Influenza activity is rising across the United States, with levels higher than what is typically observed at this time of year, according to a November 6, 2026, report from the Centers for Disease Control and Prevention (CDC).
While respiratory syncytial virus (RSV) and COVID-19 levels remain low, the proportion of outpatient visits for influenza-like illness reached 3.2%, which is above the 2.9% national baseline, CIDRAP reported.
“This early-season influenza activity is currently higher than typically observed at this time of year, but an earlier increase in activity does not necessarily lead to a higher seasonal peak or greater overall severity,” the CDC said in its weekly FluView update.
H1N1 mutation drives early wave
The surge is linked to a mutated strain of the Influenza A H1N1 virus, specifically a version in the D.3.1.1 subclade that carries a new mutation called G155E.
Among hospitalized patients with subtype information, 99.2% had A(H1N1)pdm09, according to the CDC. The H1N1 virus has accounted for 80% of influenza cases nationwide since May 30, according to the CDC’s most recent weekly report.
Epidemiologist Caitlin Rivers of Johns Hopkins University told NPR that the timing is unusual, as new waves of respiratory viruses typically begin in the South. However, this season began in the West, a pattern that differs from most years when the East Coast is hit first. Medical Daily noted the 2026-27 season is running approximately two and a half months ahead of schedule.
Teens and young adults appear to have a weaker antibody response to the G155E mutation, which may allow the virus to spread more easily past their existing immunity. While there is currently no evidence that the mutation causes more severe illness, Ringler-Cerniglia of the Washtenaw County Health Department said that two of the emerging circulating viruses are included in the vaccine.
In San Francisco, test positivity rates have already surpassed last winter’s peak. The city’s rate is currently 23%, exceeding the previous season’s high of 20%, San Francisco Chronicle reported. California’s statewide uptick is approximately 17%—lower than last season’s peak of 33% but still climbing.
“Because of the close association of the West Coast with Asia, we saw that first in the U.S.,” said Dr. Peter Chin-Hong.
Flu cases increase while pediatric deaths reach five
CIDRAP reported that the CDC also identified two deaths of children due to the flu this week, bringing the seasonal total to five. Clinical laboratories reported that 9.1 percent of respiratory specimens tested positive for influenza during the week ending October 31, Clinical Lab Products reported. However, another report said that flu test positivity was 11.3% this week, an increase from 9.1% the previous week, primarily driven by influenza A.
The CDC’s preliminary in-season assessment classifies current severity as low across all age groups, though it noted this may change as activity increases. It is currently too early to determine which viruses may predominate or if there will be implications for flu vaccine effectiveness this season.
Hospitalization data for the week ending October 31 shows the following:
| Metric | Value |
|---|---|
| Clinical laboratory test positivity | 9.1 percent |
| Highest hospital admission rate (age 65+) | 7.9 per 100,000 |
| Cumulative hospitalization rate (FluSurv-NET) | 6.0 per 100,000 |
Nationally, this season has seen at least 2.6 million flu cases, 36,000 hospital admissions, and 2,100 deaths. New admissions are projected to range from 6,900 to 30,100, while emergency department visits are projected between 1.6% and 6.7%.
“Cases are high,” said Dr. Brad Hare, chief of infectious diseases at Kaiser Permanente San Francisco. Rakesh Chaudhary, physician-in-chief at Kaiser Permanente Santa Clara, said that hospital activity in his area already feels similar to the middle of winter, typically seen in January and February.
Vaccination and regional availability
The CDC recommends an annual flu vaccine for everyone six months and older. Medical Daily said that protection from a shot takes about two weeks to build. According to the agency, prescription antivirals ought to be administered as soon as possible, especially for those with a higher risk of developing complications.
In San Francisco, Dr. Brad Hare emphasized the importance of immunization, stating, “If people were putting (vaccination) off, that’s the number one thing people need to do right now to protect themselves this season,” San Francisco Chronicle reported. For those who received a shot in September, Chin-Hong said that a second shot is not required, as the agency currently recommends only one flu shot per year.
In New Mexico, the Las Cruces Public Health Office provides immunizations for residents both with and without health insurance. At the Las Cruces Public Health Clinic located at 1170 N Solano Dr., flu and COVID-19 vaccines are available to adults without health insurance. NMSU Round Up reported that customers without insurance can use a coupon at Walmart to reduce the cost of a vaccination from $41 to approximately $21 as of November 2, 2026.
Individuals should seek emergency medical care immediately if they experience difficulty breathing or shortness of breath, chest pain or pressure, confusion, or signs of dehydration such as dizziness or very little urination, according to Stony Brook Medicine.