But unlike the swine flu outbreak, there was no evidence of a new virus that prompted the wave of hospitalizations this season.
And health officials say it’s hard to pinpoint exactly why the flu season was so brutal, hospitalizing 5,239 Ohio residents from September last year through May 18, the state health department’s final flu-activity report showed.
The Clark County Combined Health District reported 57 hospitalizations this past season, more than the 43 total over the two prior seasons. In Champaign County, 12 hospitalizations resulted last season, well above the one case from each of the previous two years.
“There are lots of factors that come into play, and they’re all independent of one another,” said Dr. Thomas Herchline, medical director for Public Health – Dayton & Montgomery County. “There are years where there are more cases of people who get influenza but don’t get that sick. And there are years were there are fewer cases, but more people go to the hospital.”
In general, the area followed state and national trends in which the flu season began about a month earlier than normal and hospitalizations began to rise in mid-December before peaking early this year.
Many of those hospitalized were 65 or older, also reflecting the nationwide trend in which seniors accounted for more than half of reported cases through the end of March, according to the Centers for Disease Control and Prevention.
Hospitalization rates among seniors rose from 17 per 100,000 people for the week ending Dec. 15, 2012 to 182 per 100,000 for the week ended March 23, according to the CDC, which calculates hospitalization rates based on surveys from select states, including Ohio.
Brian Fowler, an epidemiologist with the state health department, said seniors and children are more susceptible to the flu because of their naturally weakened immune systems, but people over 65 are generally more likely to be hospitalized with influenza.
“During H1N1, more hospitalizations were in children than usual,” Fowler said. “The 2012-2013 season saw a return to higher hospitalizations in the elderly and relatively few in children.”
Fowler said it’s critically important that children and seniors get vaccinated against influenza because research shows the flu vaccine is highly effective in preventing severe illness and hospitalizations.
Still, no weapon against the flu is 100 percent effective, said Duane Stansbury, Health Commissioner at the Warren County Combined Health District, noting the flu vaccine used this season was less than 60 percent effective in healthy adults, according to the CDC.
“A number of our cases were not directly related to a specific strain that was covered by the vaccine,” said Stansbury, whose health department recorded 99 flu-related hospitalizations this past season, up from 11 in the previous season.
In addition, “It’s difficult to know if we had people who were not being vaccinated and getting sick or if we had people who were getting vaccinated and still getting sick and being hospitalized,” he said.
Health officials say hospitalizations are the best measure for the intensity and severity of the flu seasons in Ohio, because the state only tracks infant deaths related to the flu.
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