Centers for Disease Control and Prevention influenza experts are concerned that the United States could be at risk for a severe flu season this year, Director Dr. Rochelle Walensky warned Wednesday.That’s because the U.S. population may now have reduced immunity against influenza after seasonal flu cases reached an all-time low last year when large parts of the nation were shut down, Walensky told reporters during a White House press briefing.CNBC, Read More.