About RSV

Respiratory syncytial (sin-SISH-uhl) virus, or RSV, is a common respiratory virus that usually causes mild, cold-like symptoms. Most people recover in a week or two, but RSV can be serious, especially for infants, older adults and those with weakened immune systems. RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the lungs) in children younger than 1 year of age in the United States. RSV circulation in the United States usually starts during fall and peaks in the winter. The timing and severity of RSV circulation can vary from year to year.

Several vaccine-like products are available to prevent RSV. RSV vaccines can be coadministered with seasonal flu or COVID-19 vaccines, and it is highly recommended to stay up to date on all three for optimal protection. See the LAC DPH RSV Immunization Information page for details.

In LA County
Local Data

Los Angeles County respiratory surveillance information is summarized during the respiratory virus season. View the most recent data on our RespWatch data dashboard. You can sign up to receive this free report delivered to your inbox every week.

News & Updates
  • CDC Health Advisory: Urgent Need to Increase Immunization Coverage for Influenza, COVID-19, and RSV Immunizations and Use of Authorized/Approved Therapeutics in the Setting of Increased Respiratory Disease Activity During the 2023 – 2024 Winter Season (12-19-23)
  • News Release: As Winter Viruses Increase, New Data Dashboards Allow Residents to Monitor Transmission Trends in Los Angeles County (12-7-23)
  • CDC Health Advisory: Limited Availability of Nirsevimab in the United States--Interim CDC Recommendations to Protect Infants from RSV during the 2023-2024 Respiratory Virus Season
  • CDPH Health Advisory: Preparation for Respiratory Virus Season (COVID-19, Influenza and RSV) (10-12-23)
  • LAC DPH Health Advisory: Prevent Severe RSV in Infants with Maternal or Infant Immunization (10-6-23)
  • LAC DPH Health Advisory: Immunize Infants and Older Adults to Protect them from Severe RSV (9-6-23)
  • CDC Health Advisory: Increased Respiratory Virus Activity, Especially Among Children, Early in the 2022-2023 Fall and Winter (11-4-22)
Symptoms & Treatment
Common Symptoms

In most people, RSV causes a mild, cold-like illness that lasts for 1-2 weeks. Symptoms usually appear 4 to 6 days after getting infected, and they usually appear in stages. Symptoms of RSV infection usually include:

  • Runny Nose
  • Decrease in appetite
  • Coughing
  • Sneezing
  • Fever
  • Wheezing

In very young infants with RSV, the only symptoms may be:

  • Irritability
  • Decreased activity
  • Breathing difficulties*

*Call your healthcare provider right away if you or your child is having difficulty breathing, not drinking enough fluids, or symptoms are getting worse.

In severe cases, the airways that lead to the lungs may become inflamed and cause breathing problems. RSV usually does not cause hospitalization in healthy adults, but it can lead to bronchiolitis and pneumonia in some cases.

Higher-Risk Individuals

People most at risk of serious illness from RSV infection include:

  • Premature infants
  • Young children with congenital (from birth) heart or chronic lung disease
  • Young children with weakened immune systems due to a medical condition or medical treatment
  • Children with neuromuscular disorders
  • Adults with weakened immune systems
  • Older adults, especially those with underlying heart or lung disease

Most RSV infections go away on their own in a week or two. There is no specific treatment for RSV infection, but you can take the following steps to relieve symptoms:

  • Manage fever and pain with over-the-counter fever reducers and pain relievers, such as acetaminophen or ibuprofen. Never give aspirin to children.
  • Drink enough fluids to prevent dehydration (loss of body fluids).
  • Talk to your healthcare provider before giving your child nonprescription cold medicines. Some medicines contain ingredients that are not good for children.
Transmission & Prevention

People infected with RSV are usually contagious for 3 to 8 days and may become contagious a day or two before they start showing symptoms. Some infants, and people with weakened immune systems, can continue to spread the virus even after they stop showing symptoms, for as long as 4 weeks. RSV can spread when:

  • An infected person coughs or sneezes
  • Virus droplets from a cough or sneeze get in your eyes, nose, or mouth
  • A person has direct contact with the virus, like kissing the face of a child with RSV
  • A person touches a surface that has the virus on it and then touches their face before washing their hands. RSV can survive for many hours on hard surfaces such as tables and crib rails. It usually lives on soft surfaces such as tissues and hands for a shorter amount of time.
General Prevention Measures

The following are steps that can be taken to prevent the spread of RSV:

  • Cover your coughs and sneezes with a tissue. Cough or sneeze into your elbow, not your hand.
  • Wash your hands often with soap and water for at least 20 seconds. If you can't wash your hands, use an alcohol-based hand sanitizer with at least 60% alcohol.
  • Avoid close contact, such as kissing and shaking hands with others.
  • Stay home from work or school when sick, until you have been fever-free for 24 hours and symptoms are mild and improving.
  • Avoid sharing cups and eating utensils with others.
  • Clean frequently touched surfaces.
Vaccines and Vaccine-like Products

Safe and effective vaccines and immunization products are available for:

  • Infants
  • Pregnant people
  • Adults 60+ years old
These products can prevent severe RSV disease in infants and older adults. Although these products are highly effective at preventing severe disease, they are not fully protective against all RSV infections so people who are high risk should continue to take the above prevention precautions in addition to receiving these products. See the LAC DPH RSV Immunization Information page for details.

LAC DPH RSV Fact Sheets
Information for Healthcare Providers
Information for Schools and Early Care Education Sites
What Parents Need to Know
Prevention for Older Adults
How to Reduce the Risk
Additional Information
CDC's RSV Information Page
LAC DPH Respiratory Virus Information Page
LAC DPH RSV Immunization Page
Additional Information
Additional Health Education Materials

Public Health has made reasonable efforts to provide accurate translation. However, no computerized translation is perfect and is not intended to replace traditional translation methods. If questions arise concerning the accuracy of the information, please refer to the English edition of the website, which is the official version.

Los Angeles County Seal: Enriching lives through effective and caring services