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Influenza Health Advisory

Published: October 24, 2018

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Actions Requested of All Clinicians

  1. Encourage and facilitate flu vaccination for everyone age 6 months and older, and encourage and facilitate pneumococcal vaccination for those at increased risk of pneumococcal disease.
  2. Encourage all persons with influenza-like illness (ILI)* who are at increased risk for complications to seek medical care promptly.
  3. Treat all hospitalized patients with clinical signs and symptoms consistent with influenza. Use oseltamivir, zanamivir or peramivir.
  4. Send respiratory specimens (from both upper and lower respiratory tract) for confirmatory PCR influenza testing on all hospitalized patients with clinical signs and symptoms consistent with influenza, especially those in the ICU or fatalities. Sonoma County Public Health laboratory can provide PCR testing. Do not use rapid tests in this setting.
  5. Report to Sonoma County Public Health Disease Control 707-565-4566:
    - outbreaks of undiagnosed ILI* in residents of large group or institutional settings; and
    -individual lab-confirmed cases of seasonal influenza only if they meet the specific reporting criteria described below.
  6. Implement infection control precautions as described below. Note:
    1. ALL PERSONS with ILI* should be instructed to stay at home until 24 hours after fever resolves, except patients that require medical evaluation and care.
    2. ALL PERSONS with fever & cough should wear a facemask in common areas of all health care settings.
    3. All hospitalized patients with suspected or confirmed flu should remain in isolation for 7 days after illness onset OR until 24 hours after fever resolution whichever is longer.

*ILI (influenza-like illness) is temperature >37.8°C or 100°F and cough and/or sore throat, in the absence of a known cause.

Situational Update

Influenza activity within Sonoma County, California and across the nation is currently low. While at low levels, influenza is circulating in California. For weekly CDPH surveillance updates, go to:, and under “Surveillance Reports” click on the most recent report.

Influenza Surveillance and Reporting

Goals for influenza surveillance this season are to: (a) prevent and curb outbreaks in confined settings where the risk of transmission is high; and (b) monitor the epidemiology of severe and fatal cases of influenza.


  • Cases occurring among residents of group or institutional settings (e.g., long-term care, rehab, assisted living facilities, college dorms) in Sonoma County which are either: (a) lab-confirmed cases of influenza or (b) outbreaks of undiagnosed ILI.
    • Report by telephone to (707) 565-4566 within 24 hours
  • Fatal cases of lab-confirmed influenza in children < 18 years of age
    • As soon as possible (but no later than 7 days), complete case report form (see ) and fax to Sonoma County Disease Control at 707-565-4565 or call 707-565-4566 to speak with a public health nurse.
    • Note: Sonoma County Disease Control may request retained specimens from fatal cases, which will be forwarded to CDPH for viral culture, strain typing, and antiviral resistance testing in order to characterize the circulating strains, inform treatment recommendations and look for the emergence of novel strains.
    • Note: Severe and fatal cases of lab-confirmed influenza in persons 18 – 64 years of age is no longer required or requested
  • Cases of ILI with epidemiological characteristics (history of travel or recent close contacts or exposures within 10 days of symptom onset) suggesting variant influenza infection (e.g., swine (H1N2v or H3N2v)) or novel influenza infection (e.g., avian (H5N1 or H7N9)):
  • Report respiratory syncytial virus (RSV) – associated fatal cases age 0-4 years.

Influenza Testing, Specimen Collection and Submission

Rapid antigen tests may be useful when testing to help guide acute clinical care decisions. Rapid influenza tests may vary in terms of sensitivity and specificity, with sensitivities ranging from approximately 50-70%; false positives are common when influenza prevalence is low and false negatives can occur when influenza prevalence is high. In addition, a CDC study found that rapid flu tests have limited ability to detect variant influenza A viruses. More information is available here: . The Sonoma County Public Health Laboratory can perform additional testing by Polymerase Chain Reaction (PCR).
Influenza specimen collection and submittal instructions can be found at:
For testing questions, call 707-565-4711.

Vaccine for Influenza

The 2018-19 Trivalent vaccine contains an A/Michigan/45/2015 (H1N1) pdm09-like virus, an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus; and a B/Colorado/06/2017-like virus (Victoria lineage). Quadrivalent vaccines contain these antigens and also include a B/Phuket/3073/2013-like virus (Yamagata lineage).

Afluria Quadrivalent is now licensed for age’s ≥5 years. Fluarix Quadrivalent is now licensed for persons aged ≥6 months. Children aged 6-35 months may receive Fluarix Quadrivalent at the same 0.5 mL dose. Persons with a history of egg allergy of any severity may receive any licensed, recommended, and ageappropriate influenza vaccine (IIV, RIV4, or LAIV4). Flumist (LAIV) is an option for this 2018-19 season. A complete listing of 2018-19 flu vaccine products is posted at
Recommendations: Annual vaccination is recommended for everyone age 6 months and older who does not have contraindications, regardless of risk group. For persons whom more than one product is appropriate, no preferential recommendation is made for one product over another. An age appropriate vaccination should be used.

    • Children age 6 months through 8 years need 2 doses for 2018-19, administered at least 4 weeks apart if they have not previously received ≥2 doses of trivalent or quadrivalent influenza vaccine before July 1, 2018. The two doses of influenza vaccine do not have to have been administered in the same season or consecutive seasons. All children who have previously gotten two doses only need one dose this season.
      • Pregnant women may receive any licensed, recommended, and age-appropriate flu vaccine, except for LAIV4.
      • Children age 6 through 35 months must receive flu vaccine free of the preservative thimerosal, according to California law.
      • Persons who report an allergy to eggs: No change from 2017-18 season recommendations

ACIP recommendations for 2018-19:

Pneumonia vaccine age

Vaccine Information. The pneumococcal conjugate vaccine, PCV13 or Prevnar 13®, is currently recommended for all children younger than 2 years old, all adults 65 years or older, and people 2 through 64 years old with certain medical conditions. For the pneumococcal polysaccharide vaccine, PPSV23, Pneumovax23® is currently recommended for all adults 65 years or older, people 2 through 64 years old with certain medical conditions, and 19- 64 years old who smoke cigarettes.

Pneumococcal algorithm: &

Health Care Workers:

By order of the County of Sonoma Health Officer dated October 4, 2018 (originally issued on October 19, 2012), all health care workers at hospitals, skilled nursing facilities (SNFs), residential care facilities for the elderly (RCFEs), residential facilities for the developmentally disabled, and dialysis centers are required to receive an annual influenza vaccination or, if they decline, wear a mask in patient care areas during the influenza season. The full document is available at: In addition, CA law (Health
& Safety Code §1288.7 / Cal OSHA §5199) mandates either flu vaccination or the signing of a declination form for all acute-care hospital workers and most health care personnel including clinic and office-based staff.

Antiviral Treatment for Influenza

Antiviral medications can reduce illness severity, shorten duration of illness and length of hospitalization, and reduce risk of complications and mortality from influenza. Antiviral medications can also prevent disease. CDC guidelines for influenza antiviral use during 2018 – 19 season are not yet available but are expected in the next several weeks and will be located here: . We do not anticipate significant changes from 2017-18 recommendations, which include:

    • Use of three of the five licensed prescription influenza antiviral agents available in the US: oral oseltamivir (Tamiflu®), inhaled zanamivir (Relenza®), and intravenous peramivir (Rapivab®). All three are neuraminidase inhibitors that have activity against both influenza A and B.

Antiviral treatment as early as possible for suspected or confirmed influenza in:

    • Hospitalized patients;
    • Persons with severe, complicated, or progressive illness; and
    • Persons at higher risk for influenza-related complications.

Those at higher risk for influenza-related complications include:

    • persons age <2 years or ≥65 years;
    • persons with chronic pulmonary, cardiovascular, renal, hepatic, hematological, neurologic (including
      neurodevelopmental), and metabolic disorders;
    • persons with immunosuppression, including from medications or by HIV infection;
    • women who are pregnant or postpartum (within 2 weeks after delivery);
    • persons aged <19 years who are receiving long-term aspirin therapy
    • American Indians/Alaska Natives;
    • persons who are morbidly obese (i.e., BMI ≥40); and
    • residents of nursing homes and other chronic-care facilities.

Infection Control Precautions for Healthcare Settings

Preventing transmission of influenza virus and other infectious agents within healthcare settings requires a multi-faceted approach. Spread of influenza virus can occur among patients, healthcare personnel, and visitors; in addition, healthcare personnel may acquire influenza from persons in their households or community. The core prevention strategies include: administration of influenza vaccine, implementation of respiratory hygiene and cough etiquette, appropriate management of ill healthcare personnel, adherence to infection control precautions for all patient-care activities and aerosol-generating procedures and implementing environmental and engineering control measures. For more information go here:
Recommendations include:

  • Promote and administer seasonal influenza vaccine to both healthcare personnel and patients. See above for recommendations and for the Health Officer Order requiring healthcare workers in certain facilities in Sonoma County to receive an influenza vaccination or, if they decline, to wear a mask in patient care areas during the influenza season.
  • Take steps to minimize potential exposures using a range of administrative policies and practices.
  • Monitor and manage ill healthcare personnel
  • Adhere to standard precautions with all patients
  • Adhere to droplet precautions with all patients with suspected or confirmed influenza for 7 days after illness onset or until 24 hours after the resolution of fever and respiratory symptoms, whichever is longer, while a patient is in a healthcare facility. Specifically:
    • Request that all persons with fever and cough wear a face mask in common areas of healthcare settings;
    • Isolate unmasked patients with ILI as soon as possible, ideally in a private exam room or at a distance of at least 3 feet from others;
    • Staff entering the exam room of any patient with ILI should ensure either the patient is masked, or wear either a facemask or an N-95 respirator pending diagnosis.
  • Use caution when performing aerosol-generating procedures
  • Manage visitor access and movement within the facility
  • Monitor influenza activity
  • Implement environmental infection control (e.g. standard cleaning and disinfection procedures).

There are no data to indicate that the transmission characteristics of the swine variant influenza viruses (e.g., H1N2v or H3N2v) differ from those of seasonal influenza viruses. The infection control principles and actions relevant for seasonal influenza are appropriate for the control of the swine variant influenza virus infections.
If avian influenza A (H7N9 or H5N1) are suspected: use standard, contact and airborne precautions. For more information see:

Solicitation for Sentinel Providers for Influenza Surveillance

Primary care providers are invited to enroll as sentinel providers for influenza surveillance in Sonoma County. Compiling and reporting data usually takes less than 30 minutes per week. If interested in participating, contact the California Department of Public Health at or (510) 620-3737.

Additional Resources

Sonoma County Public Health: