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Clinical Laboratories and Pathology Groups

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Clinical Laboratories and Pathology Groups

Hosted by Robert Michel
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Immunocompromised Patients with COVID-19 May Remain Infectious for Much Longer than Previously Thought

Clinical laboratory professionals should note that one case study describes a COVID-positive cancer patient shedding infectious particles for five months, which is much longer than expected

Just when researchers start believing they understand COVID-19 infections, something happens that reveals there is still more to learn. These additional findings are relevant for clinical laboratory managers and pathologists because the new insights often may play a role in how SARS-CoV-2 results should be interpreted for individual patients.

Researchers recently described a case where, in February, a 71-year-old woman underwent surgery related to her 10-year battle with cancer. While she was in the hospital, she was found to be positive for the SARS-CoV-2 coronavirus, though she showed no respiratory or systemic symptoms. Nevertheless, the hospital isolated her and monitored the infection.

To everyone’s surprise, the patient remained positive for five months. She underwent 15 COVID-19 tests from various diagnostics companies, as well as receiving two doses of convalescent plasma therapy, but she remained positive for the coronavirus into June.

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) wanted to know why. They conducted a study on the woman, which they later published in the journal Cell, titled, “Prolonged Infectious SARS-CoV-2 Shedding from an Asymptomatic Immunocompromised Individual with Cancer.”

In their published study, they wrote, “Although it is difficult to extrapolate from a single individual, our data suggest that long-term shedding of infectious virus may be a concern in certain immunocompromised people. Given that immunocompromised individuals could have prolonged shedding and may not have typical symptoms of COVID-19, symptom-based strategies for testing and discontinuing transmission-based precautions, as recommended by the Centers for Disease Control and Prevention (CDC), may fail to detect whether certain individuals are shedding infectious virus.”

Clinical laboratory professionals and pathologists will find it significant that patients with major health conditions may be shedding viral material for weeks longer than originally thought. This is relevant because it may be prudent to COVID test patients who present with compromised immune systems, and who are asymptomatic, and then repeat that testing at appropriate intervals.

The graphic above taken from the NIAID study
The graphic above taken from the NIAID study shows how long it took for the SARS-CoV-2 coronavirus to clear the 71-year-old immunocompromised cancer patient’s system, and at which points the convalescent plasma doses were administered. (Graphic copyright: National Institute of Allergy and Infectious Diseases.)  

Immunocompromised Patients May Handle COVID-19 Differently

The NIAID researchers believe the reason the patient continued to shed infectious virus for so long was because she was immunocompromised. They wrote, “Many current infection control guidelines assume that persistently PCR-positive individuals are shedding residual RNA and not infectious virus, with immunocompromised people thought to remain infectious for no longer than 20 days after symptom onset. Here we show that certain individuals may shed infectious, replication-competent virus for much longer than previously recognized. Although infectious virus could be detected up to day 70, sgRNA, a molecular marker for active SARS-CoV-2 replication, could be detected up until day 105.”

In the United States, some three million people have compromised or weakened immune systems. This is a significant population, Science Alert reported.

“As the virus continues to spread, more people with a range of immunosuppressing disorders will become infected, and it’s more important to understand how SARS-CoV-2 behaves in those populations,” Vincent Munster, PhD, Chief, Virus Ecology Unit at the National Institute of Allergy and Infectious Diseases and co-author of the NIAID study, told Science Alert.

The NIAID study findings match knowledge about other coronaviruses. For example, Science Alert reported that immunocompromised people with Middle East Respiratory Syndrome (MERS) have been shown to shed common seasonal coronaviruses for up to a month following infection.

Asymptomatic Patients Are a Mystery

There is still much that is unclear about asymptomatic patients. A paper published in JAMA, titled, “Clinical Course and Molecular Viral Shedding Among Asymptomatic and Symptomatic Patients with SARS-CoV-2 Infection in a Community Treatment Center in the Republic of Korea,” questioned the viral load differences in patients who tested positive but had no symptoms compared to those who were symptomatic.

That study included 303 patients, of which 193 were symptomatic. During the course of the study, 21 of the asymptomatic patients developed symptoms, however, the viral load was similar in all of the patients, regardless of symptoms.

“Isolation of asymptomatic patients may be necessary to control the spread of SARS-CoV-2,” concluded the JAMA researchers. But how long should asymptomatic patients remain isolated?

Official Guidance Is Based on Symptoms

The CDC updated its guidelines for who should isolate and for how long in October. The guidelines cover:

  • People who have or had COVID-19 and had symptoms;
  • People who tested positive for COVID-19 but did not have symptoms;
  • People who either had severe symptoms of COVID-19 or who have a compromised immune system;
  • People who were exposed to COVID-19, and
  • People who have been reinfected.

Regarding those who are immunocompromised and had COVID-19, the CDC says they “may require testing to determine when they can be around others.”

In addition to noting that people who are immunocompromised may require additional testing, the CDC is also continuously updating its published list of people who are at risk for complications and severe illness if they contract COVID-19. However, as the NIAID study showed, even those with underlying medical conditions can be asymptomatic.

And as the NIAID researchers note, there is more to learn. “Understanding the mechanism of virus persistence and eventual clearance will be essential for providing appropriate treatment and preventing transmission of SARS-CoV-2 because persistent infection and prolonged shedding of infectious SARS-CoV-2 might occur more frequently. Because immunocompromised individuals are often cohorted in hospital settings, a more nuanced approach to testing these individuals is warranted, and the presence of persistently positive people by performing SARS-CoV-2 gRNA and sgRNA analyses on clinical samples should be investigated.”

SARS-CoV-2 Science Is Young

An additional takeaway for pathology lab professionals is the reminder that the scientific research surrounding the novel coronavirus that causes COVID-19 is very young. New insights and understanding will continue to emerge, probably for many years.

One reason why the development of vaccines for COVID-19 has been so quick is that it built on scientific knowledge of the first SARS outbreak and MERS. It’s interesting to note that both SARS and MERS are relatively new as well: SARS emerged in 2002 and MERS in 2012. Compared to a disease like HIV, which was first identified in 1959, scientists have only been working on these particular coronaviruses for a short period of time.

The NIAID study is yet another example of new knowledge and insights emerging about how SARS-CoV-2 infects individuals. Collectively, these findings make it challenging for medical laboratory professionals to stay current with everything relevant and associated with the proper interpretation of COVID-19 test results.

—Dava Stewart

Related Information:

Prolonged Infectious SARS-SoV-2 Shedding from an Asymptomatic Immunocompromised Individual with Cancer

Startling Case Study Finds Asymptomatic COVVID-19 Carrier Who Shed Virus for 70 Days

Shedding of Infectious Virus in Hospitalized Patients with Coronavirus Disease-2019 (COVID-19): Duration and Key Determinants

SARS-CoV-2: The Viral Shedding vs Infectivity Dilemma

Clinical Course and Molecular Viral Shedding Among Asymptomatic and Symptomatic Patients with SARS-CoV-2 Infection in a Community Treatment Center in the Republic of Korea

When You Can Be Around Others

People with Certain Medical Conditions

NAIAD: Coronaviruses

COVID Research Updates: Immune Responses to Coronavirus Persist Beyond Six Months

Medical Laboratories Need to Prepare as Public Health Officials Deal with Latest Coronavirus Outbreak

The CDC has developed a test kit, but deployment to public health laboratories has been delayed by a manufacturing defect

Medical laboratories are on the diagnostic front lines of efforts in the US to contain the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the disease COVID-19, which was first reported in Wuhan City, China. SARS-CoV-2 differs from severe acute respiratory syndrome coronavirus (SARS-CoV), which caused an outbreak of severe acute respiratory syndrome (SARS) in 2003.

Currently, all testing for SARS-CoV-2 in the US is performed by the Centers for Disease Control and Prevention (CDC), using a CDC-developed rapid test known as the 2019-nCoV Real-Time RT-PCR Diagnostic Panel. But soon, testing will be performed by city and state public health (reference) laboratories as well.

At present, medical laboratories are collecting blood specimens for testing by authorized public health labs. However, clinical laboratories should prepare for the likelihood they will be called on to perform the testing using the CDC test or other tests under development.

“We need to be vigilant and understand everything related to the testing and the virus,” said Bodhraj Acharya, PhD, Manager of Chemistry and Referral Testing at the Laboratory Alliance of Central New York, in an exclusive interview with Dark Daily. “If the situation comes that you have to do the testing, you have to be ready for it.”

The CDC has set up a website with information about SARS-CoV-2 (COVID-19) including a section specifically for laboratory professionals. The “Information for Health Departments on Reporting a Person Under Investigation (PUI) or Laboratory-Confirmed Case for COVID-19” section includes guidelines for collecting, handling, and shipping specimens. It also has laboratory biosafety guidelines.

The current criteria for determining PUIs include clinical features, such as fever or signs of lower respiratory illness, combined with epidemiological risks, such as recent travel to China or close contact with a laboratory-confirmed COVID-19 patient. The CDC notes that “criteria are subject to change as additional information becomes available” and advises healthcare providers to consult with state or local health departments if they believe a patient meets the criteria.

Bodhraj Acharya, PhD (above), is Manager of Chemistry and Referral Testing at the Laboratory Alliance of Central New York. In an exclusive interview with Dark Daily, he stressed the importance that medical laboratories be prepared. “We need to be vigilant and be active and understand everything related to this virus and the testing. That’s the role of clinical laboratory scientists, to be ready because this can become a pandemic anytime. It can spread and tomorrow the CDC could announce it is disseminating the test to designated laboratories.” (Photo copyright: Laboratory Alliance of Central New York.)

Test Kit Problems Delay Diagnoses

On Feb. 4, the FDA issued a Novel Coronavirus Emergency Use Authorization (EUA) allowing state and city public health laboratories, as well as Department of Defense (DoD) labs, to perform presumptive qualitative testing using the Real-Time Reverse Transcriptase PCR (RT-PCR) diagnostic panel developed by the CDC. Two days later, the CDC began distributing the test kits, a CDC statement announced. Each kit could test 700 to 800 patients, the CDC said, and could provide results from respiratory specimens in four hours.

However, on Feb. 12, the agency revealed in a telebriefing that manufacturing problems with one of the reagents had caused state laboratories to get “inconclusive laboratory results” when performing the test.

“When the state receives these test kits, their procedure is to do quality control themselves in their own laboratories,” said Nancy Messonnier, MD, Director of the CDC National Center for Immunization and Respiratory Diseases (NCIRD), during the telebriefing. “Again, that is part of the normal procedures, but in doing it, some of the states identified some inconclusive laboratory results. We are working closely with them to correct the issues and as we’ve said all along, speed is important, but equally or more important in this situation is making sure that the laboratory results are correct.”

During a follow-up telebriefing on Feb. 14, Messonnier said that the CDC “is reformulating those reagents, and we are moving quickly to get those back out to our labs at the state and local public health labs.”

Above is a picture of CDC’s laboratory test kit for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). CDC is shipping the test kits to laboratories CDC has designated as qualified, including US state and local public health laboratories, Department of Defense (DOD) laboratories, and select international laboratories. The test kits are bolstering global laboratory capacity for detecting SARS-CoV-2. (Photo and caption copyright: Centers for Disease Control and Prevention.)

Serologic Test Under Development

The current test has to be performed after a patient shows symptoms. The “outer bound” of the virus’ incubation period is 14 days, meaning “we expect someone who is infected to have symptoms some time during those 14 days,” Messonnier said. Testing too early could “produce a negative result,” she continued, because “the virus hasn’t established itself sufficiently in the system to be detected.”

Messonnier added that the agency plans to develop a serologic test that will identify people who were exposed to the virus and developed an immune response without getting sick. This will help determine how widespread it is and whether people are “seroconverting,” she said. To formulate this test, “we need to wait to draw specimens from US patients over a period of time. Once they have all of the appropriate specimens collected, I understand that it’s a matter of several weeks” before the serologic test will be ready, she concluded.

“Based on what we know now, we believe this virus spreads mainly from person to person among close contacts, which is defined [as] about six feet,” Messonnier said at the follow-up telebriefing. Transmission is primarily “through respiratory droplets produced when an infected person coughs or sneezes. People are thought to be the most contagious when they’re most symptomatic. That’s when they’re the sickest.” However, “some spread may happen before people show symptoms,” she said.

The virus can also spread when people touch contaminated surfaces and then touch their eyes, nose, or mouth. But it “does not last long on surfaces,” she said.

Where the Infection Began

SARS-CoV-2 was first identified during an outbreak in Wuhan, China, in December 2019. Soon thereafter, hospitals in the region “were overwhelmed” with cases of pneumonia, Dr. Acharya explained, but authorities could not trace the disease to a known pathogen. “Every time a new pathogen originates, or a current pathogen mutates into a new form, there are no molecular tests available to diagnose it,” he said.

So, genetic laboratories used next-generation sequencing, specifically unbiased nontargeted metagenomic RNA sequencing (UMERS), followed by phylogenetic analysis of nucleic acids derived from the hosts. “This approach does not require a prior knowledge of the expected pathogen,” Dr. Acharya explained. Instead, by understanding the virus’ genetic makeup, pathology laboratories could see how closely it was related to other known pathogens. They were able to identify it as a Betacoronavirus (Beta-CoVs), the family that also includes the viruses that cause SARS and Middle East Respiratory Syndrome (MERS).

This is a fast-moving story and medical laboratory leaders are advised to monitor the CDC website for continuing updates, as well as a website set up by WHO to provide technical guidance for labs.

—Stephen Beale

Related Information:

CDC Tests for COVID-19

CDC: Information for Laboratories

About Coronavirus Disease 2019 (COVID-19)

Real-Time RT-PCR Panel for Detection 2019-Novel Coronavirus

Coronavirus Disease (COVID-19) Outbreak

Coronavirus Disease (COVID-19) Technical Guidance: Laboratory Testing for 2019-nCoV in Humans

Novel Coronavirus Lab Protocols and Responses: Next Steps

WHO: China Leaders Discuss Next Steps in Battle Against Coronavirus Outbreak

Transcript for CDC Telebriefing: CDC Update on Novel Coronavirus February 12

Transcript for CDC Media Telebriefing: Update on COVID-19 February 14

Shipping of CDC 2019 Novel Coronavirus Diagnostic Test Kits Begins

University of Alberta Researchers Develop Surgical Mask That Traps and Kills Infectious Viruses; Protects Hospital Workers and Clinical Laboratory Technicians from Deadly Diseases

As standard masks are used they collect exhaled airborne pathogens that remain living in the masks’ fibers, rendering them infectious when handled

Surgical-style facial masks harbor a secret—viruses that could be infectious to the people wearing them. However, masks can become effective virus killers as well. At least that’s what researchers at the University of Alberta (UAlberta) in Edmonton, Canada, have concluded.

If true, such a re-engineered mask could protect clinical laboratory workers from exposure to infectious diseases, such as, SARS (Severe Acute Respiratory Syndrome), MERS (Middle East Respiratory Syndrome), and Swine Influenza.

“Surgical masks were originally designed to protect the wearer from infectious droplets in clinical settings, but it doesn’t help much to prevent the spread of respiratory diseases such as SARS or MERS or influenza,” Hyo-Jick Choi, PhD, Assistant Professor in UAlberta’s Department of Chemical and Materials Engineering, noted in a press release.

So, Choi developed a mask that effectively traps and kills airborne viruses.

Clinical Laboratory Technicians at Risk from Deadly Infectious Diseases

The global outbreak of SARS in 2003 is a jarring reminder of how infectious diseases impact clinical laboratories, healthcare workers, and patients. To prevent spreading the disease, Canadian-based physicians visited with patients in hotel rooms to keep the virus from reaching their medical offices, medical laboratory couriers were turned away from many doctors’ offices, and hospitals in Toronto ceased elective surgery and non-urgent services, reported The Dark ReportDark Daily’s sister publication. (See The Dark Report, “SARS Challenges Met with New Technology,” April 14, 2003.)

UAlberta materials engineering professor Hyo-Jick Choi, PhD, (right) and graduate student Ilaria Rubino (left) examine filters treated with a salt solution that kills viruses. Choi and his research team have devised a way to improve the filters in surgical masks, so they can trap and kill airborne pathogens. Clinical laboratory workers will especially benefit from this protection. (Photo and caption copyright: University of Alberta.)

How Current Masks Spread Disease

How do current masks spread infectious disease? According to UAlberta researchers:

  • A cough or a sneeze transmits airborne pathogens such as influenza in aerosolized droplets;
  • Virus-laden droplets can be trapped by the mask;
  • The virus remains infectious and trapped in the mask; and,
  • Risk of spreading the infection persists as the mask is worn and handled.

“Aerosolized pathogens are a leading cause of respiratory infection and transmission. Currently used protective measures pose potential risk of primary and secondary infection and transmission,” the researchers noted in their paper, published in Scientific Reports.

That’s because today’s loose-fitting masks were designed primarily to protect healthcare workers against large respiratory particles and droplets. They were not designed to protect against infectious aerosolized particles, according to the Centers for Disease Control and Prevention (CDC).

In fact, the CDC informed the public that masks they wore during 2009’s H1N1 influenza virus outbreak provided no assurance of infection protection.

“Face masks help stop droplets from being spread by the person wearing them. They also keep splashes or sprays from reaching the mouth and nose of the person wearing the face mask. They are not designed to protect against breathing in very small particle aerosols that may contain viruses,” a CDC statement noted.

Pass the Salt: A New Mask to Kill Viruses

Choi and his team took on the challenge of transforming the filters found on many common protective masks. They applied a coating of salt that, upon exposure to virus aerosols, recrystallizes and destroys pathogens, Engineering360 reported.

“Here we report the development of a universal, reusable virus deactivation system by functionalization of the main fibrous filtration unit of surgical mask with sodium chloride salt,” the researchers penned in Scientific Reports.

The researchers exposed their altered mask to the influenza virus. It proved effective at higher filtration compared to conventional masks, explained Contagion Live. In addition, viruses that came into contact with the salt-coated fibers had more rapid infectivity loss than untreated masks.

How Does it Work?

Here’s how the masks work, according to the researchers:

  • Aerosol droplets carrying the influenza virus contact the treated filter;
  • The droplet absorbs salt on the filter;
  • The virus is exposed to increasing concentration of salt; and,
  • The virus is damaged when salt crystallizes.

“Salt-coated filters proved highly effective in deactivating influenza viruses regardless of [influenza] subtypes,” the researchers wrote in Scientific Reports. “We believe that [a] salt-recrystallization-based virus deactivation system can contribute to global health by providing a more reliable means of preventing transmission and infection of pandemic or epidemic diseases and bioterrorism.”

Other Reports on Dangerous Exposure for Clinical Laboratory Workers

This is not the first time Dark Daily has reported on dangers to clinical laboratory technicians and ways to keep them safe.

In “Health of Pathology Laboratory Technicians at Risk from Common Solvents like Xylene and Toluene,” we reported on a 2011 study that determined medical laboratory technicians who handle common solvents were at greater risk of developing auto-immune connective tissue diseases.

And more recently, in “Europe Implements New Anatomic Pathology Guidelines to Reduce Nurse Exposure to Formaldehyde and Other Toxic Histology Chemicals,” we shared information on new approaches to protect nurses from contacting toxic chemicals, such as formalin, toluene, and xylene.

The UAlberta team may have come up with an inexpensive, simple, and effective way to protect healthcare workers and clinical laboratory technicians. Phlebotomists, laboratory couriers, and medical technologists also could wear the masks as protection from accidental infection and contact with specimens. It will be interesting to follow the progress of this special mask with its salty filter.

—Donna Marie Pocius

Related Information:

Researcher Turns “SARS Mask” into a Virus Killer

Universal Reusable Virus Deactivation System for Respiratory Protection

Understanding Respiratory Protection Options in Healthcare

H1N1 Flu and Masks

Arming Surgical Masks to Kill Viruses

New Surgical Mask Designed to Kill Viruses

SARS Challenges Met with New Technology

Toronto Hospital Labs Cope with SARS Impact

Europe Implements New Anatomic Pathology Guidelines to Reduce Nurse Exposure to Formaldehyde and Other Toxic Histology Chemicals

Health of Laboratory Technicians at Risk from Common Solvents Like Xylene and Toluene