Influenza B virus seen for 1st time in 27 years

Rare early emergence puts kids at higher risk

As an infectious disease specialist for the better part of four decades, Bernhard “Bud’’ Wiedermann has deep expertise on a range of illnesses, from malaria to Lyme disease to recurrent fevers.

This year’s flu season has thrown him a curveball, though it is thankfully one he can adjust to: a predominant influenza B virus for the first time in 27 years.

When outbreaks of the flu began a few weeks earlier than usual in the fall, Wiedermann and his colleagues at Children’s National Hospital in Washington, D.C., noticed a leading cause was a virus that doesn’t typically emerge until the end of the season and is more likely to affect children.

“All of us here when we started seeing that coming through, not only from the

CDC data but from our own testing, we were like, ‘Wow, what’s going on? This is very strange,’’’ Wiedermann said.

Though initial signs pointed to the powerful A(H3N2) strain as the biggest concern this season, the Centers for Disease Control and Prevention said most of the illnesses have been caused by B/Victoria viruses, followed by A(H1N1) viruses.

The effect has been particularly harsh in Louisiana, where a New Orleans pediatric care facility reported 1,268 confirmed B virus infections in children from July 31 to Nov. 21, leading to 23 hospitalizations.

Nationwide, the CDC said flu activity is high and will remain that way for weeks, although the level of severity appears lesser than in the past. For the season, the agency has tallied at least 9.7 million cases of the flu, 87,000 hospitalizations and 4,800 deaths.

More than 68% of the positive results from tests in clinical labs were linked to the influenza B virus, which had not been predominant since the 1992-93 season. Those infections have accounted for nearly half the hospitalizations reported to the CDC.

The symptoms are the same regardless of the virus: fever in many cases, as well as a sore throat, cough, body aches, fatigue, runny or stuffy nose and headaches. But one significant difference is this year’s dominant viruses figure to impact children and young adults more than older folks.

That makes it imperative for parents to make sure their kids get a flu shot, even at this point in the season, the CDC and Wiedermann said. In past years, about 75% of the children who died from the flu weren’t vaccinated.