Doctors say springtime influenza B viruses arriving earlier than expected

The flu season is moving toward its peak, with a twist that has researchers scratching their heads.

The influenza B/Victoria viruses that usually appear in early spring are currently the dominant strains across the country. Some experts say the B viruses impact children more than adults and are often mistakenly viewed as less serious than A (H1N1) viruses.

“Everyone is flummoxed by the B viruses causing large outbreaks,” said Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases and an infectious disease specialist at Vanderbilt University Medical Center. “Usually, they keep going when the A viruses recede.

“Kids are a great engine for the spread of influenza, and B seems to like kids,” he added. “So I would emphasize even more that everyone six months and older, including children, should get vaccinated. It’s not too late.”

The U.S. Centers for Disease Control and Prevention estimates there have been 6.4 million flu illnesses, 55,000 hospitalizations and 2,900 deaths from the flu this season across the country. Flu season generally peaks in January and February but can often last into the spring, officials said.

Cases in New York State jumped 74% last week, bringing the total confirmed cases to 22,763 this season, along with 3,592 flu-related hospitalizations, prompting the state Health Department to issue a health advisory on Friday. The number of weekly hospitalizations increased 119%, the agency reported. 

Brad Hutton, deputy commissioner for public health with the state's health department, said the current flu vaccine provides effective prevention against both flu strains.

"People can get stricken with Flu A and then get Flu B later in the season," Hutton said. "That's all the more reason to get vaccinated."

Dr. Shannon Henning, medical director of PM Pediatrics in Massapequa Park, said the urgent care center is seeing more young patients with flu-like symptoms than last year.

“It hit hard, it hit quick and it hit a little earlier than expected,” she said of the flu season. “We are seeing more families wanting everybody tested even if only one person has fever … we are definitely seeing more Flu B than Flu A.”

Henning said parents with children who have chronic health conditions such as asthma and diabetes are more vigilant in making sure they are vaccinated than others.

“We have seen a lot of kids not vaccinated,” she said. “Every child should get a vaccine.”

CDC spokeswoman Kristen Nordlund said there is a misconception that influenza B viruses are associated with milder disease than Flu A viruses.

“So far this season, influenza B virus infections account for almost half of hospitalizations reported through [the] CDC’s flu hospitalization surveillance network and 18 of the 27 reported pediatric flu deaths,” Nordlund wrote to Newsday in an email. “So the vaccine, or early antiviral protection if you are sick, are the best ways to protect yourself.”

Schaffner said the current vaccine appears to match the flu strains that are circulating.

The last time B strains dominated the flu season was in 1992-93, Nordlund said. But it’s too soon to know whether that will be the case this season, experts warn. The A strains could bounce back and take over.

“The way [strains] are tracked is helpful in understanding the epidemiology of the flu, but from a practical standpoint, it doesn’t change how we care for individual patients,” said Dr. David Hirschwerk, an infectious disease specialist at Northwell Health.

“It’s interesting that we have a higher number of flu cases overall and also more Flu B cases at this timepoint, but that significance is uncertain,” said Hirschwerk, who is also vice chair in the department of medicine at North Shore University Hospital in Manhasset and LIJ Medical center. It could mean the season peaks early instead of signaling an increase in flu cases, but it's impossible to know for sure, he said.

Medical experts said the best advice to avoid the flu is still the basics: Wash your hands, avoid contact with people who are sick, and, mostly importantly, get a flu shot.

“With all the travel, hugging and kissing that goes on during the holiday season, people give the gift of the flu virus,” Schaffner said. “We will be seeing the consequences of that in the coming weeks.”