An early flu season is hitting hospitals, pediatricians and schools in Mass.

Influenza is hitting Massachusetts early and hard. According to new data from the state’s Department of Public Health, flu severity is estimated to be "very high."

A total of 5,462 new flu cases were recorded last week, nearly double the number from the week before and significantly more than at this time in any of the past three years.

Flu hospitalization rates have also been rising steeply. The highest rates are among adults over 65. But children have also been hard hit. The second highest rate of flu hospitalizations was among children up to age 4, the report said.

Pediatricians are reporting a surge of patients visiting their offices with flu-like symptoms.

“It's been about 10 years since a really, really, really bad flu outbreak, and we're there again,” said Mary Beth Miotto, president of the Massachusetts chapter of the American Academy of Pediatricians.

On Thursday, the Boston Public Health Commission warned residents of a rapid and “concerning” rise in flu cases in the city. Last week alone, the agency said, there were more than 700 cases of flu reported. The number was nearly three times as high as the worst week during the prior flu season.

Flu infection rates have been muted over the past couple of years, experts said, as many people continued to wear masks and take other precautions to slow the spread of COVID. Now that fewer people are taking those steps to avoid infection, respiratory viruses — including flu and RSV — have increased.

Since the start of the current flu season in October, more than 1,700 flu cases have been reported in Boston. Black and Latino residents have been disproportionately impacted, the data show. City health officials also noted a rapid increase in influenza-related pediatric hospitalizations last week. Nearly 60% of all flu cases identified in Boston have been in children and teens.

The numbers do not surprise Miotto. They mirror what she has been seeing among her patients at the Mattapan Community Health Center, where she’s a pediatrician.

Last week, “It was flu, flu, flu, COVID and flu, flu, flu, flu, ” she said. “I think I had one [patient] who didn't have flu.”

While Miotto said pediatricians are managing the influx of respiratory viruses, their offices are busy. Miotto said families may need to be patient with staff and pharmacists who are working hard.

Cathryn Hampson, president of the Massachusetts School Nurse Organization, said respiratory viruses are “running rampant” in schools and keeping school-based nurses busy, too. Many staff and students are out sick, she noted.

“If we had seen this prior to COVID, school nurses might have been overwhelmed,” Hampson said. But, after the stress of the pandemic and the demands of daily coronavirus testing, “the bar for being overwhelmed kind of moved up,” she said.

On Monday, Rochelle Walensky, director of the federal Centers for Disease Control and Prevention, said flu-related hospitalizations at this time of year are higher than the country has seen in a decade. Health experts have been comparing this year’s numbers to 2009-2010, when H1N1, or swine flu, swept the country.

Unfortunately, Walensky said, “We are seeing lower rates of [flu] vaccination compared to this time last year.”

While most people recover from flu without hospitalization, the illness can be dangerous. So far, 21 children have died during the current flu season, according to the CDC.

Miotto urged everyone to return to the strategies learned during the pandemic to slow the spread of infectious disease: Get the flu vaccine, wash hands often, wear a mask in busy public places, and stay home when sick.

“We've forgotten that we have tools,” said Miotto. “I was so impressed with the public in that first year of COVID, we all really pulled together, and I think maybe [people are] tired.”