This year’s flu season could be a bad one, the U.S. Centers for Disease Control and Prevention (CDC) has warned.
Drawing on data showing that so far, the most common flu strains seen this year are also those responsible for the most deadly flu seasons of the decade, according to the CDC.
The CDC said the flu viruses most common this year are A H3N2 strains, which often cause more severe illnesses, hospitalizations and deaths than some other strains. In addition, about half of the viruses seen during the flu season to date have genetically mutated from the vaccine virus, significantly reducing the vaccine’s effectiveness.
“It’s too early to say for sure that this will be a severe flu season, but Americans should be prepared,” said Dr. Tom Frieden, CDC director.
“We can save lives with a three-pronged effort to fight the flu: vaccination, prompt treatment for people at high risk of complications, and preventive health measures — such as staying home when you’re sick — to reduce flu spread,” Frieden said.
Depending on the formulation, the agency said, flu vaccines protect against three or four different flu viruses. Even during a season when the vaccine is only partially protective against one flu virus, it can protect against the others that may become prevalent later in the season.
Flu viruses constantly change
Influenza viruses are constantly changing, according to the CDC. The mutated, or “drifted” H3N2 viruses, were first detected in very small numbers in late March 2014, after World Health Organization recommendations for the 2014-15 vaccine had been made.
A committee of experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered in time for the upcoming flu season. There is always the possibility that viruses will drift during that time.
Those at high risk
Those at high risk from influenza include children younger than 5 years (especially those younger than 2 years); adults 65 years and older; pregnant women; and people with certain chronic health conditions such as asthma, diabetes, heart or lung disease, and kidney disease.
CDC recommends that people at high risk check with their doctor or other healthcare professional promptly if they get flu symptoms. Flu symptoms can include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue.