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State of California—Health and Human Services Agency
California Department of Public Health

October 3, 2022

All Californians

Health Advisory: Early Respiratory Syncytial Virus Activity and Use of Palivizumab

Key messages

  • Respiratory syncytial virus (RSV) activity is increasing in California.
  • Consider testing for additional respiratory pathogens besides SARS-CoV-2, including RSV.
  • Administer prophylactic palivizumab to high-risk infants and young children per AAP guidance.
  • Encourage parents and caregivers to keep young children with acute respiratory illnesses out of childcare, even if they have tested negative for SARS-CoV-2.
  • Discourage health care personnel, childcare providers, and staff of long-term care facilities from working while acutely ill, even if they have tested negative for SARS-CoV-2.
  • Encourage patients to receive influenza and COVID-19 vaccines this fall to protect themselves against those respiratory viruses this season.


Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis and pneumonia in infants and a cause of severe disease in adults older than age 65 years. Although RSV typically circulates during the winter, during the week ending September 24, 2022, 4.7% of respiratory illness specimens from surveillance in California tested positive for RSV, a level usually not seen until late November [Figure]. It is unknown how long this increased activity will continue.

Persons with RSV infection typically have fever, cough, wheezing and runny nose. Infants and young children may be irritable, lethargic, feed poorly and have no fever. Consider testing for RSV in patients with respiratory symptoms, especially those who test negative for COVID-19.

The American Academy of Pediatrics (AAP) has published interim guidance for using palivizumab during the current increase in RSV infection to prevent severe illness in high-risk infants and young children to supplement its standard recommendations for prophylaxis. The AAP continues to support the use of palivizumab in eligible infants in any region whenever rates of RSV activity are similar to a typical fallwinter season. The California Department of Public Health (CDPH) supports early administration of palivizumab per AAP guidance.

Persons with acute respiratory symptoms should stay home while ill, especially those who work in health care, childcare, or long-term care, even if they have tested negative for SARS-CoV-2.

While there are no vaccines yet to prevent RSV infections, CDPH strongly recommends seasonal
influenza vaccine and COVID-19 vaccine to help protect persons 6 months and older.

For more information

Figure: Percentage of RSV detections at clinical sentinel laboratories — California, 2017–2022

Early RSV Graph

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