(CN) — One of the world’s leading virologists suspects there is a growing mass of undetected, symptomless cases of the new coronavirus strain due to technical limitations on diagnostic test kits.
Dr. Christian Brechot, president of the Global Virus Network and professor at the University of South Florida, said in an interview that tracking the spread of the coronavirus has been hampered because current diagnostic kits cannot reliably detect cases of the virus in people who recovered from their infection or experienced no symptoms.
The virus, dubbed COVID-19, has been wreaking havoc across the globe, with major outbreaks in China, South Korea, Italy and Iran. The first major documented outbreak was in the Hubei province of China, where approximately 3,000 deaths have been linked to the pathogen. The Chinese government in late January locked down millions of residents in the city of Wuhan and surrounding areas, a quarantine that was unprecedented in scale in modern history.
In the U.S., there have been 10 deaths linked to the virus in Washington state, several of which stemmed from an outbreak at a nursing home in a Seattle suburb. California on Wednesday reported its first death from the virus.
The available diagnostic kits in the U.S. and abroad aim to detect viral RNA molecules in patients’ saliva and nasal swabs. The kits are effective at diagnosing active infections, Brechot said. What we don’t have yet are serology-based kits that can detect the immune system’s antibodies to the virus, a test method that would help identify people who have been exposed to the virus but did not develop severe infection.
“You have these other tests, which are the serology-based assays. Why do none of the countries have this test, which would allow not only testing of how many patients are infected, but also how many have been exposed to virus?” Brechot asked.
The physician and researcher explained that the challenge in developing this second type of test lies in making sure the results do not conflate the new, more deadly coronavirus strain with common coronavirus strains.
“The problem is that each year, we have several coronaviruses that are infecting humans. We just call those the common cold. When you want to detect this new strain, you have cross-reactivity with the other viruses,” Brechot noted. “You don’t know whether you are detecting COVID-19 or remnant signals of exposure to mundane viruses.”
Researchers ran into the same challenge when trying to develop serology-based diagnostics for SARS-1 coronavirus, which generated a 2002-2003 China epidemic that killed more than 700 people.
If the serology-based tests were available, Brechot said, we might be “surprised to find how many individuals” have been exposed to the new COVID-19 strain but “are absolutely healthy and recovered without symptoms.”
According to Todd Ellerin, a Harvard professor and infectious disease specialist in Weymouth, a person who is not showing symptoms of COVID-19 “may be shedding the virus and could make others ill.” Ellerin wrote in a post on Harvard’s web site: “How often asymptomatic transmission is occurring is unclear.”
Preliminary research released last month by China’s disease control agency indicated the virus caused only mild symptoms in 80% of the 44,000 Chinese cases analyzed. The overall fatality rate was 20 times higher than the flu, however. In the patient group studied between the ages of 60 to 69, the virus killed roughly one in 28 people.
Before realizing community spread of COVID-19 was underway in the U.S., health officials in many states were focusing on patients’ travel history in deciding whether to screen them for the virus.
The Florida Department of Health, for instance, was doing limited screening, primarily on patients who had traveled to areas of the world with active outbreaks. That was until last week, when the department expanded criteria for COVID-19 testing to include nearly any patient who had unexplained respiratory illness.
The Centers for Disease Control and Prevention for its part widened its guidelines on March 4 for when to test patients.
“Clinicians should use their judgment to determine if a patient has signs and symptoms compatible with COVID-19 and whether the patient should be tested. Decisions on which patients receive testing should be based on the local epidemiology of COVID-19,” the updated CDC guidance reads.
Brechot pointed out that the CDC and partnering federal agencies have improved diagnostic infrastructure, allowing state health labs nationwide to perform quick screening of patient saliva samples before sending the samples to the CDC for confirmation of results.
When asked if labs in the U.S. should have started blanket testing on patients with unexplained respiratory illness earlier, the doctor said: “Likely yes, but they were unable to do it.”
“This is not specific to the U.S. The same has happened in France and Italy. It’s a new virus, so they were unable to use existing diagnostic kits,” Brechot said.
As far as developing a vaccine, Brechot said the timeline is unpredictable but that researchers hope to have one ready for mass distribution by early next year.
In the meanwhile, virologists are scrambling to find a treatment.
“We don’t have a drug that will specifically target the virus. Strangely enough, we did not have it either on the first SARS [coronavirus]. We did not have it on the Middle East Respiratory Syndrome virus. This means something: it means that it is not easy to develop,” Brechot explained.
Drug companies are looking into whether medications for other viruses could help patients with COVID-19. According to a report in Genetic Engineering & Biotechnology News, Chinese studies are underway to evaluate whether COVID-19 can be effectively treated with remdesivir, an anti-viral drug previously researched as an Ebola treatment.
Among other compounds, the anti-malarial chloroquine phosphate is also being investigated as a possible drug for COVID-19, according to the report.
The CDC is warning that the virus is likely to spread in the United States in the coming days. Fears of a large-scale stateside outbreak have already triggered a stock market selloff and the cancellation of countless business conferences, sporting events and concerts across the country.
Foreign nationals are prohibited from entering the U.S. if they recently visited China, and Americans returning from China are being told by health officials to “self-isolate” for two weeks.
“We have to recognize that we don’t know how the epidemic will end up,” Brechot said. “We have to be prepared for disseminaton and to prevent the worse-case scenario because we have already entered into a pandemic stage. But we don’t exactly know what the future holds.”
The professor said that rapid global urbanization has contributed to the severity of recent viral outbreaks and will continue to do so in the future.
“The truth is that homo sapiens have completely overhauled their ecosystem over the past few hundred years. That [timespan] is nothing when you put it in the context of human evolution,” he said.
Brechot is senior associate dean for research of global affairs at University of South Florida’s Morsani College of Medicine in Tampa. He is president of the Global Virus Network, an international coalition of virologists that fosters viral research and promotes epidemic preparedness. He formerly served as president of the Institut Pasteur in France.
Brechot disclosed that he serves as a consultant for Romark Pharmaceuticals, which produces an anti-parasitic drug under consideration for use in COVID-19 patients.