As Colorado slogs through an especially bad flu season — the result, experts say, of a nasty strain of influenza that vaccines have trouble targeting — a state health official said there may be some good news on the horizon.
The latest data suggests that the flu season is far from over but may be close to peaking in Colorado, said Dr. Rachel Herlihy, the state epidemiologist.
“It does look perhaps like we could peak sometime this month,” she said.
That would be a welcome milestone for a season where three times as many people have been hospitalized for the flu as normal. Through last week, 1,582 people had been hospitalized with the flu in Colorado. The state does not track total flu deaths in real time, but Herlihy said no children have died from the flu so far this season, a period that begins in October and run through spring.
Flu generally kills a few dozen people in Colorado each year. In 2016, the most recent year for which numbers are available, 54 people died of influenza, according to state data.
Colorado is one of 46 states reporting widespread flu activity, but, compared with much of the rest of the country, Colorado’s season isn’t as severe. In its most recent report, the federal Centers for Disease Control and Prevention labeled Colorado’s activity as “moderate,” while the activity in 26 other states was labeled as high.
But what is driving this terrible flu season is the same everywhere.
The predominant strain of flu that doctors are seeing, both in Colorado and across the country, is a type of Influenza A called H3N2. The strain is often associated with a higher number of hospitalizations, especially for older adults. Colorado’s worst flu season on record, in 2014-15, was an H3N2 year and saw 3,397 hospitalizations.
It can also be especially tricky to vaccinate against.
Modern flu vaccines are designed to provide protections against multiple strains of flu, lowering the risk that the vaccine will whiff completely. But H3N2 can mutate during the vaccine production process, meaning that the virus in the shot can be slightly different than the virus on the street. That is what happened last year, according to one study, when the CDC found that the flu vaccine, overall, was 39 percent effective — but the H3N2 component of the vaccine was only 32 percent effective.
This year’s vaccine could be even more troubled. Preliminary estimates from Australia — often an early-warning system for the North American flu season — put the effectiveness of that country’s vaccine for H3N2 during the most recent season at a meager 10 percent.
Dr. Ryan Oyer, an infectious-disease physician with Kaiser Permanente Colorado, said the effectiveness numbers for this season’s vaccine in America won’t be known for several months. But, he said, people should still get a flu shot.
“The influenza vaccine is not perfect, but it’s the best we’ve got,” he said. “It’s certainly the best strategy we have from a public-health perspective.”
Even though doctors recommend getting a flu shot in the fall, Oyer said it’s not too late to get one now. He said frequent hand-washing, covering your face when you sneeze or cough and wearing a mask when you are sick and have to go out into public will all help limit the spread of flu.
And there’s one other thing. When you get sick, stay home from work until you’ve gone 24 hours without a fever.
“Your public health officials will say thank you for doing that,” Oyer said.
