The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults less than 25 years, while A viruses are the most commonly reported influenza viruses among persons 25 years and older. In the most recent weeks, influenza A viruses are the most commonly reported influenza viruses in all but the school aged children and young adults (5-24 years old). " -- https://www.cdc.gov/flu/weekly/index.htm#ILIMap