Photo by Aaron Lavinsky, StarTribune, via Getty
By Melissa Patrick
Kentucky Health News
Health experts say more coronavirus testing — both for the virus itself and for antibodies that show whether a person has been previously infected — is needed before the nation and the states consider relaxing social-distancing rules and “reopening the economy,” as President Trump says he wants to do.
“How we are able to move forward very much is dependent on having access to the right information, and clearly testing is essential for all of this,” Dr. Jennifer Nuzzo said during a Friday media conference held by SciLine, a science-information service for journalists.
“All of the game plans for the next phase really come up against a hard limit — which is not being able right now to expand testing, given limitations in supplies and other things like that,” Nuzzo said. “We very much need to be able to do that in order to move forward.”
Nuzzo is a senior scholar at the Johns Hopkins Center for Health Security and an associate professor of environmental health and epidemiology at the Johns Hopkins Bloomberg School of Public Health.
She cautioned that moving from the current social-distancing strategy to slow the spread of the virus would surely increase covid-19 cases.
“In order to make decisions about when and how to lift social-distancing restrictions, we need to have better surveillance both for the disease and also for the impact on the health system,” she said. “And right now we have very little surveillance on the health system and quite imperfect surveillance for the disease.”
Nuzzo, like Centers for Disease Control and Prevention Director Robert Redfield, said the next phase of dealing with the pandemic in the U.S. must include more testing as well as a move to what she called “case-based measures,” a labor-intensive, tried-and-true public health measure that identifies individuals who have the virus, places them in isolation, locates all of their contacts and then monitors those contacts as well. This practice is also called contact tracing.
“These case-based measures are going to be essential for the United States in its next phase, because if we release our social-distancing measures, we will have to have a plan to deal with the rising cases,” she said. “Otherwise, it will just escalate again, potentially to the point where we were before we implemented these population-based measures.”
Nuzzo called for a national testing strategy, which she said would allow for a better understanding of what is happening across the nation, would better inform any plans going forward, and would eliminate some of the current bottleneck around supplies.
More than 30 different covid-19 tests are available, but states are still struggling to get enough of them, said Dr. Jana Broadhurst, director of the Nebraska Biocontainment Unit Clinical Laboratory and assistant professor of microbiology at the University of Nebraska.
“Despite this daily increase in the availability of diagnostic tools, that’s not translating into a similar rate of increase in our ability to actually deploy that testing and to get test results to physicians and public-health authorities as well as we need to do,” she said.
Gov. Andy Beshear spoke to the need for more testing at his covid-19 briefing Friday: “We are truly testing the very sickest right now,” and are so short of test kits that people who have been mildly symptomatic and wanted to be tested have been asked to “ride it out without a test.”
Not only are states still having to decide who to test based on resources available; there is still a need to ensure that the large platform of available tests are accurate and reliable, Broadhurst said, noting that the rate of false-positives is reported to be around 30 percent, and voicing concerns about the quality of specimens collected in drive-through locations or home-based testing.
“It’s just absolutely critical that there’s a way to ensure the quality of the specimen that is collected,” with the understanding that drive-through or home-based specimens may not be comparable to a specimen collected in a clinical setting, she said.
Another type of test, for antibodies to the coronavirus, may play a more important role in determining who will be allowed to go back to work because it is the only way the U.S. has to determine the virus’s infection rate.
“If their antibody test is positive, one can formulate strategies about whether or not they would be at risk or vulnerable to getting re-infected,” Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said on CNN Friday morning.
Broadhurst the antibody tests will initially be available only to front-line health workers, but the Food and Drug Administration approved the first such test last week, and “Within a period of a week or so, we’re going to have a rather large number of tests that are available,” Fauci said.
Eran Bendavid and Jay Bhattacharya, professors of medicine at Stanford University, also point to the importance of antibody tests as a way to determine the true infection rate in the U.S. and as a way to get people back to work.
“Given the enormous consequences of decisions around covid-19 response, getting clear data to guide decisions now is critical,” they write in an op-ed for the Wall Street Journal.
Bendavid and Bhattacharva say current estimates about covid-19 death rates may be too high because the “true fatality rate is the portion of those infected who die, not the deaths from identified positive cases.” They say that using this as the measure for death rates would result in a much smaller rate than the 2 to 4 percent estimated by the World Health Organization and others.
In other words, they say that if the number of actual infections is much larger than the number of cases identified, then the true fatality rate is much lower as well.
And if this is true, they write that this could mean measures focusing on older populations and hospitals would continue to be necessary, but “a universal quarantine may not be worth the cost it imposes on the economy, community and individual mental and physical health.”
Health officials also worry that as covid-19 testing increases, so too will the number of false negative results. “If you have likely exposures and symptoms suggest covid-19 infection, you probably have it, even if your test is negative,” Dr. Harlan Krumholz, a professor of medicine at Yale University, writes in The New York Times.
And as other health officials have pointed out, while a positive result is fairly reliable, a negative result can only confirm that that person does not have covid-19 on the day of the test, since the incubation period for the virus is up to 14 days.