Respiratory Syncytial Virus (RSV)

About This Disease

Respiratory Syncytial Virus (RSV) is a common illness that affects the nose, throat, and lungs. It is the most common cause of hospitalization in babies less than 1 year old, and up to 180,000 adults over 50 years old are hospitalized with RSV each year in the United States (U.S.) Luckily, RSV protection is available. Local patterns of infection are different than those seen in other parts of the US. Therefore, RSV protection is recommended year-round in Hawai’i.

People at higher risk for severe disease include premature infants, children less than 2 years old, people with chronic lung or heart conditions, people with weakened immune systems, and older adults. RSV is the most common cause of bronchiolitis and pneumonia in infants less than 1 year old. Two to three out of every 100 infants under 3 months old are hospitalized with RSV every year in the US. Severe cases in the hospital with breathing difficulties may need oxygen, Intravenous (IV) fluids, suctioning of mucus from the airways, and possibly intubation (a breathing tube inserted through the mouth into the windpipe) with mechanical ventilation (a machine to help with breathing).

People can easily be exposed to RSV because, while it can cause severe illness in some groups, most people experience mild, cold-like symptoms. People can even spread RSV a day or two before they have symptoms. Transmission occurs by touching a surface that has the virus on it, close contact with an infected person, or inhaling droplets when they cough or sneeze. The best ways to protect yourself are to wash your hands with soap and water, avoid touching your face with unwashed hands, avoid close contact with sick people, and clean contaminated surfaces.

The good news is that there are ways to protect those at higher risk:

Infants should receive a medication (RSV monoclonal antibodies) if younger than 8 months old and their mother was not vaccinated during that pregnancy.
Pregnant people should get the maternal RSV vaccine between 32-36 weeks to protect their newborn. The RSV vaccine is only given once, so for future pregnancies the infant should receive RSV antibodies.
All adults 75 years old and older, and adults 50-74 years old with risk factors (due to chronic health conditions or living in a nursing home) should get vaccinated.

See recent RSV trends in Hawai’i.

Signs and Symptoms

RSV symptoms usually begin 4 to 6 days after exposure. Symptoms usually begin with a runny nose and decreased appetite, followed by coughing and sneezing. Some people may have a fever or start wheezing. Some adults infected with RSV have mild or no symptoms. In very young infants, irritability, decreased activity, decreased eating and drinking, and breathing difficulties may be the only symptoms to arise. Most people fully recover in about 1 to 2 weeks.

Transmission

RSV is spread by close personal contact (such as kissing the face of a child that has RSV), inhaling droplets in the air after an infected person has coughed or sneezed, or touching an object or surface contaminated with RSV and then touching your mouth, nose, or eyes. RSV can survive on contaminated surfaces for many hours and on soft surfaces, such as tissues and hands, for a shorter period of time.

Diagnosis

Healthcare visits for illness due to RSV are very common. Illness caused by RSV is usually diagnosed through clinical exam and patient history. Providers may order testing in some cases, such as high-risk infants or patients with severe symptoms.

Treatment

RSV is currently treated by supportive care and treatment to improve certain symptoms. There is no specific antiviral medication to treat RSV once a person is infected, and research is ongoing.

Risk in Hawaii

Infection with RSV is very common. Almost all children will have had an RSV infection by 2 years of age. There are two main sources of information to look at current infection rates.

The Hawai’i Department of Health (DOH) tracks trends in the percent of tests for RSV that are positive and the percent of all hospital admissions that are for people infected with RSV. Click here to see recent RSV trends in Hawai’i.

CDC’s National Respiratory Enteric Virus Surveillance System (NREVSS) is a laboratory-based system that monitors respiratory and enteric virus activity including RSV. Data are available down to the regional level (Hawai’i is located in HHS Region 9). Click here to view national and regional data.

Prevention

The best ways to prevent any respiratory infection are to wash your hands with soap and water, avoid touching your face with unwashed hands face (especially mouth, nose, and eyes), avoid close contact with sick people, and clean contaminated or frequently touched surfaces.
The best ways a sick person can prevent further spread are to stay home from school or work, cover their nose and mouth when sneezing and coughing, wear a facial mask, wash their hands frequently, and avoid other close contact, such as kissing their children while sick.

Immunization recommendations:

There are different RSV immunizations for different people. Talk to your healthcare provider to learn more about your options.

Pregnant people should get a one-time dose of the vaccine, Abrysvo, between 32 and 36 weeks of pregnancy to protect their babies. The vaccine is recommended for pregnant people during RSV season, which is usually from September through January in the United States.
Infants and some young children should get monoclonal antibodies to protect them against RSV. Two monoclonal antibody products, clesrovimab and nirsevimab are available and are recommended for different situations.
For adults ages 75 and older, and those who are ages 50-74 and are at increased risk for RSV, there are three RSV one-time vaccines recommended: Arexvy, mResvia, and Abrysvo.

Additional Resources

Information for Clinicians

RSV is the leading cause of infant hospitalization in the U.S. Out of every 100 infants with RSV infection, 25-40% will develop bronchiolitis or pneumonia. Higher risk of severe disease is experienced by premature infants, infants under 6 months of age, and those with underlying conditions. Young children with weakened immune systems or chronic lung or heart conditions are also at increased risk. Older adults are also at increased risk, with over 100,000 hospitalizations due to RSV in the US each year.

Symptom profiles vary by age.

In very young infants the only symptoms may be irritability, decreased appetite and activity, signs of breathing difficulty, or apnea. Infants needing hospitalization may require oxygen, intubation, and/or mechanical ventilation. Most infants improve with appropriate supportive care and are discharged after a few days.
Adults and older children may have mild cold-like symptoms or be asymptomatic. Those at high risk (persons with chronic illnesses or weakened immune systems) may have symptoms compatible with pneumonia.

Testing:

Hawai’i’s major clinical laboratories have antigen detection tests, as well as RT-PCR assays that can detect RSV infection. The State Laboratories Division of Hawai’i’s Department of Health also has the capability to run a RT-PCR respiratory virus panel batch once a month for cases that occur in outbreaks and clusters that occur in healthcare facilities, daycares, and schools.

Vaccination and Immunization:

Hawai’i DOH recommends year-round administration of maternal RSV vaccination and monoclonal antibody for infants whose mother was not vaccinated during that pregnancy.

Vaccination during pregnancy

Vaccination is routinely recommended between 32 and 36 weeks gestation. The RSV vaccination is only given once, so for future pregnancies the infant should receive an RSV monoclonal antibody. ONLY Abrysvo (Pfizer product) is approved for use during pregnancy

For more details see the ACOG Practice Advisory on Maternal RSV Vaccination and ACOG physician FAQs on Maternal RSV Vaccination.

Immunization of Newborn/Infant with Monoclonal Antibody

Infants younger than 8 months should receive a RSV monoclonal antibody if their mother was not vaccinated during that pregnancy. The younger an infant, the higher the risk of severe illness due to infection with RSV. Therefore, it is recommended to administer RSV antibody within 1 week of birth, ideally during birth hospitalization. However, administration can occur during any health care visit, including well-child visits.

For additional information see the AAP Policy Statement on Prevention of RSV Disease

Anti-RSV monoclonal antibody: currently available products

Nirsevimab (Beyfortus, Sanofi and AstraZeneca)
Clesrovimab (Enflonsia, Merck)

Duration of protection is about 5 months for both products.

*Note: Palivizumab is no longer recommended and production has been discontinued

Vaccination for adults

Hawai’i DOH recommends routine RSV vaccination for all adults 75 years and older and for adults 50-74 years old at increased risk for complications from RSV infection due to chronic health conditions, immune compromise, or residence in a nursing home. Specific indications are listed on the AAFP vaccination schedule.

RSV vaccines approved by the FDA for use in adults 50 years and older:

Arexvy (GSK, adjuvanted) is a monovalent RSVPreF3 adjuvanted, approved in 2023
Abrysvo (Pfizer, no adjuvant) – bivalent RSVPreF recombinant, approved in 2023
Mresvia (Moderna, no adjuvant) – monovalent RSV PreF mRNA, approved in 2024

Last Reviewed: March 2026