SACRAMENTO (CBS13) — Delayed results from the state’s troubled COVID testing lab forced some schools to cancel their football games Friday. Other teams decided to get last minute rapid tests from another lab before the game and they got to play.
Now, two of those teams are quarantined because, when the state’s results finally came in on Sunday, a player who had a negative rapid test Friday got a positive result from the state lab.
Is it possible that both tests were accurate?
“It certainly is possible,” said Dr. Mark Pandori, director of Nevada’s State lab.
He explains that PCR tests are highly sensitive. Some argue too sensitive, in fact.
Both rapid antigen tests and PCR tests are allowed under California youth sports guidelines. PCR tests from the state lab are generally cheaper.
While PCR tests were considered the gold standard because they detect very low levels of the virus, Pandori points to data from the CDC and others that indicate low-level PCR results are not likely contagious.
“We believe that these low viral load specimens might pose either no or considerably less threat to public health,” said Pandori.
Meanwhile, rapid antigen tests are not as sensitive, so they generally don’t detect those low levels.
“So it’s possible the negative rapid test and the positive PCR test were both accurate and the players’ virus levels were so low that it wasn’t a threat to public health?” asked CBS13 Investigative Reporter Julie Watts.
“It’s not only possible but, in my experience, that’s the most likely explanation for it,” Pandori said.
According to PerkinElmer, their PCR test, used at the state lab to test the football players, is the most sensitive test on the market and can detect extremely low levels of virus.
Pandori and others note that the PCR tests may be detecting RNA from virus fragments, not necessarily live virus.
“So, when it comes to youth sports, are we at risk of quarantining entire teams, even classrooms, based on irrelevant levels of virus?” Watts asked.
“The science is not 100% completely clear on this yet,” Pandoir clarified.
He says, for now, public health officials need to err on the side of caution when PCR and rapid results differ. It is possible to get a false negative rapid test, and because they’re processed outside the lab, they may be more prone to human error.
However, PCR tests can return wrong results too and contamination can lead to false positives.
“Whether you get an antigen test or a PCR test at this point, you’re probably in pretty good shape in terms of creating an accurate reflection of threat,” Pandori said.
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