Influenza cases are on a significant rise across the Granite State.
Since mid-December, there have been exponential week-over-week increases in influenza-like illness and acute respiratory illness, with flu activity spreading across most counties, according to the New Hampshire Department of Health and Human Services.
In the last week of December, 6% of outpatient visits resulted in a positive influenza test and 10% of patients in those settings tested positive for respiratory illnes, statistics that already surpass the last flu season’s peak in February, 2025.
State epidemiologist Benjamin Chan said this season is unique because of a genetically mutated influenza A strain called H3N2 that is primarily present in the United States.
“[It is] slightly different from what is currently covered in this year’s flu vaccine,” Chan said. “Now that doesn’t mean that the flu vaccine doesn’t work. It just means that people should still consider getting vaccinated to protect themselves against the more serious of the influenza viruses that the vaccine is still expected to provide protection against.”
Nationally, there has been a decrease in influenza vaccinations. There have been over 130 million vaccines delivered as of December 13, 2025. Over 192 million vaccines had been administered by the same time in 2020, according to the Centers for Disease Control and Prevention.
Chan said New Hampshire has historically had higher rates of flu vaccinations than the national average, with 45% of children and adolescents and 53% of adults receiving a vaccine. This year seems to be no different.
The state Department of Health and Human Services has reported 12 flu-related deaths so far this season, which is below the epidemic threshold calculated based on past seasonal trends. Chan said, on average, 40 people die each year from influenza.
“Anybody dying from the flu is definitely a concern,” he said. “That’s exactly the reason for people to consider getting vaccinated, because vaccination protects against those more serious complications of influenza, including deaths.”
What is also a concern for Chan is the percentage of influenza testing at New Hampshire hospital labs, which at between 30% and 35%, is “quite high.” The Dartmouth Hitchcock Medical Center lab found 244 confirmed flu cases in December 2024 — that number jumped to 877 last month.
Chan advised Granite Staters that the best way to fend off serious complications from the flu is to get the latest vaccine that protects against three viral strains. He also advised to stay home if one is feeling under the weather, wash hands regularly and cover ones mouth and nose when coughing or sneezing.
“We’ll continue to monitor what’s going on with flu this season, and so the situation may change,” Chan said. “But it’s shaping up to be a highly active and more severe flu season than what we may have seen in the past.”