According to the Centers for Disease Control (CDC), millions in America are suffering from the influenza virus this season. In fact, experts are calling it an “unusually active and dangerous flu season.”

The Hill reports that according to health experts, the epidemic is a result of several distinct strains that “are likely to kill tens of thousands” in the U.S.

The flu is widespread in every state with the exception of Hawaii, and in 40 states as well as Puerto Rico, flu rates are at high levels, the CDC reports.

The current rates are comparable to the last two bad flu seasons, the most recent of which took place in 2014-2015. At that time, an estimated 34 million Americans contracted the flu, with 56,000 fatalities occurring as a result. The other especially bad flu season occurred in 2009 and sent millions of infected Americans to the hospital.

“For the past three weeks, the entire country has been experiencing lots of flu all at the same time,” said Dan Jernigan, director of the CDC’s National Center for Immunization and Respiratory Diseases’ Influenza Division.

The virus is among the greatest concerns of public health officials.

“When we think about a microbe and how bad it is, we think about two things: How easily it spreads, and how nasty it is, its virulence,” said Tom Frieden, a former CDC director. “Flu is that rare bird that potentially could be both easily spreadable and have a relatively high lethality.”