The CDC is urging U.S. residents to get the influenza vaccine as soon as possible. With flu cases on the rise, health officials around the country are scrambling to cope with the increasing number of patients. Reuters

Flu season is upon us, and according to the latest reports, health officials are seeing a surge in new cases. Nearly half of the U.S. reports widespread influenza activity, with parts of the southern U.S. experiencing the highest rates of infection. According to the Centers for Disease Control and Prevention, the majority of it is attributed to the H1N1 virus, also known as swine flu, which caused a worldwide panic in 2009.

"We are seeing a big uptick in disease in the past couple of weeks,” Dr. Joe Bresee, chief of Epidemiology and Prevention in the CDC's Influenza Division, said in a statement, according to CBS News. “The virus is all around the United States right now.”

Flu season peaks in the U.S. between October and March. Seasonal flu is a contagious respiratory illness caused by a number of flu viruses, including H1N1, which killed 284,000 people worldwide in 2009 and 2010.

According to flu.gov, between 5 percent and 20 percent of people living in the U.S. get the flu each year. Symptoms can be mild or severe and include fever, a cough, sore throat, weakness, headache and aches and pains in the joints and muscles around the eyes. Serious complications include bacterial pneumonia, ear or sinus infections, dehydration or worsening of chronic health conditions. The virus causes thousands of deaths in the country every year.

The CDC has documented 1,583 laboratory-confirmed cases of the flu since Oct. 1, 2013. The information came from data collected from 13 states representing about 8.5 percent of the total U.S. population.

“We’re seeing pretty substantial increases in activity, but they’re not unexpected,” Dr. Michael Jhung, a medical officer in the flu division of the Centers for Disease Control and Prevention, told NBC News. “We see pockets of high activity in several states and pockets of low activity in others, but we expect every state will get hit.”

The CDC reports that young and middle-aged adults are especially affected this season. “If pH1N1 virus continues to circulate widely, illness that disproportionately affects young and middle-aged adults may occur,” the CDC noted in a statement. While the CDC does not track adult deaths caused by the virus, there have already been dozens of reports of deaths.

“The spectrum of illness observed thus far in the 2013-14 season has ranged from mild to severe and is consistent with that of other influenza seasons,” the CDC said. “While CDC has not detected any significant changes in pH1N1 viruses that would suggest increased virulence or transmissibility, the agency is continuing to monitor for antigenic and genetic changes in circulating viruses, as well as watching morbidity and mortality surveillance systems that might indicate increased severity from pH1N1 virus infection.”

Texas is one of the states to have been hit the hardest this flu season. According to Reuters, at least 25 people have died from the flu this season. An “influenza health alert” was issued in December by the Texas Department of State Health Services, who advised doctors to vaccinate patients against the flu even if their flu tests come back negative.

There is currently no vaccine for the current outbreak of H1N1, but getting an annual flu shot is a first line of defense against the virus.