Flu is spreading around the Philly region and the nation. The holidays could help it take off.

It’s still early in the flu season, but it looks as if we’re in for a tougher time this year than last, when COVID-19 precautions practically drove that other respiratory virus underground.

This year, flu is off to a faster start and contagion is increasing, especially among children and young adults, according to the CDC.

Public health officials have been warning for weeks that flu could be rough this year as people tired of masking and social distancing and, emboldened by COVID-19 vaccines, gather inside. Those who are not newly vaccinated for flu may have less immunity than usual because so few people caught the virus last year.

The late fall and winter picture could be complicated and confusing as two powerful respiratory viruses with very similar symptoms spread at the same time. It’s possible to be infected with both at once, and both can spread without symptoms. A possible surge of both viruses, which some have labeled a twindemic, could further strain health-care and testing providers.

Some college campuses are already reporting outbreaks of flu, which doesn’t bode well for parents and grandparents as students head home for Thanksgiving. Rowan University has had about 180 cases since Nov. 1, although the numbers are falling now. The University of Michigan has had almost 700 cases this month. Schools in Florida and Georgia, as well as the University of Mississippi, are also reporting cases.

The Pennsylvania Department of Health said it was not aware of any college outbreaks in the commonwealth. The University of Pennsylvania, which began requiring students to get flu shots this year, has not yet had any cases, said Mary Kate Coghlan, director of communications, student wellness. At Pennsylvania State University, 273 students have tested positive for flu, more than usual for this time of year. Wyatt DuBois, assistant director of public relations, said the university is using a more sensitive test this year and testing demand is high as students prepare to travel. “University Health Services is taking this trend seriously and is in close contact with local and state health authorities and they are offering guidance at this time,” he said.

The Michigan outbreak, though, was large enough to attract the attention of the CDC, which sent investigators. In a university announcement, Juan Luis Marquez, medical director at the Washtenaw County Health Department, said, “While we often start to see some flu activity now, the size of this outbreak is unusual.”

He said those cases wouldn’t necessarily affect the local community immediately, “but it does raise concerns about what the flu season may bring.”

Philadelphia-area health leaders also worry about what will happen as infected students fan out across the country. “It’s really the makings of a spreader event,” said David Cennimo, an infectious-diseases specialist at Rutgers New Jersey Medical School.

So far, he said, the situation looks different than it did last year, but it does not yet seem unusually dire. “It really looks like we’re back to normal,” he said.

» READ MORE: US advisers support expanding COVID boosters to all adults

Tina Tan, state epidemiologist for the New Jersey Department of Health, said it’s troubling that the predominant strain of flu so far is A(H3N2). That type, she said, is “sometimes associated with a more severe flu season.” That could mean both sicker patients and more cases.

Amber Liggett, a public information officer for the Pennsylvania Department of Health, said her agency is also worried about the early arrival of H3N2. “H3N2 is known to cause more complications and deaths, and seasonal vaccines are known to have lower efficacy against it,” she said.

Last year’s very low flu numbers created a challenge for vaccine makers: predicting which strains of flu would make the rounds this year, Cennimo said. Normally that’s based on what happens in the Southern Hemisphere, but very little did. This year’s shot protects against a version of H3N2 found in Cambodia in 2020. It’s too soon to know how well it will work.

The CDC said Friday that overall flu numbers were low but increasing during the week ending Nov. 13. Ninety percent of cases were among children and young adults aged 5 to 24. While this group is not at high risk for serious illness, it can play a key role in spreading the virus to more vulnerable younger children and older adults.

New Mexico stood out for having high flu activity. The CDC put Pennsylvania and New Jersey in the “low” category. Activity in Delaware was “minimal.” So far, there have been no pediatric deaths in the country, but Pennsylvania reported that one adult over 65 has died of flu this fall.

In its report for the week ending Nov. 13, Pennsylvania’s Health Department said cases had increased significantly in the last week. They were slightly higher than they had been for that time period during any of the last eight years. The department said there have been more than a thousand laboratory-confirmed cases so far, and they have been found in 52 of 67 counties.

Liggett said testing has increased because of concerns about COVID-19, and that makes yearly comparisons difficult.

New Jersey itself described flu activity as “moderate” overall for the week ending Nov. 13. It was low in southeast New Jersey and moderate in the southwest. So far, the activity level is similar to what was seen in 2018-19 and 2019-20.

Philadelphia, meanwhile, has had “almost nothing” — just five cases, said James Garrow, a spokesperson for the Philadelphia Department of Public Health. Flu typically hits hardest after the new year, he said.

Every year, public health experts say everyone over 6 months old should get a flu shot. They say that’s especially important this year because COVID-19 is also circulating.

According to the CDC, the flu vaccination rate for children is lower this year than last. As of the week ending Nov. 6, 35% had been vaccinated compared with 40.3% at that time last year. Data from October showed vaccination rates among pregnant people were down by 17 percentage points, from 58.2% last year to 40.8% this year. The news was better for all adults. A survey conducted in early November on whether adults had either already been vaccinated or intended to get a shot projected that vaccination coverage this season would be 58.5%, up 3.7 percentage points from last season. When the survey was conducted, 40.9% of respondents said they had already been vaccinated.

Flu usually announces itself suddenly with fever, chills, and body aches. Other symptoms include cough, sore throat, runny or stuffy nose, headaches, fatigue, and sometimes vomiting and diarrhea, according to the CDC. It tends to be most dangerous for very young children and people over 65. COVID-19 can cause these symptoms, as well. It is most dangerous for seniors, but people with obesity and many chronic illnesses are also at high risk.

Tan said the symptom most likely to differentiate COVID-19 from flu is loss of sense of taste or smell, which is much more common in COVID-19.

Most people will not be able to tell what they have without testing. “It’s going to be very difficult to distinguish the flu vs. COVID just simply based on symptoms,“ Tan said. Sick people, she said, should stay home to protect others.

Cennimo said we don’t all have to rush to the hospital the minute we get a fever. “Many of us, especially if we’ve been vaccinated, should be OK,” he said.

However, people who are at high risk for serious illness or are experiencing serious symptoms such as difficulty breathing should definitely seek medical help. Antiviral medications are available for flu and COVID-19, and patients with COVID-19 can get monoclonal antibodies. All must be given early in the course of the disease.

It takes two weeks for flu vaccines to become effective, so health officials said you should get one as soon as possible. And, many people still need COVID-19 shots and boosters.

“All roads lead to: Protect yourself with the shot,” Cennimo said.