Health authorities report an earlier-than-usual start to the respiratory virus season, with influenza activity rising across parts of the United States and Canada. Officials urge residents aged 6 months and older to receive updated seasonal vaccines as health systems track increasing test positivity and early localized outbreaks.
Fall respiratory virus season is arriving ahead of typical schedules. Health officials on both sides of the border report that seasonal influenza, COVID-19, and respiratory syncytial virus are beginning to circulate earlier than usual, prompting renewed pushes for annual vaccinations before winter peaks set in.
The San Bernardino County Department of Public Health urges residents to get vaccinated to protect themselves against respiratory viruses, including seasonal influenza, COVID-19, and respiratory syncytial virus. Respiratory infections can cause serious illness, hospitalizations, and in some cases, death.
Early Flu Activity Rises in the Pacific Northwest and Utah
In the United States, flu activity remains low overall but is rising nationwide, according to Centers for Disease Control and Prevention data. Public health specialists note that the Pacific Northwest and California are seeing particularly early rises in cases.
William Schaffner told Live Science that this particular year, flu appears to be starting early, like right now. These findings were supported by Dr. Kaylan Christianer, an assistant professor of medicine and primary care physician at the Columbia University Vagelos College of Physicians and Surgeons located in New York.
In Utah, Dr. Tamara Sheffield speaking from Intermountain Medical Center noted that influenza activity is running ahead of last year’s schedule, stating that they are having the number of cases now that they had starting in November last year.
In local Bay Area tracking, influenza test positivity stands at 9.88%, compared to 1.80% and 1.67% in comparable periods in 2024 and 2025, respectively. Regarding COVID-19, Bay Area test positivity measures 8.49%, contrasted with rates of 4.89% and 7.87% during the same periods in 2024 and 2025, respectively.
A similar trend is unfolding in Canada. National test positivity reached 4.7% between September 27 and October 3, much higher than the average 0.6% rate seen this time of year in 2023-2025, with much of the national increase driven by an uptick of cases in British Columbia and in large cities such as Toronto and Calgary.
“These measures protect you and the people around you, especially those at higher risk of severe infection.”
California Department of Public Health
People at elevated risk for severe complications from flu, COVID-19, and RSV comprise several groups: individuals living in nursing homes or similar residential facilities, people with compromised immune systems, adults 65 and older, children under 5 with a particular emphasis on those under 2, pregnant or recently pregnant persons, and anyone managing chronic medical conditions such as asthma, diabetes, severe obesity, or diseases affecting the heart, lungs, kidneys, liver, or neurological system.
H1N1 Strains Dominate Early Cases as New Vaccines Launch
Public health surveillance indicates that the current early season is dominated by the H1N1 virus. Official government statistics indicate that approximately 98 percent of laboratory-confirmed Canadian influenza cases since the conclusion of August belong to the H1N1 lineage.
Andrew Pekosz noted that this early season in the U.S., focused mostly on the West Coast, is dominated by this H1N1 virus, attracting significant attention because of that specific strain.
The flu is caused by three different viruses: H1N1 and H3N2, which both cause flu A, and the influenza B virus, given that a second subtype of influenza B used to circulate but is now thought to be extinct.
Ward commented on vaccine compositions, explaining that flu shot efficacy fluctuates annually based on the predominant regional strain, and that this season features a favorable match tailored to combat H1N1, notwithstanding the prevalence of H3N2 viruses across much of 2025. The Food and Drug Administration approved Moderna's mRNA seasonal flu vaccine in the summer to protect those aged 50 and older; this is the first flu season it will face, though Health Canada is still reviewing it.
For COVID-19, national test positivity figures show lower rates than at this time last year.
California Issues Respiratory Virus Immunization Guidelines
Public health departments across North America are strongly encouraging residents to receive updated immunizations. For the 2026-27 respiratory virus season, the California Department of Public Health issued guidelines stating that all children 6 months of age and older should obtain a flu immunization, that children between 6 and 23 months qualify for the COVID-19 vaccine, and that individuals aged 2 to 18 possessing risk factors or lacking prior vaccination history should likewise be immunized. Adults aged 65 and older, along with younger adults suffering from underlying health issues or risk factors, are advised to maintain up-to-date COVID-19 immunizations; simultaneously, RSV shots are suggested for individuals 75 and older, those aged 50 to 74 with specific medical conditions, anyone residing with or tending to high-risk individuals, and persons seeking extra defense.
In the City of Berkeley, health officials emphasize that everyone 6 months and older is encouraged to get their annual flu shot as soon as possible, and provide free flu vaccines through Berkeley Public Health at the West Berkeley Immunization Clinic where no ID or insurance is required. Similar outreach efforts are underway in Utah, where Intermountain Medical Center experts stress that getting vaccinated before peak transmission is vital to preventing severe complications, including secondary bacterial infections like pneumonia.
Medical professionals remind the public that building full immunity takes about two weeks following an injection. Alongside vaccination, agencies recommend standard hygiene measures—including frequent handwashing, staying home when ill, and wearing masks in healthcare or high-risk settings when regional transmission increases. Readers with questions about coverage should check with their health plan or health insurer, and are advised to consult qualified healthcare professionals or visit official public health websites for personalized guidance.
Readers should consult qualified healthcare professionals for medical advice, diagnosis, or treatment recommendations regarding respiratory illnesses and vaccinations.
