The COVID-19 transmission rate in Missoula County remains below other hard-hit counties in Montana, though nearly half of all local cases still stem from those aged 20 to 29, health officials said this week.

Missoula City County Health Officer Ellen Leahy said the infection rate among the younger crowd is significant given that school is ready to commence for the fall semester.

“We still have one-third of our active cases derived from the age group 20-29,” she said. “That is an age group where often the symptoms are very mild or absent, and it's difficult for folks at that age to know they're infected and contagious.”

As of Tuesday morning, Missoula County reported 80 active cases and 333 close contacts. Three people were currently being hospitalized.

“In terms of the 80 active cases we have, the largest source is actually close contact to a case,” Leahy said. “That's actually a good sign. That's 26% of our cases right now, derived as close contacts to a previous case.”

Leahy said the figure indicates that those who became infected were able to identify who they had contact with two days prior to the onset of their symptoms. That made contact tracing easier.

“It's one of our major control strategies for the pandemic,” she said.

But the next largest group of cases derives from community spread. That makes it hard to determine where the infection was caught, and harder to trace any known contacts.

While new averages are expected this week, Leahy said the transmission rate in Missoula County is holding in a plateau. The local incidents per 100,000 people over a 14 day average sits at around 36.

In comparison, Yellowstone County has a transmission rate of around 279 over the same span, and Big Horn County is at 1,129.

Ravalli County is at 24 and Lake County is at 38, Leahy said.

“Since we draw workers and students and our healthcare workforce into Missoula County from surrounding counties, we appreciate it when folks from surrounding counties cooperate with the requirements and recommendations we have here,” Leahy said.

Missoula County health officials and epidemiologists from the University of Montana have scheduled a press conference on Wednesday to discuss the latest trends.

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