The winter flu season is officially underway, marking the earliest start to the period of widespread sickness in more than 15 years.
According to the Associated Press, the last flu season to be in full swing this early was in 2003-2004. That flu season saw more than 48,000 deaths in the U.S., making it one of the deadliest flu seasons in decades, the AP reported.
The winter flu season in the United States can begin as early as October or November, according to the U.S. Centers for Disease Control and Prevention, and can end as late as May.
Health officials consider a flu season to be in full swing when a significant percentage of doctor’s office visits are due to flu-like illnesses for at least three weeks in a row, the AP reports.
The CDC estimates that there have already been at least 1.7 million flu illnesses, 16,000 flu hospitalizations and 910 flu deaths between October 1 and November 30.
An early start to the flu season could signify it's going to be a bad one, but health experts told the AP it could be too soon to tell how the 2019-2020 flu season will go.
According to the CDC, Puerto Rico and 12 states are already experiencing high levels of flu activity, with the South being affected particularly hard. Alabama, California, Connecticut, Georgia, Indiana, Louisiana, Massachusetts, Mississippi, Nevada, New Mexico, New York, Pennsylvania, South Carolina, Tennessee, Texas, and Virginia are all experiencing high influenza-like illness activity, the CDC says.
What's also surprising, so far, for this flu season is the type of virus that is causing the early start. The CDC says flu activity is being caused mostly by influenza B/Victoria viruses, which is unusual for this time of year. This particular strain of viruses is hard on children and people younger than 50 years old.
"Nationally, influenza B/Victoria viruses are the most commonly reported influenza viruses among children age 0-4 years (46% of reported viruses) and 5-24 years (60% of reported viruses)," the CDC says.
The CDC says flu season is just getting started and elevated flu activity is expected to continue for weeks, so be sure to get your flu shot if you haven't yet.