Defining 'Infectious' During COVID-19: It's About Timing

Jul 28, 2020

The overall caseload of COVID-19 in Lane County increases daily, yet the number of 'active' or 'infectious' cases has not changed at the same rate. Public Health officials have an explanation.

Oregon Health Authority and the Centers for Disease Control and Prevention determine it is rare the coronavirus can replicate nine days after symptom onset. Lane County Public Health waits for 10 days before removing a case from the 'infectious' column.
Credit Centers for Disease Control and Prevention

“Infectious” is currently defined as having enough of a viral load to be a transmission risk. LCPH Spokesperson Jason Davis said it’s all about timing.

“The average time from when you are exposed to when you start developing symptoms is between 2 and 4 days,” he said. “Then- when someone is tested or we label them as a presumptive case-- we count 9 days, or 10 days to be safe, from the date that they had that symptom onset.”

After that period- novel coronavirus rarely replicates. People may remain sick, but viral loads diminish.

Davis says sometimes Lane County Public Health will be notified of a positive test result well after the infectious date for that case has passed. So, it goes in the overall case column only. There are currently 35 cases labeled infectious in Lane County.

The overall case total as of 07/28/2020 is 464.      

During a LCPH briefing, spokesperson Jason Davis (right) explains the definition of 'infectious' and when the label is applied to cases.
Credit Lane County Public Health video