The emergence of an unlikely strain of influenza has sickened and killed an unusually high number of young people this flu season, according to doctors and public health experts.
Most people hospitalized with the flu in Los Angeles County this season have been under 45, said Dr. Jeffrey Gunzenhauser, the county public health department’s chief medical officer. That age group has also made up an unexpectedly large portion of the county’s flu deaths, he said.
“I don’t really understand this,” Gunzenhauser said in an interview. “It’s very unusual.”
Influenza B, the most common strain of flu this season, tends to make more young people sick than Influenza A, which is typically circulating during flu season, experts say. In the United States, it has been nearly 30 years since Influenza B was the most common flu virus infecting people.
The silver lining, experts say, is that it may make this year’s flu season mild overall. Influenza B tends to cause a less severe illness than Influenza A, and young people tend to fare better when they do catch the flu than older people.
Overall, the flu remains most deadly for the elderly. In California, 105 people have died of the flu so far this season, more than half of whom were over 65 years old, according to state data released Friday.
Hospitals across Southern California reported that their ERs began to fill up around the holidays with patients complaining of fevers, headaches, sore throats and other flu symptoms. That spike in patients has continued into January.
UCLA emergency rooms have been busy with people of all ages testing positive for the flu, said ER physician Dr. Lisa Dabby. But people under 24 are showing up at the ER much more often than other age groups, according to a university memo.
“Influenza B is predominating this season,” Dabby said.
It’s unclear why Influenza B does not affect older people as much. Some experts believe that since Influenza B doesn’t mutate as much as other flu strains, older people have immunity to it because they have probably caught it before.
At Children’s Hospital Los Angeles, doctors have been treating not just routine flu cases, but dangerous illnesses linked to the flu, including pneumonia or swelling of the brain, said Dr. Pia Pannaraj, pediatric infectious diseases specialist. These patients who need to be admitted to the hospital often have Influenza B, she said.
“We’ve definitely seen quite a rise in children presenting with flu,” Pannaraj said.
Statewide, five children have died of the flu, according to state data. Nationwide, 39 children have died of the flu this season, according to federal data released Friday.
Though there was a spike in flu cases around the holidays, it’s impossible to know whether the flu season has peaked. The flu season is considered to run from October through May and typically peaks in January or February.
Officials recommend the flu shot for anyone over 6 months old. Multiple viruses pop up during flu season, so people who have already gotten sick could still benefit from the protection of a flu shot.
“Just because we are sort of deep into flu season doesn’t mean people can’t still get the flu shot,” said Dr. Nicholas Testa, chief physician executive overseeing six Dignity Health hospitals in Southern California. “Even if it peaks this week, next week or in two weeks, that doesn’t mean it’s over.”