With a shortage of COVID-19 lab tests, North Carolina is pivoting in how it tracks the spread of the virus. The state plans to use syndromic surveillance to track COVID-19 — deploying the system it uses to monitor the seasonal flu for the coronavirus.
The state plans to continue a “high volume” of testing, but it will also now rely on patients’ reported symptoms to track the coronavirus. It will track hospital admissions for acute respiratory illness and reported instances of “fever cough syndrome,” said State Epidemiologist Dr. Zack Moore in a press conference Monday, March 30.
North Carolina had 1,307 confirmed cases, 137 hospitalizations, and six deaths, as of Monday morning. Gov. Roy Cooper declared a 30-day statewide stay-at-home order to slow the pandemic.
The U.S. Centers for Disease Control and Prevention has been blasted for delays and test shortages. The first tests from the CDC weren’t reliable, and testing has since been plagued with shortages of chemical reagents and swabs.
North Carolina had completed 20,864 tests, as of Monday morning. That has more than doubled since a week ago, when there were 8,438 completed tests.
“There are limits nationally not only in testing supplies, but perhaps more importantly, in personal protective equipment that is so important for protecting our health care workers and patients,” Moore said. “We need to rely on some of our other evidence based methods and tools to track this effectively.”
The state is repurposing networks that track seasonal influenza. The CDC runs the Outpatient Influenza-like Illness Surveillance Network — the clinical sites scattered across North Carolina and the nation that traditionally collect data on influenza. Now, the network will also track the coronavirus.
“Laboratory testing is critical, and will continue, but this allows us to get at people who present for medical care with symptoms but don’t get testing,” Moore said. “This gives us a more stable set of specimens and a stable way of looking across the state.”
The state can’t rely only on laboratory confirmed cases to monitor the coronavirus, says Moore. He compared the coronavirus to an iceberg, where the visible, confirmed cases are only a fraction of a larger mass.
“Laboratory confirmed case counts are never the whole picture,” Moore said. “People need to realize that this applies to them, whether or not there is a confirmed case in their county or not.”
But using syndromic surveillance does have its weaknesses. The system will only flag the people who ask for medical care, and it could miss mild or silent cases of COVID-19.
“We do recognize that these are based on people who need medical care,” Moore said “They don’t capture people who don’t seek medical care, who have general symptoms or no symptoms at all. We’re learning what percentage of COVID-19 cases that is.”
The state has considered using random sampling to discover that percentage, but such testing would have to be done in a scientifically rigorous way — meaning tests would have to be repeated and carefully considered. The state does not yet have a reliable random antibody test to discover how many people have recovered from the virus.
“We have to acknowledge that we’re just in the beginning,” Moore said. “There is every indication that it is really ramping up now. We’re in the acceleration phase of the virus here in N.C. We certainly have not peaked.”