the flu started spreading earlier than usual in some parts of the country, raising concerns that cases could soon surge as millions of Americans travel and gather for Thanksgiving and other upcoming holidays.
The warning signs come as a form of the virus called H3N2 subclade K has caused massive outbreaks in Canada and the UK.
Dr. Cameron Wolfe, an infectious disease specialist at Duke University School of Medicine in Durham, North Carolina, said he has seen a sharp increase in flu cases over the past few weeks.
“Usually at this point I might see one or two cases a week,” Wolfe said. “We’re getting two, three, four a day at the moment.”
Alicia Budd, head of the Centers for Disease Control and Prevention's internal influenza surveillance group, said, “We certainly expect to see an increase in influenza activity over the next few weeks.”
Most of the flu circulating in the U.S. this season is the H3N2 strain, according to the CDC. H3N2 flu tends to cause more hospitalizations and deaths among older adults.
The early rise in cases could pose unique risks for this age group, Wolfe said.
“If you're looking at a really early flu season, you run the risk that some nursing homes may not have completed their vaccine rollout. The hospital may not have fully vaccinated its staff,” Wolf said. “The community as a whole may not be as protected as it would have been if, for example, the virus had emerged in January.”
Although influenza activity is generally considered low, Latest CDC Flu Report shows that the number of cases is increasing. The agency estimates that at least 650,000 people have gotten sick with the flu this season. About 7,400 people were hospitalized and 300 died, according to the report.
Budd said the increase in illnesses and emergency room visits is concentrated in children.
Last year, 280 children in the US died from the flu. It was Deadliest flu season ever recorded for childrenexcluding the 2009-10 H1N1 pandemic.
There have been no reported deaths among children this season. Still, the early rise in flu activity is alarming to doctors who watched the virus spread through schools, day care centers and, consequently, hospitals last winter.
“It's like the calm before the storm,” said Dr. Buddy Creech, a pediatric infectious disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee. “We could have a tough flu year.”
The H3N2 strain is known for its ability to mutate easily. The K-form subclade of the strain emerged in the summer with several mutations. This became known after the composition of this season's flu shots was determined.
Budd of the Centers for Disease Control and Prevention (CDC) said the agency is studying how well the flu vaccine matches this latest flu strain. However, she urged people to take a photo.
Most of the flu circulating this year is an A strain called H3N2, according to the CDC. H3N2 is known for its ability to mutate easily.
This particular H3N2 variant, called subclade K, emerged over the summer after the composition of this year's flu shots was determined. It's already caused massive outbreaks in Canada and UK
The CDC's Budd said the agency is studying how well the flu vaccine matches this latest flu strain. However, she urged people to take a photo.
“Even in years when the strain in the vaccine may not be as similar to the strains we see circulating, we know that the vaccine can help prevent the severity of the disease,” Budd said.
Doctors across the United States are closely monitoring the rise in flu cases.
“Is he turning our antenna up a little more? Yes,” said Dr. Daniel Varga, chief medical officer at Hackensack Meridian Health in New Jersey. “This makes us even more vigilant about the traditional monitoring we do in the field.”
Dr. Melanie Kitagawa, medical director of the pediatric intensive care unit at Texas Children's Hospital in Houston, said it's not too late to get a flu shot.
“The more people we can vaccinate before the flu season starts, the better it will be,” Kitagawa said.
