New biomarker may lead to new clinical laboratory testing and treatments for long COVID
Researchers studying long COVID at the University Hospital of Zurich (UZH) and the Swiss Institute of Bioinformatics (SIB), both in Switzerland, have discovered a protein biomarker in blood that indicates a component of the body’s innate immune system—called the complement system—remains active in some individuals long after the infection has run its course. The scientists are hopeful that further studies may provide clinical laboratories with a definitive test for long COVID, and pharma companies with a path to develop therapeutic drugs to treat it.
Ever since the COVID-19 pandemic began, a subset of the population worldwide continues to experience lingering symptoms even after the acute phase of the illness has passed. Patients with long COVID experience symptoms for weeks, even months after the initial viral infection has subsided. And because these symptoms can resemble other illnesses, long COVID is difficult to diagnose.
This new biomarker may lead to new clinical laboratory diagnostic blood tests for long COVID, and to a greater understanding of why long COVID affects some patients and not others.
“Those long COVID patients used to be like you and me, totally integrated [into] society with a job, social life, and private life,” infectious disease specialist Michelè van Vugt, MD (above), Senior Fellow and Professor at Amsterdam Institute for Global Health and Development (AIGHD), told Medical News Today. “After their COVID infection, for some of them, nothing was left because of their extreme fatigue. And this happened not only in one patient but many more—too many for only [a] psychological cause.” Clinical laboratories continue to perform tests on patients experiencing symptoms of COVID-19 even after the acute illness has passed. (Photo copyright: AIGHD.)
Role of the Complement System
To complete their study, the Swiss scientists monitored 113 patients who were confirmed through a reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) test to have COVID-19. The study also included 39 healthy control patients who were not infected.
The researchers examined 6,596 proteins in 268 blood samples collected when the sick patients were at an acute stage of the virus, and then again six months after the infection. They found that 40 of the patients who were sick with COVID-19 eventually developed symptoms of long COVID. Those 40 patients all had a group of proteins in their blood showing that the complement system of their immune system was still elevated even after recovering from the virus.
“Complement is an arm of the immune system that ‘complements’ the action of the other arms,” Amesh Adalja, MD, Adjunct Assistant Professor at Johns Hopkins Bloomberg School of Public Health, told Prevention, “Activities that it performs range from literally attacking the cell membranes of a pathogen to summoning the cells of other immune systems to the site of infection.”
In addition to helping bodies heal from injury and illness, the complement immune system also activates inflammation in the body—and if the complement system is activated for too long the patient is at risk for autoimmune disease and other inflammatory conditions.
Conducted by genetic scientists at Trinity College Dublin and St. James’ Hospital in Dublin, Ireland, the study “analyzed blood samples—specifically, serum and plasma—from 76 patients who were hospitalized with COVID-19 in March or April 2020, along with those from 25 people taken before the pandemic. The researchers discovered that people who said they had brain fog had higher levels of a protein in their blood called S100β [a calcium-binding protein] than people who didn’t have brain fog,” Prevention reported.
“S100β is made by cells in the brain and isn’t normally found in the blood. That suggests that the patients had a breakdown in the blood-brain barrier, which blocks certain substances from getting to the brain and spinal cord, the researchers noted,” Prevention reported.
“The scientists then did MRI scans with dye of 22 people with long COVID (11 of them who reported having brain fog), along with 10 people who recovered from COVID-19. They found that long COVID patients who had brain fog had signs of a leaky blood-brain barrier,” Prevention noted.
“This leakiness likely disrupts the integrity of neurons in the brain by shifting the delicate balance of materials moving into and out of the brain,” Matthew Campbell, PhD, Professor and Head of Genetics at Trinity College Dublin, told Prevention.
Interactions with Other Viruses
According to Medical News Today, the Swiss study results also suggest that long COVID symptoms could appear because of the reactivation of a previous herpesvirus infection. The patients in the study showed increased antibodies against cytomegalovirus, a virus that half of all Americans have contracted by age 40.
The link between long COVID and these other viruses could be key to developing treatment for those suffering with both illnesses. The antiviral treatments used for the herpesvirus could potentially help treat long COVID symptoms as well, according to Medical News Today.
“Millions of people across the planet have long COVID or will develop it,” Thomas Russo MD, Professor and Chief of Infectious Disease at the University at Buffalo in New York, told Prevention. “It’s going to be the next major phase of this pandemic. If we don’t learn to diagnose and manage this, we are going to have many people with complications that impact their lives for the long term.”
Long COVID won’t be going away any time soon, much like the COVID-19 coronavirus. But these two studies may lead to more effective clinical laboratory testing, diagnoses, and treatments for millions of people suffering from the debilitating condition.
Data was used to create a transmission map that tracked the spread of infections among school athletes and helped public health officials determine where best to disrupt exposure
Genomic sequencing played a major role in tracking a SARS-CoV-2 outbreak in a Minnesota school system. Understanding how and where the coronavirus was spreading helped local officials implement restrictions to help keep the public safe. This episode demonstrates how clinical laboratories that can quickly sequence SARS-CoV-2 accurately and at a reasonable cost will give public health officials new tools to manage the COVID-19 pandemic.
Officials in Carver County, Minn., used the power of genomic epidemiology to map the COVID-19 outbreak, and, according to the Star Tribune, revealed how the B.1.1.7 variant of the SARS-CoV-2 coronavirus was spreading through their community.
“The resulting investigation of the Carver County outbreak produced one of the most detailed maps of COVID-19 transmission in the yearlong history of the pandemic—a chart that looks like a fireworks grand finale with infections producing cascading clusters of more infections,” the Star Tribune reported.
Using genetic sequencing, the Minnesota Department of Health produced the above map of the spread of the COVID-19 through Carver County’s schools. The animated graph includes epidemiological data from “10 high school teams, 10 club teams, 12 teams in a sports association, and three fitness/rec centers.” According to the Star Tribune, “The cluster shows a high ‘attack rate’ of infected people spreading the virus to multiple close contacts. Genomic sequencing found the more infectious B.1.1.7 variant of the virus in about a quarter of cases so far.” Click here to access the interactive version of the map. To see details about specific persons and locations, tap or hover over each dot. (Graphic copyright: Minnesota Department of Health/Star Tribune.)
Private Labs, Academic Labs, Public Health Labs Must Work Together
For gene sequencing to guide policy and decision making as well as it did in Carver County, coordination, cooperation, and standardization among public, private, and academic medical laboratories is required. Additionally, each institution must report the same information in similar formats for it to be the most useful.
“Maintain Policies That Slow Transmission: Variants will continue to emerge as the pandemic unfolds, but the best chance of minimizing their frequency and impact will be to continue public health measures that reduce transmission. This includes mask mandates, social distancing requirements, and limited gatherings.
“Prioritize Contact Tracing and Case Investigation for Data Collection: Cases of variants of concern should be prioritized for contact tracing and case investigation so that public health officials can observe how the new variant behaves compared to previously circulating versions.
“Develop a Genomic Surveillance Strategy: To guide the public health response, maximize resources, and ensure an equitable distribution of benefits, the US Department of Health and Human Services (HHS) should develop a national strategy for genomic surveillance to implement and direct a robust SARS-CoV-2 genomic surveillance program, drawing on resources and expertise from across the US government.
“Improve Coordination for Genomic Surveillance and Characterization: There are several factors in creating a successful genomic surveillance and characterization network. Clear leadership and coordination will be necessary.”
Practical Application of Genomic Sequencing
Genomic epidemiology uses the genetic sequence of a virus to better understand how and where a given virus is spreading, as well as how it may be mutating. Pathologists understand that this information can be used at multiple levels.
Locally, as was the case in Carver County, Minn., it helps school officials decide whether to halt sports for a time. Nationally, it helps scientists identify “hot spots” and locate mutations of the coronavirus. Using this data, vaccine manufacturers can adjust their vaccines or create boosters as needed.
“This is some of the most amazing epidemiology I’ve ever seen,” epidemiologist Michael Osterholm, PhD, Regents Professor, and Director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, told the Star Tribune, which reported that “A public health investigation linked 140 COVID-19 cases among more than 50 locations and groups, mostly schools and sports teams in Carver County. (Photo copyright: University of Minnesota.)
Will Cost Decreases Provide Opportunities for Clinical Laboratories?
Every year since genomic sequencing became available the cost has decreased. Experts expect that trend to continue. However, as of now, the cost may still be a barrier to clinical laboratories that lack financial resources.
“Purchasing laboratory equipment, computer resources, and staff training requires significant up-front investments. However, the cost per sequence is far less today than it was under earlier methods,” the GAO noted. This is good news for public and independent clinical laboratories. Like Carver County, a significant SARS-CoV-2 outbreak in the future may be averted thanks to genetic sequencing.
“The first piece of the cluster was spotted in a private K-8 school, which served as an incubator of sorts because its students live in different towns and play on different club teams,” the Star Tribune reported.
Finding such clusters may provide opportunities to halt the outbreak. “We can try to cut it off at the knees or maybe get ahead of it,” epidemiologist Susan Klammer with Minnesota Public Health and for childcare and schools, told the Star Tribune.
This story is a good example of how genomic sequencing and surveillance tracking—along with cooperation between public health agencies and clinical laboratories—are critical elements in slowing and eventually halting the spread of COVID-19.
Clinical laboratories may see increase in flu and COVID-19 specimen processing as people return to pre-pandemic social behaviors, experts predict
While SARS-CoV-2 infections continue to ravage many parts of the world, influenza (flu) cases in North America have hit a historic low. As winter approached last year, infectious disease experts warned of a “twindemic” in which the COVID-19 outbreak would combine with seasonal influenza to overwhelm the healthcare system. But this did not happen, and many doctors and medical laboratory scientists are now investigating this unexpected, but welcomed, side-effect of the pandemic.
From the start of the current flu season in September 2020, clinical laboratories in the US reported that 1,766 specimens tested positive for flu out of 931,726—just 0.2%—according to the CDC’s Weekly US Influenza Surveillance Report. That compares with about 250,000 positive specimens out of 1.5 million tested in the 2019-2020 flu season, the CDC reported. Public health laboratories reported 243 positive specimens out of 438,098 tested.
The graphic above taken from the CDC’s Weekly Influenza Surveillance Report for the week ending April 17, 2021, illustrates how “Nationwide during week 15, 1.1% of patient visits reported through ILINet were due to ILI [Influenza-like Illness].” This percentage, according to the CDC, is below the national baseline of 2.6%. “Seasonal influenza activity in the United States remains lower than usual for this time of year.” (Graphic copyright: Federal Centers for Disease Control and Prevention.)
Fear of COVID-19 Linked to Fewer Flu Deaths in Children
WebMD reported that just one child in the US has died from the flu this year, compared with 195 in 2020. Why the low numbers?
Precautions people take to avoid COVID-19 transmission, including masking, social distancing, and handwashing.
Reduced human mobility, including less international travel.
Higher-than-usual flu vaccination rates. As of February 26, the CDC reported that nearly 194 million doses of flu vaccine had been distributed in the US.
WebMD noted this could be a record, but that the CDC data doesn’t indicate how many doses were actually administered.
However, Schaffner told WebMD that efforts to keep kids home from school and away from social gatherings were likely a bigger factor. “Children are the great distributors of the influenza virus in our society,” he said. But due to fears about COVID-19 transmission, kids “weren’t even playing together, because mothers were keeping them off the playground and not having play dates.”
Repercussions for Fighting Flu Next Year
Public health experts welcomed the low flu levels, however, Politico reported that limited data about flu circulation this year could hamper efforts to develop an effective vaccine for next season’s flu strains.
Each February, Politico explained, experts convened by the World Health Organization (WHO) look at data from the current and previous flu seasons to predict which strains are likely to predominate in the Northern Hemisphere next winter. That includes data about which strains are currently circulating in the Southern Hemisphere. The WHO uses these predictions to recommend the composition of flu vaccines. In the US, the final decision is made by an FDA advisory committee.
A similar WHO meeting in September guides vaccine development in the Southern Hemisphere.
The WHO issued this year’s Northern Hemisphere recommendations on Feb. 26. The advisory includes recommendations for egg-based and cell- or recombinant-based vaccines, and for quadrivalent (four-strain) or trivalent (three-strain) vaccines.
In a document accompanying the recommendations, the WHO acknowledged concerns about this year’s limited pool of data.
“The volume of data available from recently circulating influenza viruses, and the geographic representation, have been significantly lower for this northern hemisphere vaccine recommendation meeting than is typical,” the document stated. “The reduced number of viruses available for characterization raises uncertainties regarding the full extent of the genetic and antigenic diversity of circulating influenza viruses and those likely to pose a threat in forthcoming seasons.”
The report notes that experts identified changes in circulating Influenza A(H3N2) viruses this year, and that the changes are reflected in the new vaccine recommendation.
But Paul A. Offit, MD, who serves on the FDA’s vaccine advisory panel, downplayed worries about the vaccine. “The belief is that there was enough circulating virus to be able to pick what is likely to be the strains that are associated with next year’s flu outbreak,” he told Politico. Offit is a Professor of Vaccinology and Pediatrics at the Perelman School of Medicine at the University of Pennsylvania and Director of the Vaccine Education Center at the Children’s Hospital of Philadelphia.
Pediatrician and internationally recognized expert in the fields of virology and immunology, Paul A. Offit, MD (above), told Politico that the low level of flu circulation this year, along with the resulting uncertainty, “is unprecedented.” Clinical laboratories might not have noticed the severe decrease in influenza specimens sent for processing due to being hyper-focused on COVID-19 testing. But as the pandemic subsides, loss of flu testing revenues will likely become more apparent. (Photo copyright: University of Pennsylvania.)
Offit suggests that efforts to mitigate the COVID-19 outbreak could be useful to combat other infectious disease outbreaks. However, both Offit and Gostin expressed doubt about that prospect.
“I mean, could we reasonably in a winter month, wear masks just at least when we’re outside in large crowds? … Or are we comfortable having hundreds of 1000s of cases of hospitalizations for flu and 10s of 1000s [of] deaths? I suspect the answer is B. We’re comfortable with that, we’re willing to have that even though we just learned, there’s a way to prevent it,” Offit told Politico.
“Remember after the 1918 flu pandemic, most people don’t realize what happened when that was over. But what happened was the roaring ‘20s,” Gostin told Politico. “People started congregating, mingling, hugging, kissing. All the things they missed. They crowded into theaters and stadiums and went back to church. That’s what’s likely to happen this fall and that makes the influenza virus very happy.”
So, what should clinical laboratories expect in future flu and COVID-19 vaccines? That is not yet clear. One thing is certain, though. New lab test panels that test for influenza and the SARS-CoV-2 coronavirus will be arriving in the marketplace.
Might clinical laboratories soon be called on to conduct mass testing to find people who show little or no symptoms even though they are infected with the coronavirus?
Clinical laboratory managers understand that as demand for COVID-19 testing exceeds supplies, what testing is done is generally performed on symptomatic patients. And yet, it is the asymptomatic individuals—those who are shown to be infected with the SARS-CoV-2 coronavirus, but who experience no symptoms of the illness—who may hold the key to creating effective treatments and vaccinations.
So, as the COVID-19 pandemic persists, scientists are asking why some people who are infected remain asymptomatic, while others die. Why do some patients get severely ill and others do not? Researchers at the University of California San Francisco (UCSF) and Stanford University School of Medicine (Stanford Medicine) are attempting to answer these questions as they investigate viral transmission, masking, immunity, and more.
And pressure is increasing on researchers to find the answer. According to Monica Gandhi, MD, MPH, an infectious disease specialist and Professor of Medicine at UCSF, millions of people may be asymptomatic and unknowingly spreading the virus. Gandhi is also Associate Division Chief (Clinical Operations/Education) of the Division of HIV, Infectious Diseases, and Global Medicine at UCSF’s Zuckerberg San Francisco General Hospital and Trauma Center.
“If we did a mass testing campaign on 300 million Americans right now, I think the rate of asymptomatic infection would be somewhere between 50% and 80% of cases,” she told UCSF Magazine.
On a smaller scale, her statement was borne out. In a study conducted in San Francisco’s Mission District during the first six weeks of the city’s shelter-in-place order, UCSF researchers conducted SARS-CoV-2 reverse transcription-PCR and antibody (Abbott ARCHITECT IgG) testing on 3,000 people. Approximately 53% tested positive for COVID-19 but had no symptoms such as fever, cough, and muscle aches, according to data reported by Carina Marquez, MD, UCSF Assistant Professor of Medicine and co-author of the study, in The Mercury News.
Pandemic Control’s Biggest Challenge: Asymptomatic People
In an editorial in the New England Journal of Medicine (NEJM), Gandhi wrote that transmission of the virus by asymptomatic people is the “Achilles heel of COVID-19 pandemic control.”
In her article, Gandhi compared SARS-CoV-2, the coronavirus that causes COVID-19, to SARS-CoV-1, the coronavirus that caused the 2003 SARS epidemic. One difference lies in how the virus sheds. In the case of SARS-CoV-2, that takes place in the upper respiratory tract, but with SARS-CoV-1, it takes place in the lower tract. In the latter, symptoms are more likely to be detected, Gandhi explained. Thus, asymptomatic carriers of the coronavirus may go undetected.
“Viral loads with SARS-CoV-1, which are associated with symptom onset, peak a median of five days later than viral loads with SARS-CoV-2, which makes symptom-based detection of infection more effective in the case of SARS-CoV-1,” Gandhi wrote. “With influenza, persons with asymptomatic disease generally have lower quantitative viral loads in secretions from the upper respiratory tract than from the lower respiratory tract and a shorter duration of viral shedding than persons with symptoms, which decreases the risk of transmission from paucisymptomatic persons.”
Rick Wright (above), an insurance broker in Redwood City, Calif., was infected with the COVID-19 coronavirus while aboard a Diamond Princess Cruise. He underwent 40 days of isolation, and though he consistently tested positive for the coronavirus, he experienced no symptoms of the illness. “I never felt sick. Not a cough, wheezing, headache. Absolutely nothing,” he told Mercury News. (Photo copyright: The Mercury News.)
Stanford Studies Immune Responses in COVID-19 Patients
Meanwhile, scientists at the Stanford University School of Medicine were on their own quest to find out why COVID-19 causes severe disease in some people and mild symptoms in others.
“One of the great mysteries of COVID-19 infections has been that some people develop severe disease, while others seem to recover quickly. Now, we have some insight into why that happens,” Bali Pulendran, PhD, Stanford Professor of Pathology, Microbiology, and Immunology and Senior Author of the study in a Stanford Medicine news release.
The Stanford research suggested that three molecules—EN-RAGE, TNFSF14, and oncostatin-M—“correlated with disease and increased bacterial products in human plasma” of COVID-19 patients.
“Our multiplex analysis of plasma cytokines revealed enhanced levels of several proinflammatory cytokines and a strong association of the inflammatory mediators EN-RAGE, TNFSF14, and OSM with clinical severity of the disease,” the scientists wrote in Science.
Pulendran hypothesized that the molecules originated in patients’ lungs, which was the infection site.
“These findings reveal how the immune system goes awry during coronavirus infections, leading to severe disease and point to potential therapeutic targets,” Pulendran said in the news release, adding, “These three molecules and their receptors could represent attractive therapeutic targets in combating COVID-19.”
Clinical Laboratories May Do More Testing of Asymptomatic People
The research continues. In a televised news conference, President Trump said COVID-19 testing plays an important role in “preventing transmission of the virus.” Clearly this is true and learning why some people who are infected experience little or no symptoms may be key to defeating COVID-19.
Thus, as the nation reopens, clinical laboratories may want to find ways to offer COVID-19 testing beyond hospitalized symptomatic patients and people who show up at independent labs with doctors’ orders. As supplies permit, laboratory managers may want to partner with providers in their communities to identify people who are asymptomatic and appear to be well, but who may be transmitting the coronavirus.
It can take up to eight days after onset of symptoms for a person’s immune system to develop antibodies, so serological tests are not designed for diagnosing recent or active infections, stated a Mayo Clinic news story. However, Reuters reported that the availability of serological tests is “a potential game changer” because they could identify people who are immune even if they had no symptoms or only mild symptoms.
“Ultimately, this might help us figure out who can get the country back to normal,” Florian Krammer, PhD, told Reuters. Krammer’s lab at the Icahn School of Medicine at Mount Sinai in New York City has developed a serological test. “People who are immune could be the first people to go back to normal life and start everything up again,” he said.
However, some experts advise that the presence of antibodies is not necessarily a “get out of jail free” card when it comes to the coronavirus. “Infectious disease experts say immunity against COVID-19 may last for several months and perhaps a year or more based on their studies of other coronaviruses, including Severe Acute Respiratory Syndrome (SARS), which emerged in 2003,” reported Reuters. “But [the experts] caution that there is no way to know precisely how long immunity would last with COVID-19, and it may vary person to person.”
Additionally, it is also “uncertain whether antibodies would be sufficient protection if a person were to be re-exposed to the virus in very large amounts,” such as in an emergency room or ICU, Reuters reported.
Serological Survey Studies Get Underway Worldwide
Aside from detecting potential immunity, the World Health Organization (WHO) says serological tests could be useful for widespread disease surveillance and epidemiological research.
In the US, the Vitalant
Research Institute is leading several large serological survey or
“serosurvey” studies in which regional blood centers save samples of donated
blood for antibody testing, Science
reported.
Science also reported on a similar WHO initiative in which six countries will pool data from their own antibody studies. And in the Netherlands, blood banks have begun screening thousands of blood donations for presence of antibodies, Wired reported.
FDA Emergency Use Authorization
On March 16, the federal Food and Drug Administration (FDA) announced that it would allow commercial development and distribution of serological tests that “identify antibodies (e.g., IgM, IgG) to SARS-CoV-2 from clinical specimens” without an Emergency Use Authorization (EUA). The agency noted that these tests are “less complex than molecular tests” used to detect active infections, and that the policy change is limited to such testing in medical laboratories or by healthcare workers at the point-of-care. “This policy does not apply to at home testing,” the FDA reiterated.
“Serological tests can play a critical role in the fight against COVID-19 by helping healthcare professionals to identify individuals who have overcome an infection in the past and have developed an immune response,” said FDA Commissioner Stephen M. Hahn, MD (above with President Trump during a Coronavirus Task Force press briefing), in an April 7 press statement. “In the future, this may potentially be used to help determine—together with other clinical data—that such individuals are no longer susceptible to infection and can return to work. In addition, these test results can aid in determining who may donate a part of their blood called convalescent plasma, which may serve as a possible treatment for those who are seriously ill from COVID-19.” (Photo copyright: CNBC.)
FDA Issues First EUA for Rapid Diagnostic Test
Cellex Inc., based in Research Triangle Park, N.C., received the first EUA for its qSARS-CoV-2 serological test on April 1. As with other rapid diagnostic tests (RDTs) under development, the qSARS-CoV-2 test detects the presence of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies in human blood. The biotechnology company’s RDT can be used to test serum, plasma, or whole-blood specimens, stated Cellex, and can produce results in 15 to 20 minutes.
The FDA has authorized use of the antibody test only by laboratories certified under CLIA to perform moderate and high complexity tests. Cellex has set up a COVID-19 website with information about the qSARS-CoV-2 test for clinical laboratories, patients, and healthcare providers.
Other Serological Tests Under Development
Mayo
Clinic Laboratories announced on April 13 that it is ramping up
availability of an internally-developed serological test. “Initial capacity
will be 8,000 tests per day performed at laboratory locations across Mayo Clinic,” stated the announcement.
“Testing will be performed 24 hours a day, and Mayo Clinic Laboratories is working
to ensure turnaround time is as close as possible to 24 hours after receipt of
the sample.”
Emory University in Atlanta announced on April 13 that it will begin deploying its own internally developed antibody test. Initially, testing will be limited to 300 people per day, comprised of Emory Healthcare patients, providers, and staff members. Eventually, testing will be “expanded significantly,” said Emory, with a goal of 5,000 tests per day by mid-June.
RDTs are typically qualitative, meaning they produce a
positive or negative result, stated the Center for Health Security. An ELISA
test “can be qualitative or quantitative,” noted the Center, but it can take
one to five hours to produce results.
A third type of serological test—the neutralization assay—involves infecting a patient’s blood with live coronavirus to determine if antibodies exist that can inhibit growth of the virus. The test takes three to five days in a level 3 biosafety laboratory to produce results. The Straits Times reported on one laboratory in Singapore that developed a neutralization assay to trace the source of COVID-19 infections that originated in Wuhan, China.
Serological testing is another important tool clinical
laboratories and epidemiologists can use to fight and ultimately defeat the
COVID-19 pandemic and is worth watching.
