Health board opposes publicizing metric associated with coronavirus tests

The Lincoln County Health Board has voted against publicizing cycle thresholds, a metric that some board members argued could provide a more nuanced look at the severity of coronavirus infections but public health experts say can be dangerously misleading when diagnosing patients.

Cycle thresholds refer to the number of cycles required to amplify viral RNA to a detectable level in polymerase chain reaction (PCR) coronavirus tests. Although the cycle threshold associated with a PCR test is a quantitative metric, the person taking the test will only receive a qualitative result; either they will test positive or negative for the virus.

During a June 8 meeting, Josh Letcher, county commissioner and health board member, said that withholding cycle thresholds linked to a PCR test would be the equivalent to concealing blood alcohol levels associated with breathalyzer tests. Debra Armstrong, Eureka’s representative on the board, backed Letcher and said that judging the severity of a person’s coronavirus infection based on cycle thresholds could cut down on quarantines and help keep businesses open.

But health officials at the meeting found fault with this reasoning. Amy Fantozzi, board member and healthcare provider, had trouble seeing how local healthcare workers would apply the cycle thresholds when dealing with patients infected with the virus.

“It doesn’t change [the patient’s] positive or negative result,” she said. “The positive or negative is what needs to be recorded because that’s what matters to the people around them.”

Dr. Brad Black, county health officer, agreed, saying PCR tests were meant to be used as quantitative tests.

“We can’t let it become something else or once the [cycle threshold] value gets up there, the misuse of it could be high,” he said. “You could have very detrimental effects from a public health standpoint.”

Board member Dr. Sara Mertes, echoed concerns about the clinical applications of cycle threshold values and scrutinized the wording of the action item the board was considering. The measure would have required county officials to include cycle thresholds in public records whenever using PCR tests as part of “epidemiological studies to justify any public health decision.”

Mertes noted that county officials were not conducting epidemiological studies. When making public health decisions in regards to the pandemic, local authorities had relied on guidance from the state.

“When we look back at what decisions were made regarding COVID[-19] and quarantine and masking and all these things, really very little of that, if any, was made at the local level,” she said.

Jim Murphy, an administrator at the state Department of Public Health and Human Services, said that many factors beyond the severity of a person’s infection play a role in cycle thresholds. The collection method used by the healthcare worker administering the test and the age of the sample can have a significant impact on the metric.

“We can have a radically different … value on somebody with two samples taken the same day because one sample might be a really well-taken sample,” said Murphy. “The other might have been maybe not a high-quality specimen or maybe even just sat for a day or two longer before it was run.”

Due to these variations, officials with the Centers for Disease Control and Prevention have cautioned healthcare providers against using cycle thresholds to judge the severity of a person’s coronavirus infection. The CDC and Association of Public Health Laboratories have even indicated that including cycle thresholds in patient reports could be a regulatory violation since officials have only granted emergency use authorization to PCR tests, according to Murphy.

While not clinically valid, cycle thresholds can be useful in laboratory settings. When searching for variants of the coronavirus, Murphy said researchers often will rely on the metric to judge the quality of the sample.

Armstrong pressed Murphy on why the CDC was recording PCR cycle thresholds for breakthrough cases, or instances where patients had become infected with the virus after receiving vaccine doses.

When the first breakthrough cases occurred, Murphy said healthcare officials had been diligent in following up with each patient. Since then, the CDC has gathered enough information that officials will only follow through on serious breakthrough cases in which a patient is hospitalized or dies. In these cases, Murphy said researchers want to collect a good sample of the virus and thus will refer to the cycle thresholds associated with tests.

“They don’t want us to waste our time with the higher threshold values because we’re less likely to get a decent result from the whole genome sequencing which is an elaborate and fairly expensive process,” he said.

During the public comment section of the meeting, resident Diane Watson echoed Armstrong’s concerns that inaccurate results from PCR tests could severely impact the livelihood of local residents. Murphy said he understood these worries, noting that, as with any test, errors in the laboratory and contamination issues could yield false positives in PCR tests.

“Any healthcare provider worth their salt is going to look at that test result in coordination with what is going on with the patient,” Murphy said. “We’ve always encouraged any provider that feels that this doesn’t match the clinical scenario to repeat testing.”

But Murphy pointed out that PCR tests have proven remarkably accurate.

“The PCR test is the best test that we have, in this country or worldwide,” he said. “It is considered the gold standard for this.”

The health board voted three to two against the motion. Armstrong and Letcher cast the assenting votes.