The flu is infecting an unusually high amount of children this early in the season because influenza B is the predominant strain — a trend that hasn't been seen for more than a quarter century, reports The Wall Street Journal.
"We've seen something this year that we haven't seen in probably 27 years, which is a noticeable increase in the number of influenza B infections early in the season," Andi Shane, MD, chief of pediatric infectious diseases at Emory University School of Medicine and Children's Healthcare of Atlanta, told WSJ.
The strain causes more severe illness in children because they have less exposure to the virus and, therefore, fewer antibodies.
This season, 53 percent of positive flu specimens tested in public health laboratories have involved children and adults under 25, according to the CDC's most recent FluView update. The agency has also confirmed 68 pediatric flu deaths this season, 45 of which involved influenza B.
"At this time, the number of cases reported with complete vaccination status information is too low to calculate exact percentages," an agency spokesperson told Becker's via email. "Historically, around 80 percent of flu-associated pediatric deaths have occurred among children who were unvaccinated."
The CDC said it's too early to say whether this season's flu shot is a good match for influenza B in its weekly flu update. The agency plans to publish data on vaccine efficacy later this month.