For the second year in a row, New Hampshire and the U.S. experience rough flu season
Dr. D., an epidemiologist at Dartmouth Hitchcock Medical Center in Lebanon. This flu season is “probably the third most severe among adults” in recent history, Michael Calderwood said.
USA Centers for Disease Control and Prevention As of March 28, there are estimated to be at least 30 million flu cases, 370,000 hospitalizations and 23,000 deaths in the United States this season, according to the most recent data available. 71 people died from flu in New Hampshire, according to New Hampshire Department of Health and Human Servicesincluding two children. The CDC currently rates New Hampshire as having “moderate severe” flu levels. The state’s southern neighbor, Massachusetts, is also classified as “moderately severe,” but there are “minimal” levels in Vermont and “low” levels in Maine.
The 2025-26 season lags behind the 2024-25 season, which Calderwood said was the worst flu season since 2011, especially for children. In the 2024-25 season, 289 children died from flu across the country. So far this flu season, 123 children have died. “The number is still coming in, so we don’t have a final forecast for this year,” he warns. The typical flu season lasts from early October to mid-May.
Calderwood said December was particularly difficult and hospitals were having a hard time keeping up. This year’s peak was New Year’s week, two weeks before last year’s peak, and it started to decline after that. Calderwood said most of this increase was influenza A, but influenza B was still circulating in March and April. Influenza B figures are nearly twice as high as in the same period last year.
According to the CDC, 5,701 positive influenza B tests were reported across the United States in the week ending March 21 (82.5% of all influenza cases) and 72,175 positive influenza B tests for the entire season to that point. Last year, 3,397 influenza B tests (40.6% of all cases) were performed in the week ending March 22, 2025, making the number 32,218 during the season.
Calderwood said this season has been particularly bad for childhood flu cases, which have negatively impacted schools.
“The weird thing this year was that the flu caused a lot more gastrointestinal illness,” he said. “So schools were seeing a lot of kids going home with more vomiting and diarrhea than typical respiratory illnesses.”
What worries him even more is that doctors are seeing an increase in cases of flu-related acute necrotizing encephalopathy.
“It’s a big, flashy name,” he said. “But what it really means is brain swelling with some sort of immune response that gets out of control. And about 1 in 4 people who come down with it die. And about two-thirds of those who survive are left disabled to some degree. And that’s something that’s vaccine-preventable.” Calderwood believes new strains are more likely to produce this symptom.
Calderwood suspects low vaccination rates and the vaccine’s poor match for this year’s newest strain of the virus are behind back-to-back difficult flu seasons. As of Feb. 22, an estimated 46.5% of U.S. adults reported getting a flu vaccine this year, according to the report. HKM. He said the country’s epidemiology community has a goal of reaching a 70% vaccination rate by 2030.
“The data showed that in 2024-2025, the vaccine prevented 10 million symptomatic illnesses, 5 million office visits, 180 thousand hospitalizations, 12 thousand deaths,” he said. “So vaccines have a huge impact. At the same time, we saw a 5% drop in kids getting vaccinated that season. And that’s a huge number considering that drop.”
She strongly recommends that parents get their children vaccinated against the flu starting at 6 months of age, when they are first eligible for vaccination.
“We’re seeing a huge amount of decline at this point,” he said. “And this is the group at highest risk of death.”
However, he recommends that adults also get vaccinated.
“We have very effective vaccines, we have very safe vaccines,” he said. “And understanding that that protection is something that is valuable to protect both yourself and those around you, especially people who are older or have compromised immune systems that mean they may not have as much protection.”
The elderly, infants, and those with medical conditions that affect their immune systems are most at risk for the most severe flu symptoms.
Calderwood believes next year epidemiologists will be able to better match the vaccine to the new strain of the virus.
The CDC has been rocked by mass layoffs since President Donald Trump took office in January 2025, but Calderwood said he was “impressed with the data we continue to receive.”
“There are certain areas where we don’t have that hard data anymore,” he said. “COVID monitoring is one of them. But there’s actually a really solid infrastructure for monitoring respiratory viruses at the national level, so our flu data, our RSV data, has continued to be something that we can rely on.”
As for his clinic in Lebanon, Calderwood said he sees mixed concern among his patients. Some are much more concerned, wearing masks and wanting to do whatever they can for prevention “and some scoff at the idea that we should do anything for prevention. And it’s really quite divided.”
