State health officials are warning that influenza is now widespread across the state, with the number of cases sharply on the upswing with weeks to go before the expected peak of the flu season.

In its report for the week ending Dec. 28, the state Department of Health said flu activity was now deemed high in all areas of the state for the first time this season. In addition, the percentage of the patients treated in emergency rooms for flu-like symptoms is on the upswing, as well as the percentage of those who tested positive for the flu in rapid tests.

The main culprit this season is overwhelmingly the B/Victoria strain, officials say, with 587 of a total of nearly 700 cases reported in New Jersey last week, up from 304 of the strain as of Dec. 21. Officials with the federal Centers for Disease Control authorities say the current vaccine does include some protection against the strain, which in addition to typical symptoms — fever and chills, headache, cough, muscle and body aches and fatigue — also afflicts some with vomiting and diarrhea.

Health care workers in the state say the statistics match their experience on the ground. On any given day, staffers at Summit Medical Group’s four clinics see about 250 patients. Lately, though, more than 400 have crowded the waiting rooms, and flu cases have jumped 40% over the last couple weeks. Most staffers now wear protective masks, and the sickest patients get isolated to a separate area in the clinic.

Dr. Corey Smith, medical director of emergency medicine at Summit Medical, said he’s seeing victims with fevers over 103 degrees, some passing out from dehydration.

“You have some people saying, ‘I’ve never seen my husband as sick as this before,’” he said. “We almost just can’t even keep up.”

Meanwhile, emergency room doctors at St. Peter’s University Hospital in New Brunswick have also reported a rapid escalation of cases.

“Many of us are seeing three, four, six cases of influenza a shift, now,” said Dr. Daniel Boutsikaris, an attending physician at St. Peter’s, up from one or two a week. “We’re still in the middle of the flu season, so how that will pan out for the rest of the flu season is hard to tell.”

The situation in New Jersey matches the rest of the country, federal officials report.

CDC data shows how reported flu cases have spread across the nation, starting back in October with slightly elevated numbers in Louisiana. As of Dec. 28, more than 55,000 cases have been confirmed since the end of September — two of three the B strain of the flu virus.

In New Jersey, the victims have included one death, a child.

State health officials say they expect a worse flu season this year than last. The season typically runs into April.

“We look at how many children are absent from school, we look at how many outbreaks are in nursing homes, we look at visits to emergency departments,” said Dr. Edward Lifshitz, medical director of the Communicable Disease Service at the state Department of Health. “There’s no particular part of the state — or no particular part of the country, really — which is not experiencing an outbreak of the flu.”

Doctors say it still makes sense to get vaccinated.

“You may get sick, but the degree of illness you’ll get is likely to be significantly less. And for those who are at high risk of complication of flu, their risk of death is much less,” said Boutsikaris.

Health professionals advise patients who experience trouble breathing to see a doctor. And those who get sick, should stay home and not muscle through a workday at the office.

“Simply, people are underestimating the value of staying at home, staying in their beds, hydration, using Tylenol and ibuprofen to get through this,” Smith said.