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.
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.
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.
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.
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 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.
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.”
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.
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 Report—Dark 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.
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.