(Nexstar) – Influenza is spreading widely throughout the United States – and influenza A is primarily responsible. Of all flu tests reported to the Centers for Disease Control and Prevention since the start of the flu season last fall, around 97% have tested positive for flu A.
Influenza A is further divided into subtypes. According to the CDC, you may have heard of H1N1 or H3N2.
“Influenza A usually has worsening symptoms than influenza B, and patients are more likely to be hospitalized with influenza A compared to influenza A,” says Donald, an infectious disease expert at Cleveland Clinic. Dr. Donford said.
However, Dr. Amesh Adalja, an infectious disease expert at the Johns Hopkins Center for Health Security Center, warned that influenza B is also dangerous. “Influenza B can also become severe, but influenza A is the dominant version of influenza currently infected with the flu.”
Both types spread in the same way, causing similar symptoms, and are most dangerous for babies and elderly people. The flu vaccine is formulated to protect against both types.
Flu A domination at this point in the flu season is expected. Influenza A is common in the early winter flu season, but influenza B appears to occur around early spring.
Dunford expects the shift to take place in late February or early March this year.
There are two other types of influenza. There are C and D-, but there's nothing too much to worry about. Influenza C usually causes mild illness and does not cause a widespread outbreak, according to the CDC, influenza D mainly affects cattle.
