5/15/20 COVID-19 Brief: What is Serology Antibody Testing?

The WorkSTEPS team continues to carefully track what is happening with the COVID-19 pandemic.

A Message on COVID-19 from WorkSTEPS Chief Medical Officer Dr. Ben Hoffman:

Serology Antibody Testing – Q&A with Dr. Ben Hoffman

All employers are trying to figure out how to eliminate or reduce the risk of an infected employee from entering a worksite. One of the hotter topics among employers of late is serology testing (a.k.a., antibody testing or antibody blood testing). Employers have a lot of questions about whether, when and how they can use testing to improve, expedite and simplify return-to-work (RTW) decision-making. Additionally, there is a good bit of discussion in the media about testing, making it all the more difficult for employers to focus on meaningful information and actionable guidance.

So, we thought the best way to help our readers sort through the clutter would be a Q&A with Dr. Ben Hoffman. We’ve provided links along with some of Dr. Hoffman’s answers so you can dig more deeply on a particular topic if you like.

We hope your questions about Antibody Testing are answered below, but if not, feel free to let us know.

WorkSTEPS Brief: Let’s level-set here with a basic question: What is serology antibody testing, and what is does it tell us?

Dr. Ben Hoffman: Serology tests are used to determine if a person has been infected with the COVID-19 virus. When someone is infected with COVID-19, their body will respond by creating antibodies specifically designed to fight it. Serology tests look for those specifically designed antibodies in a person’s blood. If the antibodies are there, it means the person is sick/has been sick with COVID-19. Click here for more information about testing.

The Brief: If someone has antibodies, does that mean they are immune and can’t be infected with COVID-19 again?

Dr. Hoffman: We are hoping so, but we don’t really know. And even if the answer is “yes,” that antibodies do confer immunity to COVID-19, we don’t know for how long. Someday we will know for sure, but we just don’t know right now because the infection hasn’t been around long enough. And because we don’t know for sure, we can’t say things like: “Well, if you already had COVID-19, you don’t have to worry about getting it again.” It’s just one of the critical variables that requires that our prevention strategies be informed by the latest information and flexible to respond to changes in what we know.

The Brief: What is the role of serology testing in RTW determinations?

Dr. Hoffman: Well, that’s the million-dollar question at the moment. Ideally, employers can have access to serology testing that is affordable and reliably accurate so they can use test results as part of a clinical assessment process to make a well-informed RTW decision.

The Brief: It feels like there is a “but” coming…

Dr. Hoffman: Yes, more than one. And frankly we could fill a couple of pages with a long explanation, so let me try to boil it down. Because the regulatory environment around point-of-collection (POC) antibody testing was murky early on, lots of companies responded to the need and opportunity to provide testing, and the marketplace got flooded with tests. Since the “wild west” of the early weeks, guidance and protocols around obtaining Emergency Use Authorization (EUA) from the FDA has been made clearer. As a result, reputable labs are lining up to request EUA for their POC tests, but that process takes time.

So as it stands, we have a few POC Antibody Test brands that have been proven reliable and accurate, and we have a lot of parties (including health systems, states and the Federal Government) bidding for and buying up those tests. The tests that have not yet been evaluated under EUA may or may not be reliable and accurate, regardless of the manufacturers claims. Read more about the FDA’s Antibody Test policies here.

The Brief: So to be clear: 1) There are lots of POC antibody tests on the market right now; but 2) Only a few of them have been tested and proven to be reliable and accurate; and 3) there is a lot of competition among buyers bidding for that currently limited pool of Antibody Tests. Do I have that right?

Dr. Hoffman: Yes, that’s the picture at the moment.

The Brief: OK then, we’ve also heard concerns about how “accurate” even the FDA-approved tests are. What’s going on there?

Dr. Hoffman: Let’s start with the fact that no test is ever 100% accurate. Even if the test itself is perfect, there are other variables having to do with administration, handling of a sample, transportation… So, no test is ever perfect.

With that, the POC antibody tests that are being approved do a really good job identifying people who do have antibodies, and many of the tests report 97% specificity, which means that just 3% of tests will indicate people do have antibodies when they actually don’t have antibodies (3% false positive rate). Having said that, when a disease has low prevalence in a population, as is the case with COVID-19, even highly-accurate tests can have too many false positives and false negatives. Click here to learn more on the usefulness and limitations of serology testing.

So, the tests are good enough to provide valuable data that becomes part of a clinical assessment to determine whether someone can return to work. Testing is not meant to replace clinical judgement - only to inform it.

The Brief: Related to testing accuracy, we’re hearing some concerns about testing relative to EEOC and ADA liability. Any thoughts there?

Dr. Hoffman: The best I can do here is quote what our legal advisor Frank Alvarez has written in his firm’s blog recently. He writes: “the EEOC states employers may take steps to determine if employees entering the workplace have COVID-19 because an individual with the virus will pose a direct threat to the health of others. But, the EEOC notes that employers should ensure that the tests are “accurate and reliable.”

To “ensure that tests are “accurate and reliable’” is the key phrase. Now that the FDA has been clear in its EUA guidance, it seems prudent for employers to use EUA tests.

The Brief: So the obvious question then: If it’s too expensive to make serology testing part of a company’s RTW strategy, what should employers be doing?

Dr. Hoffman: For most of their employees, companies can use a symptom-based RTW protocol which says that ten days after the onset of symptoms, a person may return to work if they are free of fever and other symptoms without the use of symptom-reducing medications. I recommend readers ask for the symptom-based RTW flow chart we created (click here to request); it’s pretty straight-forward.

The Brief: You said “most employees;” what about the others?

Dr. Hoffman: Hospital workers and first responders are being monitored with testing more often due to the risks they take and the implications of serology testing. Other types of employers have workers that they determine to be critical infrastructure workers because of the nature of their function. And because such workers are critical to the operation, employers may decide that the added expense of quality serology testing is worth it. Just who is “critical” is really a business decision, based on an assessment of personnel that are critical for operations.

The Brief: As the supply of affordable, reliable and accurate tests increases, should employers plan to use them more?

Dr. Hoffman: That will be an ongoing business decision. Thoughtful companies will develop a sort of hierarchy around positions deemed to be “critical workers.” As quality tests become more affordable and easier to use, companies will use the tests more liberally to inform and expedite RTW decisions for more workers.

The Brief: Anything else to add?

Dr. Hoffman: The final point…and I say this probably 20 times a day to different customers…is that testing is just one filter in a system of filters a company needs to have in place. I wrote about this in more depth in a recent article, and another article highlighted the comprehensive guidance the CDC recently provided for the meat and poultry processing industry. Testing – no matter how well-done – will be imperfect, so companies need to commit to executing all the other filters as well: social distancing, barriers, disinfection, handwashing and mask-wearing.

The Brief: Thanks, Dr. Hoffman. Very helpful.

Dr. Hoffman: Thank you. I wish we had more definitive answers to some of your questions, but I think it’s good to understand what we don’t know so we can adapt our strategies.

Be well and stay safe.

Ben Hoffman, MD, MPH
Chief Medical Officer, WorkSTEPS


Area Reported Cases Deaths Recovered
Global 4,494,873 301,778 1,691,625
United States 1,443,946 86,244 312,513

Click here for full article.

While the focus has been on the new drugs to treat COVID-19, existing drug therapies have shown promise:

A triple-antiviral therapy regimen of interferon-beta1, lopinavir/ritonavir, and ribavirin shortened median time to COVID-19 viral negativity by 5 days in a small trial from Hong Kong.

In an open-label, randomized phase 2 trial in patients with mild or moderate COVID-19 infections, the median time to viral negativity by nasopharyngeal swab was 7 days for 86 patients assigned to receive a 14-day course of lopinavir 400 mg and ritonavir 100 mg every 12 hours, ribavirin 400 mg every 12 hours, and three doses of 8 million international units of interferon beta-1b on alternate days, compared with a median time to negativity of 12 days for patients treated with lopinavir/ritonavir alone (P = .0010), wrote Ivan Fan-Ngai Hung, MD, from Gleaneagles Hospital in Hong Kong, and colleagues.

The U.S. Food and Drug Administration has issued the first emergency use authorization (EUA) for a COVID-19 antigen test, a new category of tests for use in the ongoing pandemic. These diagnostic tests quickly detect fragments of proteins found on or within the virus by testing samples collected from the nasal cavity using swabs. The EUA was issued late Friday to Quidel Corporation for the Sofia 2 SARS Antigen FIA. This test is authorized for use in high and moderate complexity laboratories certified by Clinical Laboratory Improvement Amendments (CLIA), as well as for point-of-care testing by facilities operating under a CLIA Certificate of Waiver.

The U.S. Food and Drug Administration authorized the first diagnostic test with the option of using home-collected saliva samples for COVID-19 testing. Specifically, the FDA issued an emergency use authorization (EUA) to Rutgers Clinical Genomics Laboratory for their COVID-19 laboratory developed test (LDT), which had been previously added to the high complexity molecular-based LDT “umbrella” EUA, to permit testing of samples self-collected by patients at home using the Spectrum Solutions LLC SDNA-1000 Saliva Collection Device.

Once patients collect their saliva sample, they return it to the Rutgers Clinical Genomics Laboratory in a sealed package for testing.

The Rutgers Clinical Genomics Laboratory test is currently the only authorized COVID-19 diagnostic test that uses saliva samples to test for SARS-CoV-2, the strain of coronavirus that causes COVID-19. The test remains prescription only.

A new study offers a glimmer of hope in the grim fight against the coronavirus: Nearly everyone who has had the disease — regardless of age, sex or severity of illness — makes antibodies to the virus.

The study, posted online on Tuesday but not yet reviewed by experts, also hints that anyone who has recovered from infection may safely return to work — although it is unclear how long their protection might last.

Mitigation / Suppression:

Officials are under pressure to restart the economy, but many states are moving too quickly, researchers say. The costs may be measured in lost lives.

“We’re not reopening based on science,” said Dr. Thomas R. Frieden, a former director of the Centers for Disease Control and Prevention in the Obama administration. “We’re reopening based on politics, ideology and public pressure. And I think it’s going to end badly.”

Read the full NY Times article here

Dr. Anthony S. Fauci, the nation’s top infectious disease expert, said there was no chance of having a vaccine ready in time for the new school year in the fall. And he said the US was still far from the levels of testing and contact tracing needed to contain outbreaks.

If we do not respond in an adequate way when the fall comes, given that it is without a doubt that there will be infections that will be in the community, then we run the risk of having a resurgence,” Dr. Fauci said. “I would hope that by that time, in the fall, that we would have more than enough to respond adequately. But if we don’t, there will be problems.”

Read the full NY Times article here

Face Masks Against COVID-19: An Evidence Review:

A conservative assessment applied to the COVID-19 estimated R0 of 2.4 might posit 50% mask usage and a 50% mask efficacy level, reducing R0 to 1.35, an order of magnitude impact rendering spread comparable to the reproduction number of seasonal influenza. To put this in perspective, 100 cases at the start of a month becomes 31,280 cases by the month’s end (R0 = 2.4) vs. only 584 cases (R0 = 1.35). Such a slow-down in case load protects healthcare capacity and renders a local epidemic amenable to contact tracing interventions that can eliminate the spread entirely.

Access the full report - Face Masks Against COVID-19: An Evidence Review


CDC releases an update to its Interim Guidance for Businesses and Employers Responding to Coronavirus Disease 2019 (COVID-19), May 2020, Plan, Prepare and Respond to Coronavirus Disease 2019:

Summary of Changes to the Guidance as of May 6, 2020:

Updated strategies and recommendations for employers responding to COVID-19, including those seeking to resume normal or phased business operations:

  • Conducting daily health checks
  • Conducting a hazard assessment of the workplace
  • Encouraging employees to wear cloth face coverings in the workplace, if appropriate
  • Implementing policies and practices for social distancing in the workplace
  • Improving the building ventilation system

A table outlining the engineering controls, administrative controls, and personal protective equipment (PPE) that employers may use to help prevent the spread of COVID-19 in the workplace

Click here to review the full Summary of Changes to the Guidance

From screening and antibody testing of your employees to guidance on return-to-work to medical consulting and policy development, WorkSTEPS partners with your organization to support your response to the threat of COVID-19 in the workplace. Click here to learn more about our COVID-19 Services.

The Work From Home WorkSTEPS Medical Team:

Ben Hoffman, MD, MPH
Chief Medical Officer

Tony Nigliazzo, MD
Medical Director

Loraine Kanyare, MSN, MPH, RN
Director of Case Management

Robert L. Levitin, MD
Physician Consultant

Lynda Phillips, LVN
Nurse Case Manager

Codey Church, LVN
Nurse Case Manager

Kerry Womack, LVN
Nurse Case Manager

Chuck Reynolds
Strategic Communications Consultant

This Guidance (“Guidance”) is provided for informational and educational purposes only. It is not intended as Legal Advice or Medical Advice. Adherence to any recommendations included in this Guidance will not ensure successful diagnosis or treatment in every situation. Furthermore, the recommendations contained in this Guidance should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care nor exclusive of other methods of care reasonably directed to obtaining the same results. The ultimate judgment regarding the propriety of any specific therapy must be made by the physician and the patient in light of all the circumstances presented by the individual patient, and the known variability and biological behavior of the medical condition. Similarly, this Guidance is based on current advice, comments, and guidance from the EEOC, CDC and the CMS made publicly available. The ultimate judgement regarding the propriety of any specific employment action must be made by the company and attorney in light of all of the circumstances presented by the company, state and federal rules existing at the time and the then current state of the National Pandemic. This Guidance and its conclusions and recommendations reflect the best available information at the time the Guidance was prepared. The results of future studies or changes in rules, regulations or laws may require revisions to the recommendations in this Guidance to reflect new data. WorkSTEPS does not warrant the accuracy or completeness of the Guidance and assumes no responsibility for any injury or damage to persons or property arising out of or related to any use of this Guidance or for any errors or omissions.

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