When will Whatcom Co. flu season peak? What to know about flu, concerning winter illnesses

Flu transmission typically peaks in the winter, both in Washington and in the U.S. as a whole. As the calendar inches closer to February, transmission levels are high across the state, but could subside soon.

We reached out to Whatcom County health officials to see what the outlook is for the rest of flu season in the area. Here’s what they had to say.

Winter illnesses in Whatcom County

Whatcom County Health and Community Services maintains a dashboard of respiratory illness data. While the data isn’t broken down by specific illness, respiratory illnesses as a whole are down this winter compared to previous years.

So far, Whatcom County has seen one death from the flu this winter. In the first week of January, 14.4% of Whatcom County emergency department visits have been caused by an acute respiratory illness, compared to 16.1% at this time last year and 16.7% the year before.

“When we look at COVID-19, [respiratory syncytial virus], and flu, so far this winter season we have not seen abnormally high hospitalizations or emergency department visits compared to previous winters,” Marie Duckworth, public information officer for Whatcom County Health and Community Services, told the Bellingham Herald in an email.

When will flu season peak?

Additionally, the Washington State Department of Health maintains data on each individual illness, and while it’s not broken down by county, it is broken down by region. In the North Sound region, which includes Whatcom County and is published on the county dashboard, 2.9% of all hospitalizations across the first full week of January were attributed to the flu, up from 2.6% the week before but still below the season’s peak of 3.2%.

Even with the slight decline in late December, the flu hospitalization rate in the region is still much higher than last winter’s peak of 1.7%, although it’s nowhere near the peak rate from two years ago, 8.3%, according to the county dashboard.

The percentage of emergency room visits caused by the flu, meanwhile, have fallen for two consecutive weeks to 3.5% from a peak of 4.7%. Both figures are higher than last winter’s peak of 3.0% but below the 13.6% rates seen two winters ago.

According to Duckworth, Whatcom County has seen similar trends.

“Influenza levels have been slightly higher this winter than last, but It appears that all three viruses have peaked and are now starting to decline in Whatcom County,” Duckworth said.

Whooping cough and walking pneumonia cases are high

The flu isn’t the only respiratory illness to hit Whatcom County this winter, though. According to Duckworth, the state has seen a surge in cases of a pair of other illnesses.

“This winter, there has been a large increase in some bacterial respiratory illnesses — specifically pertussis, commonly called whooping cough, and a type of bacterial pneumonia commonly called walking pneumonia.”

Walking pneumonia, which usually causes symptoms more often associated with a bad cold than a bout of pneumonia, has been on the rise across the state and the country, especially among children.

Pertussis is also spreading at an high rate in Washington, but Whatcom County has been hit especially hard.

On the heels of a year when Washington saw the most cases of the illness since 2012, Whatcom County saw pertussis spread at a rate of over one case per 100,000 people over the most recent six week stretch on record, according to DOH’s weekly pertussis update.

As of late December 2024, the county had seen 175 cases of the illness, the fourth-highest in the state. Its rate of 75.5 cases per 100,000 residents over the course of the whole year was the sixth-highest of Washington’s 39 counties, according to the DOH report.

“Whatcom County Health and Community Services saw a significant increase in pertussis cases starting in October, and we investigated high numbers of Pertussis in November and December too... In 2024 we saw the highest rates of pertussis that we have seen in the last ten years,” Duckworth said.

The illness can present as a common cold but is often characterized by a severe cough.

“This disease starts like a cold but then can progress to serious illness, especially for babies and people with significant lung conditions,” Duckworth said. “Vaccination can keep someone from getting sick, or they may only have mild symptoms. Without any protection, even otherwise healthy people can develop a very prolonged miserable cough.”

You could be vaccinated even if you don’t realize it, since the immunization is included in the common Tdap vaccine.

“The best way to protect babies and other vulnerable people is to get vaccinated, get treated quickly if you are infected, and stay home from work, school, or daycare until you are no longer contagious,” Duckworth said.