Last year at this time, influenza season was so mild, we barely noticed.
But this year, flu season arrived about a month early and quickly built to the worst level in a decade.
Nationally, the number of states reporting high levels of patients with flu-like illness decreased last week. But it's too soon to say if the worst has passed.
As always, anyone experiencing flu-like symptoms should stay away from hospitals, nursing homes and other venues where they could infect others.
While we're in the thick of it, here are some things to remember:
It's not too late
You can still get a flu shot. It takes about two weeks after the vaccination to build up enough antibodies to effectively fight off the flu, but flu season often doesn't peak until late January or February.
"Last year everyone got their flu shots, but then the flu season was very mild," said Dr. Lisa Burke, a physician at Carolinas Medical Center's Arboretum Urgent Care. "People have gotten lackadaisical about their flu shots this year."
Federal health officials recommend flu vaccine for everyone 6 months of age and older. It is especially important for people who are at high risk of serious flu complications, including young children, pregnant women, people with chronic health conditions (such as asthma, diabetes or heart and lung disease), and people 65 years and older.
Vaccine still available
Despite some reports, there is no shortage of the flu vaccine this year.
"Some of our locations may experience intermittent, temporary shortages of flu vaccine, but we still have vaccine in stock and we resupply our pharmacies and clinics as quickly as possible," said Mike DeAngelis, a national spokesman for CVS.
Shot or spray?
Choose from the common injectable vaccine and the nasal spray vaccine called FluMist.
Contrary to popular myth, health officials say the injectable vaccine cannot cause flu. That's because it's made from a killed virus. "It can make you a little achy, but it cannot give you the flu," Burke said.
FluMist, on the other hand, is made with a small amount of live attenuated virus, which does not cause flu but could cause a mild reaction, including lethargy, officials said. That's why it is recommended only for healthy people age 50 and under.
Some people who have been vaccinated still get the flu. But when that happens, doctors say symptoms are usually less severe and their duration is usually shorter.
"Probably about 10 percent of the people I'm seeing (with flu symptoms) have had the vaccine," Burke said. But "their symptoms have not been as bad."
This year's vaccine offers a "moderate" level of protection at 62 percent, according to the Centers for Disease Control and Prevention.
"That means if you got vaccinated you were about 60 percent less likely to get influenza," CDC Director Thomas Frieden said last week. "Influenza vaccine is far from perfect, but it's still by far the best tool we have to prevent the flu."
Wash your hands often with soap and hot water or use an alcohol-based hand sanitizer, Burke said. And sneeze or cough into your elbow. Avoid touching your eyes, nose or mouth with your hands.
"Stay home (if you're sick). You can even stay away from your other family members at home to try to decrease their risk of getting flu."
Flu symptoms include fever, headaches, body aches, cough or sore throat, stuffy or runny nose, chills, fatigue, nausea, vomiting and/or diarrhea.
Prescription antiviral drugs, such as Tamiflu, can reduce the severity and duration. But they work only if they are taken within two days of getting sick. (Remember: Antibiotics fight bacteria, not viruses.)
Most other treatments are for symptom relief, such as ibuprofen or acetaminophen to reduce fever and body aches. Cough syrups or menthol lozenges can relieve coughs and sore throat. If mucus drainage is a problem, try gargling with saltwater or nasal irrigation with a neti pot.
Natural or herbal remedies are used by some to relieve symptoms or boost immunity. They include Echinacea, astragalus, elderberry extract, yin chiao, probiotics and vitamin D. Even chicken soup or hot tea can relieve symptoms.
Flu can be dangerous
Health officials say the flu causes between 3,000 and 49,000 deaths and more than 200,000 hospitalizations each year. Complications are most common among very young children and people over 50, as well as people with chronic health conditions and pregnant women.
"There are definitely potential complications, pneumonia being one of the biggest ones," Burke said.
Patients should see a doctor if their flu symptoms abate after five to seven days and then reappear. That could be a sign of post-influenza pneumonia, Burke said. If you go to the doctor's office or urgent care, be careful not to spread your infection to others. Burke says her office asks people to wear surgical masks if they are ill.
Is bug worse this year?
Most flu cases have been influenza Type A H3N2, which tends to hit the elderly the hardest, said Dr. Zack Moore, medical epidemiologist with the North Carolina health division. "As we would expect with an H3N2-predominant season, there have been a lot of long-term care outbreaks and reports of severe illnesses and deaths in the elderly."
"I'm cautiously optimistic that flu activity might have hit a peak during the last week of December," Moore said. "Even if that's the case, we will still have a lot of flu going around for quite some time. I don't have any theories on why flu has been more severe this season beyond that every season is different."