Doctors urge flu vaccination as early cases rise on West Coast
Health officials warn that a new H1N1 mutation may increase risk for younger people, prompting calls for early flu shots amid an early surge in cases.
Doctors are urging Americans six months and older to receive the flu vaccine after an unusually early increase in cases on the West Coast. The dominant strain this season is H1N1, the same virus that caused the 2009 pandemic, but it carries a new mutation known as G155E. Scientists say prior exposure to older H1N1 variants may offer only limited protection.
"What people are a bit worried about is that the H1N1 strain this year hasn't been seen by a lot of younger folk, so it may be more severe in them," said Dr. Jennifer Duchon, a pediatric infectious disease expert at Mount Sinai Children's Hospital.
The 2026-2027 flu vaccines, approved by the FDA in August, target H1N1, H3N2 and an influenza B virus. While the vaccine’s effectiveness varies, it has reduced flu-related hospitalizations and deaths by 30% to 60% over the past decade. Microbiologist Scott Hensley of the University of Pennsylvania noted that two of the three vaccine components appear well matched to circulating strains, but the H1N1 mutation could affect antibody response in younger individuals.
Epidemiologist Caitlin Rivers of Johns Hopkins observed that this season’s flu activity is originating from the West rather than the usual Southern states, though she said there is no clear explanation. Infectious Diseases Society of America chief executive Jeanne Marrazzo said early studies show antibodies from teens and young adults do not recognize the new mutation, but cautioned that the findings are not yet cause for alarm.
Flu vaccination rates have fallen, with about 58 million adults receiving a shot last season, down more than 20% from the pre-COVID-19 peak. Around half of children were vaccinated, compared with over 60% in 2019-20. The Centers for Disease Control and Prevention (CDC) halted its broad recommendation for most children at the start of 2025, a decision currently on hold after a court intervention, and paused its advertising campaign for flu shots.
"He has done what he can to discourage flu vaccination," said pediatric infectious disease expert Paul Offit.
HHS spokesperson Emily Hilliard referred to the CDC’s "Respiratory Illness Season Toolkit," which emphasizes vaccination as the most effective way to prevent serious illness. CDC data show flu activity remains low but has risen since late August, with positive test rates reaching a 10-year high for this time of year.
Public health officials continue to recommend early vaccination, especially for younger populations, as the season gains momentum.