Measures to slow the spread of the novel coronavirus brought an extra bonus to Seattle and King County: Reduced levels of respiratory infections of all types.

A new analysis of results from the Seattle Coronavirus Assessment Network (SCAN) finds that the respiratory viruses responsible for everything from common colds to flu were much less prevalent this year than in 2019.

“The undeniable contrast is almost certainly due to the COVID-19 control efforts,” says a blog post by researchers Gregory Hart and Mike Famulare of the Institute for Disease Modeling.

SCAN is a project to monitor COVID-19 infection levels across the county. It’s modeled after the Seattle Flu Study, which began tracking a variety of respiratory bugs in 2018, providing baseline data and detecting the first community transmission of the novel coronavirus in Washington.  

Volunteers swab their own noses and send the specimens to a lab at the University of Washington for analysis, which includes tests for multiple viruses like the rhinovirus and common coronavirus responsible for many colds and sniffles, and respiratory syncytial virus, which can be dangerous for children and older people.

Flu season was already winding down when the pandemic hit. But after many major employers instituted work-from-home-policies and Washington’s “Stay Home, Stay Healthy” measures were imposed, flu cases plummeted along with other respiratory infections — including viruses that normally circulate all year.


“Clearly, it makes a lot of sense when you think about it biologically,” said Dr. Steven Pergam, an infectious disease specialist at the Fred Hutchinson Cancer Research Center and director of infection control for Seattle Cancer Care Alliance. “If you’re not in as much contact with others, that can really decrease the rates of transmission.”

The data also suggest that as the county began loosening restrictions, viral infections remained low thanks to the statewide mask mandate imposed in late June.

“The same steps we take to prevent COVID-19 — limiting activities outside the home, decreasing the numbers and duration of close contact with others, avoiding poorly ventilated spaces, wearing a mask whenever in public, and good hand washing — will also help reduce the spread of influenza and other respiratory viruses,” said Dr. Jeff Duchin, Health Officer for Public Health — Seattle & King County.

If mitigation measures for COVID-19 remain in place into the fall and winter, the 2020-21 flu season could be quite mild, the researchers write. This year’s flu season in the Southern Hemisphere has been extremely light so far — possibly due to coronavirus countermeasures.

But it’s also possible that flu and other viruses will flourish as they usually do when the weather turns chilly, partly because people are forced to spend more time inside. Positive tests for rhinovirus are already increasing, though levels are still lower than last year.

“The most likely conditions that would undermine the dampening of flu transmission are the same that would undermine COVID-19 control — particularly if indoor crowding goes up too much when the weather is wet and cold,” Famulare said in an email. “Flu will likely be more controllable while COVID-19 mitigation efforts continue.”


With so much uncertainty, and the possibility of overlap, confusion and interaction between influenza and COVID-19, it’s more important than ever to get a flu shot this year, Pergam said.

“We don’t really know what’s going to happen,” he said. “Flu is a deadly disease and whatever we can do to prevent people from getting sick is a huge benefit to hospitals, to the individual and to our community.”

Experts recommend getting the shot, which takes a couple of weeks to kick in, by the end of October. Efforts are underway to make the vaccine more accessible this year, and Pergam said he’s hearing from local pharmacists that demand is already high.

Many drugstore chains, including Bartell Drugs, have ramped up their immunization programs to fill the gap left by workplace clinics, which are mostly nonexistent this year. Pharmacies are scheduling appointments to reduce the risk of exposure to COVID-19 from standing in line. ZOOM+Care clinics across the state are offering five-minute appointments with minimal contact with others.

In collaboration with Public Health — Seattle & King County, the Seattle Visiting Nurse Association is staffing drive-thru clinics in several locations. Through Wednesday, Sept. 30, they’ll be at North Seattle College. Beginning Monday, Sept. 21, they’ll be at ShoWare Center in Kent. They accept most insurance, including Medicare and Medicaid/Apple Health, and patients can register at