New Jersey and Pennsylvania are in the red zone when it comes to flu, according to the U.S. Centers for Disease Control and Prevention.

That means that flu activity is high based on the percentage of outpatient medical visits prompted by influenza-like symptoms. This region is joined in this dubious distinction by New York, South Carolina, Missouri, Kansas, and Oklahoma.  By another measure, New Jersey and Pennsylvania are among the 35 states that had "widespread" flu activity at the end of January.

However you look at it,  this area has not seen the worst of this flu season yet.

"We're still on the rise," said Alexandr Zaslavsky, medical director for Patient First in Cherry Hill, Voorhees, and Sicklerville.  "It hasn't peaked."  He said he was seeing worse symptoms and more cases than last year at this time.

Robyn Baron, a medical director for Temple ReadyCare who most often works in Northeast Philadelphia, said she had seen an unusually high proportion of sick children among flu victims this year.  Some have been quite sick.  Over the weekend, she sent a 6-year-old boy to an emergency department after his parents carried him in with a 104-degree fever.

Fifteen children have died in the United States from flu this season, according to the CDC.  There were 148 pediatric deaths during the 2014-15 season and 89 last year.

The primary strains of virus that are circulating are covered in this year's vaccine.   Public health officials recommend the shots for everyone over the age of 6 months.

Zaslavsky said he  had "noticed a significant number of patients in comparison to last year that had the shot and still got the flu. In fact, I had the flu myself."

Chris Notte, medical director of ambulatory markets for Jefferson Community Physicians, said he sees some patients each year who got the flu even though they had the shot. "However, the preponderance of individuals presenting with flu-like illness didn't receive the flu shot," he said.

The government will weigh in soon about how effective this year's vaccine has been. The shots are never perfect, though the CDC says that in some cases, the vaccine may mean lighter symptoms even if recipients do get the flu.  Experts hope that getting lots of people vaccinated will reduce the chances of infection.

Notte, who works primarily in Bucks and Montgomery Counties,  said he thinks it's still not too late to get the shot.

For most people, the flu feels a lot worse than a typical cold.  It comes on suddenly, often with fever and chills.  Flu sufferers typically have respiratory symptoms, muscle aches,  headaches, and fatigue.  Vomiting and diarrhea are possible, but are more common in children than adults.

Children under 5 and adults 65 and older are at higher risk for flu complications such as pneumonia.   Zaslavsky said people should visit a doctor if they have fever above 100.4, severe body aches, and extreme fatigue.

Susan Coffin, clinical director of the division of infectious diseases at Children's Hospital of Philadelphia, said this is shaping up to be a busy flu season after a relatively mild one last year. Symptoms have been a little more severe this year.  People still have time to get a shot, she said, but also should be working to prevent disease.  Wash hands frequently and dispose of used tissues.

"You shouldn't send your kids to school while sick," she said. (This goes for adults at work as well.)  People with the flu are most infectious for about a half-day before they have symptoms and at the beginning of their illness.  The amount of virus they can spread declines markedly once they start feeling better.

Children should be home while they have fevers and significant symptoms, like a lot of coughing or nose blowing.  "It could be one or two days," she said, "or it could be a week."

The doctors had a little good news: The stomach bug that was making the rounds in January seems to be on the way out.