Influenza-related deaths in Oklahoma have reached 85 since Sept. 28, 2014, a record since the Oklahoma State Department of Health began tracking flu statistics in 2009. The previous high number was during the 2013-14 flu season, with 72 deaths. Most of the deaths, 63, occurred in people aged 65 or older. North Carolina has had a total of 164 deaths this season.

Flu has also claimed a fifth child in Minnesota, even as that state’s epidemic is fading. The season was both harsh and widespread. Although deaths are most common among the infirm and the elderly, seasonal flu kills thousands of American each year.

More than 1,700 people have been hospitalized with flu-like symptoms since Sept. 28. Seventy-six of those hospitalizations have occurred within the past week. Several factors are contributing to this season’s high death toll, according to Health Department officials. One reason is that this year’s flu vaccine is only about 23 percent effective, which falls far short of the usual 50 to 60 percent effectiveness. In addition, this seasons flu strain is predominantly the aggressive H3N2 virus, a strain which experts say is associated with more serious illness. The strain has also mutated, further eroding the vaccine’s effectiveness.

Karen Martin, an epidemiologist with the Minnesota Health department, says that it is not too late to get a flu shot. She says that flu cases can be expected to linger for a couple more months.