In addition to the persistent anxiety about becoming sick due to COVID-19, some people have claimed that these new variants can’t be detected by over-the-counter COVID tests. This claim is false.
With the struggle to combat COVID-19 moving into its fourth year, some have wondered whether current tests have fallen behind the changing nature of the virus. To answer that question, the AmNews spoke with Dr. Joseph Petrosino, chair of molecular virology and microbiology at Baylor College of Medicine. According to Petrosino, even though much has changed with COVID-19, the tests haven’t gotten less effective, and manufacturers are continually checking their tests against new variants.
“When the new variant comes out, it’s isolated, it’s grown in the laboratory, or samples from patients that have the specific variant are collected and then applied to the test,” said Petrosino. He further explained that if test makers see that their test performs poorly on a new variant, they’ll update the test to respond.
However, that has not happened with the SARS-CoV-2 virus. A study published in Scientific Reports showed that COVID-19 rapid tests have remained stable over three major variants.
The current dominant strain of COVID being seen throughout the United States is JN.1, with 86.5% of cases, followed by JN.1.13, with 9.5% of cases. Petrosino explained that a test designed years ago can detect a COVID strain that emerged only months ago, which has to do with what makes a strain a strain.
Virus particles contain several proteins, such as the spike protein that allows the virus to enter someone’s cells, and others, such as nucleoprotein. A strain is named based on changes to the spike proteins, but Petrosino noted that coronavirus nucleoproteins don’t change nearly as often. “So, while the spike proteins are changing rapidly…to evade immune responses and still adhere to human cells, the nucleoprotein isn’t involved in those processes.” According to Petrosino, “there’s no pressure for it to change, so it stays relatively consistent—the same.”
As a result, rapid COVID-19 tests are designed to detect the stable nucleoprotein, rather than the fast-changing spike protein. Petrosino said that “if you did make a test [for] the spike protein, then yes, you would have this issue where the test would become obsolete every time a new variant emerged.”
But if the tests haven’t changed, why do some people think like they have? The answer may have less to do with how the virus has changed than with how we’ve changed. The past few years have built up immune systems, which now can keep the virus undetectable for a greater duration of time. Because “immune responses are becoming more advanced, because of vaccination and previous exposures to the various COVID variants, the duration…becomes longer, the level of virus stays lower early on,” Petrosino said. As a result, people who suspect they have COVID may need to wait two to three days before a rapid test gives them a positive result.
While polymerase chain reaction (PCR) tests are the “gold standard,” rapid tests can give a false negative result 30–45% of the time, depending on how they’re administered. While by no means perfect, the rapid tests do still serve a function. Given that home tests can provide false negatives, “they’re built to be taken multiple times,” Petrosino said. “If you have been exposed, or you do feel like you do have symptoms, and you do test, and you turn out negative, then the CDC guidelines would say, ‘If there’s a need… test again.’”
It is important to note that at-home COVID test kits are labelled with expiration dates, and generally should not be used beyond those dates. In some instances, the expiration date has been extended. A full collection of at-home COVID-19 test kit expiration statuses can be found on the FDA’s website.
For immune systems to change over time is not surprising. “It’s just a natural thing that happens in the course of… a pandemic, where the virus is evolving…we’re getting better at being protected against the virus,” Petrosino said. “The virus levels stay low… that’s going to have an increase in false negatives…The key now is to continue testing.”For additional resources about COVID-19, visit www1.nyc.gov/site/coronavirus/index.page or call 311. COVID-19 testing, masks, and vaccination resources can also be accessed on the AmNews COVID-19 page: www.amsterdamnews.com/covid/. To get free COVID tests, visit the City of New York’s webpage and the NY Health and Hospitals webpage. For those who may be suffering from the long-term effects of COVID-19, a list of post-COVID clinics in NYC can be found at nyc.gov/assets/doh/downloads/pdf/covid/covid-19-care-clinics.pdf.