Flu Cases Climb in Oregon

Flu cases are on the rise across Oregon and the Pacific Northwest, complicated by a vaccine that’s less effective on one of the dominant strains this year. And it’s still too early to tell when the season will peak.

The number of flu cases in Oregon rose sharply at the end of December, but it’s still too soon to tell when the season will peak.

From October to the end of December, the state had 335 influenza-associated hospitalizations - with the biggest spikes in cases seen in recent weeks. But the boundaries of the typically three-month season can be a little hard to define, and the spikes in cases could still be growing, said Ann Thomas, public health physician at the Oregon Health Authority.

“It’s gone up rapidly in the past few weeks,” she said. “We’re experiencing heavy activity and I hope it comes down soon.”

From December 17-23, Oregon had 123 influenza-associated hospitalizations, up from 85 the week before, which is the most recent data published on Dec. 29 in the state’s Flu Bites newsletter. It’s harder to track mortality accurately along with those stats because flu deaths are often complicated by pneumonia and other illnesses, Thomas added.

Washington state, which tracks the stats a bit differently, confirmed 20 influenza deaths at state labs and found 16 influenza-like outbreaks at long term care facilities in the 2017-2018 season as of December 23.

Part of the reason the statistics look different in different states is that influenza is not a reportable disease, so there are no mandatory requirements for data collection, Thomas added.

Flu also seems to be spiking nationally. The Centers for Disease Control and Prevention, which tracks flu across the United States, has also noted widespread flu activity increasing in 36 states, including Washington, Oregon, Idaho and California.

“The number of states reporting widespread flu activity jumped from 23 to 36, the proportion of samples testing positive for influenza at clinical laboratories went from 14 percent to 22.4 percent, and the percentage of people seeking outpatient care for influenza-like illness (ILI) increased from 3.5 percent to 5 percent over last week’s report,” the CDC’s Dec. 29 issue of FluView noted.

Nationally, since the beginning of October, 2,485 laboratory-confirmed flu-associated hospitalizations have been reported through the Influenza Hospitalization Network, which translates to a rate of about 8.7 hospitalizations per 100,000 people in the United States. The highest rates of hospitalization are among people age 65 and older, followed by those ages 50-64 and then by children under age 5, according to the CDC.

Flu season generally runs over three months somewhere between October and April, often starting in late December and ending in March. But for the past two years, the season has started a little early in November for Oregonians, Thomas said.

The state doesn’t track flu cases by region, but anecdotally, Thomas said she has seen what look like a few outbreak spikes in certain parts of the state.

“We don’t have much ability to track by regions, but right now it seems that Portland metro and the north coast are being hit the hardest,” Thomas said.

Heather Kaisner, Health Information Officer for Deschutes County Health Services, said Central Oregon is also seeing spikes.

“We are still collecting data for these past holiday weeks, however we are seeing an increase in flu, and flu is now widespread, similar to the rest of Oregon,” Kaisner said. “Flu tends to peak here around mid-January to early February, so while it has hit a bit earlier this year, we can’t say if we have peaked yet.”

Vaccine Issues

The problem with this year’s vaccine is that it matches some of the strains circulating, but doesn’t cover a new strain that’s causing problems.  

The H1N1 strain, which is older and makes up about three quarters of Oregon’s cases, is covered by the shot.

“The majority of what we’re seeing is the H1N1 strain - so the vaccine should be effective,” Thomas said.

The shot’s coverage of the mutated strain, H3N2, is far less effective though, and the flu shot won’t do much to prevent it, Thomas said.

“The H3N2 part of the vaccine hasn’t been effective, but the other two it covers are reasonably effective,” Thomas said.

The reason the shots don’t cover the new H3N2 strain is because it takes about six months to create and prepare each year’s set of vaccines. The newer strain wasn’t on the radar when this year’s shots were made six months ago.

To prevent against that strain, Thomas has more traditional recommendations: Wash your hands often, carry around hand sanitizer when you go out in public, don’t go into work if you’re sick and keep the kids home if they’re sick, too.

Also, if you haven’t yet - go get that flu shot, Thomas advised.

“You should get a shot,” she said. “I admit it’s not the best vaccine, but it’s safe. And we know H1N1 and the B-type strain the shot covers are circulating in Oregon.”

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