While the number of reported flu cases is down nationwide, a second wave of the illness is starting to spread.
According to the CDC's weekly surveillance report ending March 17, the number of "Influenza B" cases are now being reported more often than the A-strain. During that week, nearly 58 percent of all lab-confirmed cases were caused by the B-strain, according to the report.
Overall, "Influenza A" cases have dominated the flu season up until this point, the CDC noted.
CDC spokesperson Kristen Nordlund explained to CNN that parents with younger children should continue their vigilance.
"We know that illness associated with influenza B can be just as severe as illness associated with influenza A," Nordlund told CNN. "We also know that influenza B tends to be more severe for younger children."
She added that this second wave of B-cases is not unexpected, but it's not yet known what this flu wave will look like.
Since October, 26,694 people have been hospitalized with flu-related symptoms, with nearly 78 percent of those hospitalizations related to the influenza A virus, according to the CDC.
