Influenza has arrived in the United States approximately two and a half months earlier than the typical seasonal pattern, according to Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. This timeline has not been observed since the 2010 season. While the Centers for Disease Control and Prevention (CDC) currently classifies overall flu activity as low, with 16,000 recorded flu-related hospitalizations, officials expect infections to rise significantly in the coming weeks as the virus spreads through the Midwest and East Coast.
Early Onset and Strain Characteristics
The early arrival of the virus may be linked to travel patterns, though Dr. Amesh Adalja, an infectious disease specialist at Johns Hopkins Center for Health Security, noted there is no definitive explanation for the timing. The dominant strain this season is an H1N1 virus carrying a specific mutation known as G155E. This genetic feature resembles characteristics of H1N1 strains that circulated before 2009.
Early research indicates that individuals under the age of 25 have less immunity to this particular variant. The virus appears to bypass some of the protective immunity generated by prior infections and vaccinations in younger populations. So far, the season has seen one reported pediatric influenza-associated death involving an elementary-aged child from outside the Denver metro area. For context, the 2025-26 season resulted in an estimated 24,000 flu-related deaths, including 198 children.
Dr. Alex L. Greninger, head of infectious disease diagnostics at the University of Washington, emphasized that individual health factors play a larger role in severity than the virus itself. People with diminished cardiorespiratory capacity or recent heart disease are at higher risk of severe complications when infected.
Vaccine Match and New mRNA Options
The World Health Organization (WHO) selects flu vaccine strains in February based on global data, aiming to predict the dominant variants for the upcoming northern hemisphere winter. This year, the forecast missed the mark. The specific variant that emerged after the vaccine formulation was finalized means the current flu vaccine is a weaker match against infection.
Despite the mismatch, Osterholm stressed that vaccination remains critical. He compared the vaccine to a seatbelt, noting that while it may not prevent infection entirely, it significantly reduces the risk of severe disease, hospitalization, and death. The vaccine composition was not affected by the US withdrawal from the WHO, as the CDC participated in the strain selection process and the US uses the same strains as Canada and Mexico.
This season introduces the first publicly available mRNA-based flu vaccine, mFlusiva, developed by Moderna. Recommended for adults aged 50 and older, this group faces the highest risk from influenza. Osterholm noted that mFlusiva produces milder reactions than mRNA COVID-19 vaccines. Adalja expressed hope that mRNA technology will allow for faster strain selection closer to the start of flu season, improving future vaccine matches.
Guidance Amid Advisory Committee Changes
With approximately two weeks required for the body to build protective antibodies, experts advise getting vaccinated before the holiday travel season. Osterholm encouraged everyone to get both a COVID booster and a flu shot, noting that mild reactions are preferable to contracting the flu.
Access to reliable guidance has become complicated due to recent changes in US health administration. In 2025, Health Secretary Robert F. Kennedy Jr. fired the entire CDC vaccine advisory committee. A federal court has since halted the new panel’s votes, leaving the CDC relying on last year’s recommendations. Osterholm confirmed that the Advisory Committee on Immunization Practices effectively does not exist in its current form.
Major medical organizations, including the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, have stepped in to provide coordinated recommendations. These groups, drawing on an evidence review by Osterholm’s research center, advise flu shots for everyone six months and older, including pregnant individuals. Adalja recommended consulting these groups rather than the CDC for current advice, citing concerns about data integrity.
For those who become ill, at-home antigen tests for influenza A, influenza B, and respiratory syncytial virus are widely available. Testing is recommended to help doctors prescribe antivirals like Tamiflu or Xofluza, which can reduce hospitalization risks and recovery time. Experts advise staying home when sick and wearing an N95 mask if leaving the house is necessary to protect vulnerable populations.
Source: The Guardian
