Though the flu season started slow in October, influenza activity has been increasing since November, according to a report released Dec. 29 from the CDC.
Here are six things to know about the 2016-17 flu season so far.
1. Influenza A viruses have been the predominant strain, H3N2 in particular.
2. As of Dec. 19, all viruses tested have been sensitive to the antiviral drugs oseltamivir, zanamivir and peramivir.
3. Flu has hit some states and cities harder than others. Oklahoma and Puerto Rico have seen high volumes of outpatient visits influenza-like illness, and Arizona, Georgia and New York City have seen a moderate volume of such visits.
4. As for the geographic spread of the flu virus this season, only Puerto Rico reported widespread activity for the week ending Dec. 17. Guam, the U.S. Virgin Islands and 13 states (Alabama, Alaska, Connecticut, Massachusetts, New Hampshire, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, South Carolina, Virginia and Washington) have reported regional flu activity.
5. So far this flu season, the percentage of deaths attributable to pneumonia and influenza has remained below the epidemic threshold.
6. No flu-associated pediatric deaths have been reported for the 2016-17 season as of Dec. 17.
Note: The headline of this article was updated Jan. 5 to correct spelling.