Second wave of flu season hits U.S.

April 6 (UPI) -- The winter season ended last month but that doesn't mean the danger of getting the flu is over, even though it is springtime.

Rather than getting a strain of Influenza A, you have a greater chance of getting Influenza B. They carry roughly the same level of severity, having a similar cough, runny or stuffy nose, itchy or watery eyes, sore throat, fatigue and low fever.

On Friday, the Centers for Disease Control and Prevention reported the 13th week of the flu season, through last Saturday, had reduced cases of influenza in the United States. The flu season peaked 10 weeks ago.

"Various influenza years or seasons can have different 'lengths' based on overall activity of influenza and, say, when the heightened activity starts," Dr. Dana Hawkinson, an expert in infectious diseases at University of Kansas Health System, told UPI. "This year does seem to be a bit more intense and seemed to have increased influenza activity earlier than recent past years."

Although influenza A(H3) viruses have predominated this season, the influenza B viruses have increased.

"The different 'wave' that is discussed is influenza type B," Hawkinson said. "More than 70 percent of this year's influenza infections during this flu season has been type A. Now there is slight increase of type B infection."

In the latest results, the CDC said the breakdown was 39.6 percent for Influenza A and 60.3 percent for Influenza B. Among 21,823 specimens tested, 15.4 percent were positive.

"The percentage of respiratory specimens testing positive for influenza in clinical laboratories remains elevated," the CDC said in the report.

The highest levels of flu were reported in Alaska and Virginia. Eight states experienced moderate activity: Arizona, Kentucky, Michigan, Nebraska, North Carolina, South Carolina, South Dakota, and Wyoming. Twenty-eight states reported minimal activity.

A total of 142 pediatric deaths were reported.

"The dominant strains every year are one of the A strains. They create the big epidemics," Dr. William Schaffner, an infectious disease expert at Vanderbilt University, told HealthLine. "Now, behind the scenes as it were, there are influenza B strains that are circulating at the same time. They cause illness that is just as severe, but the B strains, for biological reasons that we don't understand, don't create big epidemics, but they smolder along."

The good news is that Influenza B can be more easily and effectively treated than Influenza A with the flu vaccine, as well as antivirals, including Oseltamivir, known commonly as Tamiflu.

The flu vaccine had a 25 percent effectiveness rate against H3N2 this year, but 42 percent against influenza B with Yamagata lineage.

But bad news remains: You can still get sick from influenza B even if you've already been hit with an A strain.

"It is recommended to continue to give influenza vaccine until your institution runs out or they expire," Hawkinson said. "We are currently still giving vaccine. It certainly could provide benefit, with very little risk."