The flu season has reached outbreak stage, and most of the severe impacts are with children, the Jefferson County health officer said.

Dr. Tom Locke said 60 tests at Jefferson Healthcare for the week ending Jan. 11 were 37 percent positive for the flu, and it’s predominantly Influenza B, the same strain the vaccine is meant to fight.

“Usually when the positivity is above 20 percent, that’s when we’re in outbreak mode,” he said.

Dr. Allison Unthank said the pattern is similar in Clallam County, where she is the public health officer.

She encouraged residents 6 months of age or older to get a flu shot.

“For most folks, it prevents infection,” Unthank said. “For those who do get infected despite getting vaccinated, it makes the illness less severe and less deadly.

“Further, it reduces transmission of the disease, preventing exposures of vulnerable people and preventing outbreaks. So overall, getting vaccinated is a good thing to do for your health and a really good thing to do for the health of your community.”

Locke presented data Thursday at the Jefferson County Board of Health meeting, and he called it a very unusual flu season.

“This is really widespread at this point,” he said. “It picked up before Christmas, which only happens about one year out of 10 (nationally). In the Northwest, it’s a little more common.”

Weekly statistics reported by Jefferson Healthcare from Sept. 22 through Jan. 11 show a three-fold increase in the number of tests and the percentage of positive results trending upward.

Those who are tested have symptoms such as a fever, cough or sore throat, Locke said.

“If they appear to have some type of respiratory infection, they get tested,” he said.

But it’s not always the flu.

“There’s a lot of other things out there, usually a half-dozen viruses at any one time that can be flu-like symptoms,” Locke said.

Locke described Influenza A as an avian virus that at one point jumped over to human strains. Influenza B is the human strain, he said.

“We usually regard it as a milder form than the A strains, but that’s not always true, so it’s always unpredictable, especially with children, and that’s how it’s playing out this year,” Locke said.

The current vaccine contains two strains of Influenza B, but “neither of them are a really good match,” he said.

“The virus mutated so that it’s no longer an exact match for the vaccine strain,” Locke said.

Unthank said health departments won’t know until the flu season is over how effective a particular vaccine has been. The efficacy data is tracked by the Centers for Disease Control and Prevention, she said.

Locke said the flu shot for the 2018-19 season was 38 percent effective nationwide.

“If we were to guess, this has all the markings of the bi-modal season, where there is an initial peak, then it drops off, and then you get a second peak,” Locke said.

Greg Brotherton, the chair of the Jefferson County Commissioners, asked if the health board should continue to urge people to get flu shots.

Locke said yes.

“On a population basis with millions and millions of people, that substantially changes outbreaks,” he said.

Vaccines are much more effective for children and young adults who have good immune systems, Locke added.

“Clearly we need a better vaccine, but even 38 percent is better than 0 percent, because it’s a very safe vaccine,” he said.

One of the problems Locke sees with the flu shot is that it isn’t very good for stimulating immunity, he said.

“There’s some more effective vaccines that are being used for 65 and older populations,” Locke said. “They appear to be more effective, but we only have the numbers from small studies to document that.”

Jefferson County Commissioner David Sullivan asked if those vaccines could be produced at a rate they could be used for everyone, and Locke confirmed, although he said it would be more expensive to make.

Locke also said people likely would experience more symptoms.

“By producing more of an immune reaction, they produce more side-effects,” he said. “That means more of a sore arm and probably a low-grade fever.”

Unthank said the CDC data after the flu season is complete will help guide the production of the next vaccine.

“Dr. Locke and I are in agreement that, while we can never know exactly how effective a flu vaccine will be until after that season has passed, it remains the best defense we have against the flu,” she said.