The United States is on target for 50,000 deaths from the coronavirus by the end of this week as the number of infections are set to surpass 1 million in the coming weeks. It’s a sobering reminder that, despite the decline in newly reported cases, Americans remain at risk.
There is a clear risk of a second wave of the pandemic coming with the relaxation of shelter-in-place orders.
At the same time, with 26.5 million people losing their jobs over the past five weeks, there is an increasing urgency to reopen the economy.
But the idea of reopening the economy is somewhat of a misnomer. The economy will not return to normal all at once, and there is a clear risk of a second wave of the pandemic coming with the relaxation of shelter-in-place orders around the country.
Since some governors are in the process of relaxing these restrictions, we thought this is the perfect opportunity to discuss the risks around those decisions by using our mathematical model that predicts the infection rate, known as the fitted curve.
The basic model divides the population into three groups:
- S, for those who are susceptible to the virus
- I, for those who are infected
- R, for those who have recovered
The New York Times reported on several of the U.S. pandemic models, most suggesting that there is a long way to go before the virus and the subsequent deaths are brought to an end.
What we’ve found interesting in our model is that the parameters of the spread and the morbidity rate change over time as the public response and the location of the disease move from state to state. For this reason, we are reluctant to predict a long-term course for the infections, which is why we limit our projections to about a week.
We expect that the total number of cases will reach about 900,000 by the end of the week. That could all change should more governors attempt to roll back the shutdown. The experience of the virus’s spread in Seattle suggests that it would take only one ill-conceived gathering to reignite the spread among other communities.
The next phase
So when will it be safe and productive to reopen the economy? And how do we get there? Here’s what we do know.
First, it’s unwise to believe in medical treatments that are not proven. Take the anti-malarial drug hydroxychloroquine, which until recently was aggressively promoted as a possible treatment. Gradually, a clearer picture is emerging. Preliminary results from a study of U.S. veterans funded by the National Institutes of Health and the University of Virginia recently found “no evidence” that use of the malarial drug hydroxychloroquine, on its own or in conjunction with another, “reduced the risk of mechanical ventilation in patients hospitalized with Covid-19.” The research found that the death rates were higher in patients treated with hydroxychloroquine alone.
A broad national and state program of testing is needed.
Second, a national and state program of testing is needed; first to determine who is infected and who remains susceptible – the S in our model — so that they can be isolated, and then to determine if those who have recovered – the R — have developed an immunity that would allow them to safely return to the workforce. At the same time, that test would provide the basis for research for a distribution of a vaccine such that susceptible people — even if they cannot safely take the vaccine – could reenter the community without fear of infection.
In an article in the Journal of the American Medical Association, the microbiologist Florian Krammer of Mount Sinai’s Icahn School of Medicine in New York talked about the development of a test and said, “What we’ve found with our test is that basically everybody’s naïve. There’s no preexisting immunity. And that makes it very easy to distinguish between people who have been infected and who haven’t been infected.”
Two types of testing: Molecular and antibody
There are two types of testing. The first is molecular testing (swabs of the mouth and nose) for the diagnosis of Covid-19 in symptomatic patients. In the same JAMA article, Elitza Theel, director of the Mayo Clinic’s Infectious Diseases Serology Laboratory, said that these kits are “cheap and easy to use and, depending on how they’re employed, may be helpful for disease surveillance.” Theel added, “Molecular testing is still going to be the go-to preferred method for diagnosis of Covid-19 in symptomatic patients.”
The second test type is antibody testing, a blood test that detects previous exposure to the disease. A virus emits a toxin (a molecule known as the antigen) that attacks the body’s functions, in this case the lungs. The immune system responds to the attack by producing antibodies to counter the antigen’s attack. An antibody test can reveal “markers of immune response… that for most people show up in blood more than a week after they start to feel sick, when symptoms may already be waning,” the JAMA article said.
The consensus of experts is that antibody testing should not be used to diagnose active cases. Rather, the purpose is to find those antibodies that can be used to formulate a vaccine and to identify and continue to provide testing for the immunity of those members of the population who might safely return to normal activity.
For example, if 50% of the population were exposed to the virus and had developed an immunity, that could conceivably be enough to restart half the economy.
Is there a model for a program of antibody testing? Look to Germany.
A recent NPR report listed a broad program of antibody testing in Germany, “which produces most of its own high-quality test kits” and “is testing for Covid-19 on a greater scale than most countries: an estimated 120,000 tests a day in a nation of 83 million.” There is no reason why U.S. industry cannot be asked to do the same.
And then the BBC reports that while antibody testing is in the works, a reliable test kit still needs to be found, and there are important caveats that should not be ignored.
Those caveats would include those outlined by Theel of the Mayo Clinic: “I think that it is very important that we understand the limitations of serologic testing, recognizing that it takes time to mount a detectable immune response, and to use them for the right reasons…a false-negative serologic result in an acutely symptomatic patient with replicating and shedding virus has serious public health consequences.”
There is not enough evidence to simply assume that an antibody’s past response to the virus will prevent reinfection or that the test result is not biased because of the presence of other immune-system characteristics.
The JAMA article told of clinical antibody testing taking place at Mount Sinai and the Mayo Clinic, which could lead to wider testing and an eventual gradual reopening of the economy. But there should be caution. Krammer said. The U.S. is just at “beginning of a large epidemic,” Krammer said, which implies a recovering population of insufficient size to support the return to normal activity.
A simple step that could save lives
Dr. Richard Levitan of Bellevue Hospital in New York offered one solution in an opinion piece in The New York Times: “There is a way we could identify more patients who have Covid pneumonia sooner and treat them more effectively — and it would not require waiting for a coronavirus test at a hospital or doctor’s office,” he wrote. “It requires detecting silent hypoxia early through a common medical device that can be purchased without a prescription at most pharmacies: a pulse oximeter.
“Pulse oximetry is no more complicated than using a thermometer. These small devices turn on with one button and are placed on a fingertip. In a few seconds, two numbers are displayed: oxygen saturation and pulse rate. Pulse oximeters are extremely reliable in detecting oxygenation problems and elevated heart rates.”
One solution is for the U.S. government to use its powers to compel American industry to produce a pulse oximeter for every household. Even if the coronavirus were to behave like a typical influenza and retreat for a time, the probability of a second wave of the pandemic cannot be ignored.
The need to get the economy reopened and instill confidence among the public that it can again restart individual, social and business activity is paramount.
For more information on how the coronavirus is affecting midsize businesses, please visit the RSM Coronavirus Resource Center.
