Study of the 50 Omicron variants could lead to new approaches to clinical laboratory testing and medical treatments for long COVID
Patients infected with SARS-CoV-2 can usually expect the COVID-19 illness to subside within a couple of weeks. However, one Dutch patient remained infected with the coronavirus for 612 days and fought more than 50 mutations (aka, variants) before dying late last year of complications due to pre-existing conditions. This extreme case has given doctors, virologists, microbiologists, and clinical laboratories new insights into how the SARS-CoV-2 virus mutates and may lead to new treatments for long COVID.
The medication the patient was taking for his pre-existing conditions may have contributed to his body being unable to produce antibodies in response to three shots of the Moderna mRNA COVID vaccine he received.
Magda Vergouwe, MD, PhD candidate at the Center for Experimental and Molecular Medicine (CEMM), Amsterdam UMC, who lead a study into the patient, theorized that some of the medications the patient was on for his pre-existing conditions could have destroyed healthy cells alongside the abnormal cancer-causing B cells the drugs were meant to target.
“This case underscores the risk of persistent SARS-CoV-2 infections in immunocompromised individuals,” the researchers said prior to presenting their report about the case at a meeting of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) in Barcelona, Spain, Time reported. “We emphasize the importance of continuing genomic surveillance of SARS-CoV-2 evolution in immunocompromised individuals with persistent infections.”
“Chronic infections and viral evolution [are] commonly described in [the] literature, and there are other cases of immunocompromised patients who have had [COVID] infections for hundreds of days,” Magda Vergouwe, MD, PhD candidate (above), Center for Experimental and Molecular Medicine at Amsterdam UMC, told Scientific American. “But this is unique due to the extreme length of the infection … and with the virus staying in his body for so long, it was possible for mutations to just develop and develop and develop.” Microbiologists, virologists, and clinical laboratories involved in testing patients with long COVID may want to follow this story. (Photo copyright: LinkedIn.)
Risks to Immunocompromised Patients
Pre-existing conditions increase the risk factor for COVID-19 infections. A 2021 study published in the Journal of the American Board of Family Medicine (JABFM) titled, “Prevalence of Pre-existing Conditions among Community Health Center Patients with COVID-19,” found that about 61% of that study’s test group had a pre-existing condition prior to the outbreak of the COVID-19 pandemic.
When the Dutch man was admitted to Amsterdam UMC with common and serious COVID-19 symptoms, such as shortness of breath, a cough, and low blood oxygen levels, he was prescribed sotrovimab (a monoclonal antibody) along with other COVID treatments.
About a month after being admitted his COVID-19 symptoms decreased, so he was first discharged to a rehab facility and then finally to his home. However, he continued to test positive for the coronavirus and developed other infections that may have been complicated by the persistent case of COVID-19.
The Amsterdam UMC doctors emphasized that the man ultimately succumbed to his pre-existing conditions and not necessarily COVID-19.
“It’s important to note that in the end he did not die from his COVID-19,” Vergouwe told Scientific American. “But he did keep it with him for a very long period of time until then, and this is why we made sure to sample [the virus in his body] as much as we could.”
One in Five Adults Develop Long COVID
Long COVID does not necessarily indicate an active infection. However, in as many as one in five US adults COVID symptoms persist after the acute phase of the infection is over, according to a study published recently in JAMA Network Open titled, “Epidemiologic Features of Recovery from SARS-CoV-2 Infection.”
“In this cohort study, more than one in five adults did not recover within three months of SARS-CoV-2 infection. Recovery within three months was less likely in women and those with pre-existing cardiovascular disease and more likely in those with COVID-19 vaccination or infection during the Omicron variant wave,” the JAMA authors wrote.
The origins of long COVID are not entirely clear, but according to the National Institutes of Health (NIH) it can develop when a patient is unable to sufficiently rest while battling off the initial virus. According to Vergouwe, the SARS-CoV-2 genome will always grow quicker when found in a patient with a compromised immune system.
Unique COVID-19 Mutations
More than 50 new mutations of the original Omicron variant were identified in the Dutch patient. According to Vergouwe, “while that number can sound shocking, mutations to the SARS-CoV-2 genome are expected to evolve more quickly in those who are immunocompromised (the average mutation rate of the virus is estimated to be two mutations per person per month),” Scientific American reported. “What does make these mutations unusual, she noted, is how their features differed vastly from mutations observed in other people with COVID. [Vergouwe] hypothesizes that the exceptional length of the individual’s infection, and his pre-existing conditions, allowed the virus to evolve extensively and uniquely.”
COVID-19 appears to be here to stay, and most clinical laboratory managers and pathologists understand why. As physicians continue to learn about the SARS-CoV-2 coronavirus, this is another example of how the knowledge about SARS-CoV-2 is growing as different individuals are infected with different variants of the virus.
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.
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.
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.
