The Pros and Cons of Rapid COVID-19 Tests
When will the SARS-CoV-2 coronavirus be gone? Our primary care doctors in Delray Beach wish we knew the answer to that.
What we do know is that it’s still circulating among us, especially here in South Florida. According to the latest Centers for Disease Control and Prevention (CDC) figures, all South Florida counties except Okeechobee remain in the highest of three COVID-19 community levels.
The high categories reflect surging cases, positivity rates, and hospitalizations. WPTV reports that cases statewide are at the highest level since mid-February, the positivity rate of 17.2 percent is the greatest since early February, hospitalizations are the most since February 23, and the increase in deaths is the highest in the United States, which is still currently seeing an average of 327 deaths a day.
So we can’t let our guard down yet. This means continuing to wear masks in poorly ventilated indoor spaces, being current on your vaccinations, and testing if you think you’ve been exposed or have symptoms suggesting you might have COVID-19.
But do tests work?
Many people don’t bother to test, because they’ve heard the rapid antigen tests aren’t reliable. But that’s not necessarily the case. While not as sensitive as the PCR tests that have to be sent away to obtain results, they have proven to be a useful tool in the fight against the coronavirus.
For example, one study published last month in the journal JAMA Network Open found that the rapid tests caught 63 percent of positive cases, meaning they produced a large number of false negatives. Not a very good record, right?
However, when used on those who were symptomatic, the rapid tests caught 78 percent of cases among those with symptoms, and 39 percent of those who were asymptomatic. In addition, the tests were 100 percent accurate in those who didn’t have COVID-19.
The tests were conducted by the Stanford University School of Medicine among 700 Stanford University athletes upon their return to campus. Those who tested negative along with some who tested positive were also given the more reliable PCR tests.
Why all the misses?
In explaining the results, the study’s lead author Calvin Hwang, a clinical assistant professor at Stanford University, said the sensitivity of the tests appear to depend on the amount of viral load present in the subjects.
“These asymptomatic patients or pre-symptomatic patients, their viral load may not be high enough to be seen on a rapid test, and thus you get the problem of false negatives,” he said in a statement.
But they can also tell you when you might be contagious to others.
“Only the people shedding the most virus are going to be positive with a rapid test, but those are the people you especially want to identify because they’ve the most infectious,” Sheldon Campbell, an associate professor of laboratory medicine at the Yale School of Medicine, told NBC News. Campbell was not involved in the research.
Michael Mina, a former Harvard University epidemiologist and the chief science officer for the at-home testing company eMed, who was not involved in the study, told NBC that people who are negative on a rapid test might still be mildly infectious, but “they’re not going to be superspreaders,” he explained.
“They’re not going to go off into a locker room and infect 15 of their teammates,” he added.
What should you do?
If you think you have COVID-19 despite a negative rapid-test result, don’t just depend on that. Kaz Nelson, an associate professor of psychiatry and behavioral sciences at the University of Minnesota Medical School, told The Washington Post that people should also consider their physical symptoms, exposure risk, and the community rates of spread, which are high here in South Florida.
“Those are all the sources of information that you want to consider in how you make choices about your behavior,” she said.
That includes repeated rapid tests if you think you’re infected.
“If you test repeatedly, a rapid antigen test will detect you as soon as your viral load gets high enough that you actually become a risk to other people,” Mina told NBC.
“If I’m still positive, I should just not leave isolation. If I become negative, then I’m probably safe,” he said.
And the value of testing is not just to protect others, Campbell told NBC.
“If you’re a person at risk for severe COVID disease, I don’t think you should stop with the antigen test because we can treat you,” he said.
Remember long COVID
Surviving a bout with COVID-19 isn’t the only consideration, especially among seniors. Research suggests that seniors are more likely to develop the debilitating symptoms of long COVID than younger or middle-aged adults, according to The Post.
“Common symptoms, which can last months or years, include fatigue, shortness of breath, an elevated heart rate, muscle and joint pain, sleep disruptions, and problems with attention, concentration, language, and memory—a set of difficulties known as brain fog,” the paper reported last month.
So our primary care doctors recommend you continue to take steps to avoid contracting COVID-19, and to test yourself if you think you may have it. If you haven’t already done so, you can get your free tests online, or by calling 1-800-232-0233 (TTY 1-888-720-7489).
And let us know if you test positive, or test negative and still think you may have COVID-19. The sooner you begin treatment, the more effective it will be.
