MITCHELL — South Dakota saw a flu season that was stronger than normal this year.

According to a recent report issued by the South Dakota Department of Health, the 2023-24 flu season is the worst in the past five years. The state has set five-year highs for the number of confirmed flu cases along with the most hospitalizations and deaths since 2018-19.

This flu season has included 19,911 confirmed cases. Davison County accounts for 529 of that total. The 831 hospitalizations statewide were the most since 2017-18 when there were 878 hospitalizations. The number of deaths was also the highest at 44, one more than 2018-19 when there were 43 deaths.

Those between the ages of 25 and 49 are the most likely to catch the flu, followed by younger people ages 5 to 24. The highest affected age group this season however was those between the ages of 5 to 24.

While numbers were higher than they have been in previous seasons, the data does not represent the severity of illness, according to State Epidemiologist Dr. Joshua Clayton. Clayton said the severity of the illness was similar to influenza seasons prior to the Covid-19 pandemic.

Though it is tough to pinpoint any single reason for this season’s bustling flu activity, medical professionals shed light on what they saw and why this flu season is setting records.

Dr. Darren Manthey, an emergency medicine physician with Avera Medical Group in Mitchell, agreed that flu activity seemed widespread this year.

“We had high rates of emergency department visits and outpatient visits,” Manthey said. “I would say it was a moderately severe season.”

Manthey also says the season ran later this year. Flu season typically peaks in the first week of February in South Dakota. However, the DOH stated the peak for the 2023-24 flu season wasn’t until the second week of March.

Manthey suggests that one of the reasons the flu hit the state harder this year is because fewer people chose to get their flu shots this year.

“The vaccination rate is slightly down this year,” Manthey said. “Lower vaccination rates mean more people aren’t protected and there are greater opportunities for the virus to spread.”

The downward trend in Influenza immunization has Avera Vice President of Clinical Quality Dr. David Basel concerned.

“The lower ‘herd immunity’ will likely lead to increased numbers and severity of the disease especially in the very young, the very old and the immunosuppressed,” Basel said.

While those getting the flu shot were down this year, according to Megan Jensen, a spokesperson for Sanford Health. System officials for Sanford said the flu shot this year was very protective against the influenza strains that were in existence this season.

Vaccine makers have to make educated guesses as they create flu shots well in advance of the respiratory virus season. Sometimes, the guesses are only so-so. But the ingredients in this year’s vaccine appeared to be right on target.

“The influenza and Covid vaccines were extremely effective, lowering the number of severe cases and hospitalizations,” Jensen said. “Vaccines continue to be the best protection against respiratory illnesses.”

Clayton also attributes the higher number to improvements in testing and reporting. There have been improvements in lab testing, so more clinics were able to do confirmatory influenza testing in clinic rather than having to send specimens to outside laboratories.

There have also been advancements in electronic laboratory reporting that have resulted in more timely and more accurate reporting that is automatic and not submitter based, according to Clayton.

Manthey points out that people often misuse the term flu. Influenza is different than having what’s often called the stomach flu. Sometimes people mistake symptoms of the stomach flu for the viral infection commonly called “flu.” But they’re not the same.

“Lots of people talk about getting the stomach flu, so they’ll get nausea, vomiting and diarrhea. They will say they have the flu,” Manthey said. “It’s important to recognize that influenza is a different disease.”

The flu, or influenza, comes with symptoms like fever, congestion, muscle aches and fatigue.

While the severity of influenza affecting people was not abnormal, some people report feeling sick or longer or struggling to recover from seasonal illnesses.

“The Influenza A I had was terrible,” said Karli Kiner, of Mitchell. “I had it three weeks ago and still have a lingering cough."

While people seem to be feeling a lot more rotten than usual, the good news it's probably not Covid or even Covid-related. While there are some theories out there that say immune changes may play a role in those with long-Covid syndrome, the linkage remains unclear at this time.

Basel said while there have been some studies suggesting that those who had severe (hospitalized) Covid have detectable changes in the immune system for many months, there is no clear evidence of immune changes in a more generalized population that had milder cases.

“We are still learning about what, if any, effect Covid will have on long-term immunity,” Basel said.

A small study done last year by the National Institute of Allergy and Infectious Disease found that people who recovered from severe Covid infections had long-lasting changes to their immune system for up to one year. It found stem cells from people with severe Covid produced more white blood cells which then produced more inflammatory signals in the body.

That study was done with cells in a laboratory Petri dish. Experts don’t really know what it all means clinically in a human body.

“There’s no evidence to support that Covid has damaged immune systems,” Manthey said.

Manthey suggests people might just be more aware of how we feel.

“A logical explanation as to why people seem more susceptible to illness than ever before is because we went through a respiratory virus pandemic and we are now more attuned to looking for illness than we were before the pandemic,” Manthey said.