care. They predicted (and we are experiencing) that as the COVID-19 pandemic progresses, staffing shortages would occur due to HCP exposures, illness, or need to care for family members at home. Though we were “prepared” for this, the extent in many practices and other healthcare settings has been unprecedented. It is therefore notable that the CDC indicates that one mitigation strategy could be considerations for permitting HCP to return to work without meeting all return-to-work criteria above.

In case you were wondering, astute readers will note that the general recommendations for both the symptom-based and test-based strategy are identical to the return-to-work guidance for non-HCP (though formatted differently). In that guidance, the CDC explicitly states that employers should not require a sick employee to provide a negative COVID-19 test result or healthcare provider’s note to return to work. 

References:

• CDC Return to Work Criteria for Healthcare Personnel with SARS-CoV-2 Infection (Interim Guidance). Updated 2 June, 2021. Link
• CDC Ending Home Isolation for Persons with COVID-19 Not in Healthcare Settings. Updated 18 February 2021. Link

From the CDC and a Refresher

2) Work Restrictions for HCP With Potential COVID Exposure

The CDC guidance for asymptomatic healthcare personnel HCP with potential COVID exposure was updated in March to include vaccination status and is intended to assist with assessment of risk and application of work restrictions for those who were in the presence of someone with confirmed SARS-CoV-2. The guidance clarified that in general, asymptomatic HCP who are fully vaccinated and have a higher-risk exposure as described in this guidance do not need to be restricted from work.

Unvaccinated HCP with prolonged exposure (< 6 feet for > 15 minutes) and not wearing a respirator or facemask OR not wearing eye protection if the person with SARS-CoV-2 infection was not wearing a cloth mask or facemask OR not wearing all recommended PPE (ie: gown, gloves, eye protection, respirator) while performing an aerosol-generating procedure:

• Exclude from work for 14 days after last exposure
• Advise HCP to monitor themselves for fever or symptoms consistent with COVID-19
• Any HCP who develops fever or symptoms consistent with COVID-19 should immediately contact their established point of contact (e.g., occupational health program) to arrange for medical evaluation and testing

Vaccinated HCP or HCP other than those with exposure risk described above (regardless of PPE status):

• No work restrictions
• Follow all recommended infection prevention and control practices, including wearing a facemask for source control while at work, monitoring themselves for fever or symptoms consistent with COVID-19 and not reporting to work when ill, and undergoing active screening for fever or symptoms consistent with COVID-19 at the beginning of their shift.
• Any HCP who develops fever or symptoms consistent with COVID-19 should immediately self-isolate and contact their established point of contact (e.g., occupational health program) to arrange for medical evaluation and testing.

Mark’s Comments:

As circumstances rapidly change in the face of the COVID Delta variant and cases increase again, decisions regarding the management of COVID exposures for HCP will certainly be influenced by local and regional as well as personal circumstances.

It also appears the CDC is continuing to be challenged to keep up with the swiftly moving changes. I was surprised to read the following CDC guidance regarding “Communal Activities within the Healthcare Setting:” While I would love for this to be our present reality, this doesn’t seem wise in the face of the highly transmissible and rapidly spreading delta variant.

“In general, fully vaccinated HCP should continue to wear source control while at work. However, fully vaccinated HCP could dine and socialize together in break rooms and conduct in- person meetings without source control or physical distancing. If unvaccinated HCP are present, everyone should wear source control and unvaccinated HCP should physically distance from others.” (2^nd Reference)

And this recently published guidance from the CDC for those who have been vaccinated from the 3^rd reference seems to contradict the guidance from the information above, specifically with regard to testing.

“If you’ve had close contact with someone who has COVID-19, you should get tested 3-5 days after your exposure, even if you don’t have symptoms. You should also wear a mask indoors in public for 14 days following exposure or until your test result is negative. You should isolate for 10 days if your test result is positive.” (3^rd Reference)

References:

• CDC: Interim Guidance for Risk Assessment and Work Restrictions for Healthcare Personnel with Potential Exposure to SARS-CoV-2. Updated 11 March, 2021. Link
• CDC: Updated Healthcare Infection Prevention and Control Recommendations in Response to COVID-19 Vaccination. Updated 27 April, 2021. Link
• CDC: When You’ve Been Fully Vaccinated: How to Protect Yourself and Others. Updated 27 July, 2021. Link

From the World of “You Just Can’t Make This Stuff Up”

3) Creating False “False Positive” COVID-19 At Home Tests

Some persons have figured out how to use soft drinks and other liquids to creative false positive results on some at home COVID-19 rapid test. Videos uploaded to social medial under the search term #fakecovidtest have been viewed millions of times and these videos were removed from the social media platform TikTok at the beginning of July for promoting false content. Many of these videos were originating in the United Kingdom, where since March schools have been asking students without symptoms to test at home twice weekly. A positive test can result in an entire class having to isolate at home.

This phenomenon led researchers at the University of Liverpool to study this in more detail. Their recently posted research (not peer reviewed) found that the process of applying certain substances to the test swabs can indeed produce false positive results for the COVID-19 home tests that use lateral flow device (LFD) immunoassay technology. While artificial sweeteners produced negative results, 10 of 14 soft drinks, notably those containing citric or ascorbic acid, produced positive or weakly positive results.

They concluded that soft drinks misused as analyte can produce false “false positive” SARS-CoV-2 LFD results, and based on their findings recommended that home testing is best done first thing in the morning, prior to any food or drink, and under supervision where possible.

Mark’s Comments:

While PCR tests remain the gold standard for SARS-CoV-2 detection, these so-called rapid COVID-19 tests that employ lateral flow technology can return a result in 30 minutes or less. This finding is not a flaw of the test, but rather a misuse of it, and one that can have significant public health implications as we approach the start of in-person school once again.

It should be noted that lateral flow tests that have received emergency use authorization (EUA) in the US for over-the-counter at-home testing include Ellume COVID-19 Home Test and the Abbott BinaxNOW COVID-19 Antigen Self Test.

Reference:

Oni, L. et al. (2021). Soft drinks can be misused to give false positive SARS-CoV-2 lateral flow device results. Medrxiv. Posted 5 July 2021. Link

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Mark and John

Carilion Clinic Department of Family and Community Medicine

Feel free to forward Take 3 to your colleagues. Glad to add them to the distribution list.

Email: mhgreenawald@carilionclinic.org