Skip to main content

Health Advisory: High Seasonal Influenza Activity

Disease Prevention and Control

Situational Update

As of November 7, 2026, influenza activity is very high and increasing in San Francisco and the Bay Area. Hospitalizations are currently at low levels. In the Bay Area, most influenza cases are due to influenza A viruses — the predominant subtype has been (H1N1)pdm09 both locally and nationally.

Influenza vaccination remains the most effective tool to prevent severe illness in vulnerable populations and reduce the overall burden of influenza disease. Antiviral treatments are available and recommended for hospitalized patients with suspected or confirmed influenza and people who are at high risk for severe illness. Receiving prompt treatment can reduce the risk of severe illness, hospitalization, or death.

Actions Requested of SF Clinicians

  1. Recommend the 2026-27 influenza vaccine to everyone 6 months and older who have not yet received a dose of the seasonal influenza vaccine.
    1. Administering vaccination now will provide protection during the upcoming holiday season. People can receive the influenza vaccine at the same visit they receive the 2026-27 COVID-19 vaccine.
  2. Test for seasonal influenza in patients with respiratory illness.
    1. Multiplex molecular panels are recommended when multiple respiratory viruses are co-circulating.
    2. Respiratory testing can guide clinical management, treatment, and infection prevention and control measures.
  3. Treat with influenza antiviral medications as soon as possible. Do not delay treatment while waiting for lab results.
    1. For hospitalized patients, treat immediately with oseltamivir.
    2. For outpatients at increased risk for severe disease, oseltamivir or single-dose baloxavir (ages ≥ 5 years) can be given.
  4. Report to the SFDPH Communicable Disease Program (628-217-6100):
    1. Acute respiratory outbreaks in congregate settings.
    2. Any suspected avian influenza A (H5N1) cases in patients with respiratory illness and/or conjunctivitis and recent exposure to sick or dead birds, recent consumption of raw dairy products, or other exposure risk factors for H5N1.
    3. Any pediatric influenza-associated deaths in laboratory-confirmed cases.
    4. Any potential cases of Acute Necrotizing Encephalopathy (ANE)
  5. Remind patients to wear a high-quality mask, such as a KN95, in crowded indoor spaces and to practice good hygiene, using soap and water or alcohol-based hand sanitizers.
  6. Encourage patients to stay home from school or work until they have been fever-free for 24 hours without fever-reducing medication and other acute symptoms have resolved.

Resources

Influenza

Avian Influenza A (H5N1)

Program Contact Information

Communicable Disease Program | Communicable Disease Branch
Population Health Division | San Francisco Department of Public Health
Tel: (628) 217-6100 | Email: cdcontrol@sfdph.org

View or sign up for SFDPH Health Alerts, Advisories, and Updates at sf.gov/healthalerts