Influenza activity increases in Iowa

Flu infection rates have been increasing in Iowa over the last few weeks, but they should start dropping again soon, according to Dustin Arnold, chief medical officer at UnityPoint Health — St. Luke’s Hospital.

“I think the flu probably peaked last week,” Arnold said. “It’ll still drift for a while, for the next maybe two weeks, and then it will start to decline.”

  Buy Photo

Flu rates spiked at the end of December, right after the holidays, but decreased for a couple weeks before starting to trend back upward, according to the most recent weekly Iowa Respiratory Virus Surveillance Report, which classifies influenza activity in the state as “very high.” The report tracks the percent of respiratory virus tests administered in labs across the state that came back positive for the flu, COVID-19 and RSV.

In the most recent report, which covers the week of Jan. 18-24 and was released Jan. 29, there was a 2.3 percent increase in positive flu tests across Iowa, with a total of 30.5 percent of tests coming back positive. COVID and RSV both had minor increases as well.

The report also includes data showing 119 schools across the state reported at least 10 percent illness during the week of Jan. 18-24. That total included five schools in Linn County, five in Johnson.

Dr. Matthew Fox, chief medical officer at Mercy Cedar Rapids, said the increase in activity is likely because of the cold, dry weather. More people have been spending time inside, without much air circulation because of freezing temperatures outside, which it makes it easier for viruses to spread.

  Buy Photo

Plus, Fox said, the cold weather can keep viruses alive on surfaces for longer, and the low humidity makes respiratory droplets lighter, meaning contagious breaths stay in the air longer. Dry air also can dry out mucus membranes, which help protect against illness.

“There are a lot of things that come together to create these spikes,” Fox said.

There’s one strain of influenza A — called h3n2 subclade K — that has been especially prevalent this year, Fox said, because it mutated after the flu vaccines for the 2025/2026 season were developed. That means the symptoms are slightly more severe than those from the other flu strains, even for people who are vaccinated.

“You still get protection from the vaccine, so I don’t want people to think it’s not worth getting your vaccine. It certainly is. It’s one of the most important things you can do is get the flu vaccine, but it’s not covered quite as well as it would be,” Fox said.

Influenza B also has been picking up over the past couple of weeks. Arnold said at UnityPoint Health — St. Luke’s Hospital the weekly case count for influenza B increased over the last three weeks from 11, to 24, to 35 cases.

Fox and Arnold encouraged people to do what they can to avoid spreading illness, including washing hands thoroughly, cleaning high-touch areas like doorknobs, and covering your nose and mouth when you cough or sneeze. People who are at higher risk for complications can wear a mask to decrease your chances of getting sick.

  Buy Photo

If you suspect you may have the flu, make sure to hydrate, stay home and reach out to your medical provider as quickly as possible, especially if you have other conditions, like asthma, lung disease, heart disease, or others, that make you high risk.

Fox said the typical recommendation for the flu is to stay isolated until at least 24 hours after fever is gone, but it’s possible to be contagious until up to five days after symptoms start improving. A person also can be contagious for 24 hours before starting to feel sick, so it’s wise to let people you’ve recently interacted with know that you have the flu.

“If you’re going to be around people, especially high-risk people, wearing a mask for up to five days after your symptoms improve can be helpful as well,” Fox said.

Comments: (319) 398-8328; emily.andersen@thegazette.com