(The Hill) — Despite a relatively slow start to the flu season, U.S. schools are preparing for an increase in absences and sick children as a new variant gains momentum.
The flu vaccine for the 2025-2026 season could be less effective against H3N2 subclade K, which has already caused spikes in hospitalizations in countries including Canada and the U.K.
Experts stress that the vaccine is still one of the best tools for avoiding a bad flu season and that children should stay home when they are sick, as schools are struggling with vaccine hesitancy and increased chronic absenteeism rates.
“Although the number of U.S. influenza viruses analyzed so far is low because of low domestic flu activity, most have been H3N2 viruses and, among those, H3N2 subclade K viruses have been most common,” the Centers for Disease Control and Prevention said.
While the vaccine may not be as effective against the new variant, experts stress some protection is better than none, and even a less effective vaccine can decrease rates of hospitalizations and the spread of the virus.
“Even an imperfect influenza vaccine — let’s say it shaves 30% off of your influenza risk — is still probably shaving even more off your risk of getting severe influenza, meaning you’re only 30% as likely to get the flu, but if you get the flu, your likelihood of getting severe flu is much, much lower,” said Ryan Maves, professor of infectious disease at Wake Forest University.
“Your likelihood of going to the ICU is much lower. Your likelihood of getting hospitalized is much lower, your likelihood of death is much lower. All of those things together cumulatively affect the risk and the efficacy of any given influenza vaccine and so, when we look at getting the flu shot this year, I don’t think it’s really a decision. The decision is, ‘How lucky do you feel?’” he added.
But vaccine rates have been dropping at U.S. schools, even among shots normally required for classrooms.
The CDC found that in the 2024-2025 school year, vaccination rates dipped to 92.1% for the diphtheria, tetanus, and acellular pertussis vaccine and to 92.5% for the measles, mumps and rubella vaccine and polio vaccine for kindergartners. For the 2019-2020 school year, vaccination rates for DTaP were at 94.9% among kindergartners, and MMR was at 95.2%, according to the CDC.
Exceptions for vaccines rose in the same school year to 3.6% from 3.3% the year before. Seventeen states had a more than 5% exemption rate. A community needs a 95% vaccination rate for herd immunity.
Currently, no state requires the flu vaccine for kids to go to school, and last year, flu vaccinations among students were less than 50%.
“You also have to recognize that vaccines are not just for each of us as individuals. They’re for everyone. If there are children in your child’s school who have immune suppression, who have leukemia, have other diseases, and if they get the flu or viral illness, they might get significantly more ill than a child who has a normal immune system or is not on drugs that may suppress their immune system,” said Ron Marino, a member of the Council on School Health Executive Committee at the American Academy of Pediatrics.
“We’re all in this together. We get a benefit to ourselves. We don’t transmit the disease to grandma and the people at home, and we protect other kids in the in the school setting,” added Marino, who is also the director of the Center for School Health at Mount Sinai South Nassau Hospital.
And schools and medical professionals say they are no longer receiving the same federal support they once had because of Health and Human Services Secretary Robert F. Kennedy Jr.’s vaccine skepticism.
Last flu season had some of the highest hospitalization rates in years, and more than 280 children died.
“That is a heartbreaking reminder of how serious the flu can be — nearly one-third of children hospitalized with the flu had no underlying health conditions but were largely unvaccinated. Each season is different, but last year reinforces why prevention, especially vaccination, is so important heading into this year,” said Sarah Nosal, president of the American Academy of Family Physicians.
One of the most effective measures against the flu, encouraging staff and students to stay home when sick, is also complicated by high rates of chronic absenteeism and staffing shortages among faculty.
Lynn Nelson, president of the National Association of School Nurses, said the old standard used to be a spike of more than 10% in chronic absenteeism could be a signal of a bad spread of flu in the school community.
But because of increases in chronic absenteeism since the pandemic, that method is no longer reliable.
“I think rather than look for a specific percent of students, you really have to look at symptoms that they present,” such as a “sudden high fever,” Nelson said.
Schools need “anecdotal information you get from parents on the phone about why they’re keeping their child out of school because if you’re seeing clusters of cases, it could be influenza, then people need to pay attention to that,” she added.