For Healthcare Providers

Respiratory syncytial virus (RSV) is recognized as one of the most common causes of childhood illness and is the most common cause of hospitalization in infants. It causes annual outbreaks of respiratory illnesses in all age groups. In most regions of the United States, RSV season starts in the fall and peaks in the winter, but the timing and severity of RSV season in a given community can vary from year to year.

Healthcare providers should consider RSV in patients with respiratory illness, particularly during the RSV season. For more information about recommended infection prevention and control practices in healthcare settings, see CDC’s 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings.

RSV Vaccines are available to protect older adults from severe RSV. Monoclonal antibody products are available to protect infants and young children from severe RSV. A healthcare provider’s recommendation is one of the most important factors in whether patients choose to accept a new prevention product or vaccine.

Vaccines for Older Adults

New vaccines against RSV are available for adults 60 and older. CDC recommends that adults 60 and older may receive an RSV vaccine, using shared clinical decision-making. The decision to vaccinate an individual patient should be based on a discussion between the healthcare provider and the patient. It may be informed by the patient’s risk of severe RSV disease and their characteristics, values, and preferences; the healthcare provider’s clinical discretion; and the characteristics of the vaccine.

Healthcare providers should be aware of underlying conditions that may increase the risk of severe RSV illness, and who might be most likely to benefit from these new vaccines.

RSV vaccine is recommended as a single dose. Studies are ongoing to determine whether (and if so, when) revaccination may be needed.

Monoclonal Antibody Products for Infants and Young Children

Nirsevimab (Beyfortus) is a monoclonal antibody product designed to protect infants and young children at increased risk from severe RSV disease. It is administered by intramuscular injection. It is long-acting, providing protection for at least 5 months (the average length of one season), and only one dose is recommended for an RSV season. However, immune protection will wane over time. All infants younger than 8 months who are born during – or entering – their first RSV season should receive one dose of nirsevimab. For some children between the ages of 8 and 19 months who are at increased risk of severe RSV disease, a dose is recommended at the start of their second RSV season.

Palivizumab (Synagis) is a monoclonal antibody product recommended by the American Academy of Pediatrics (AAP) for administration to infants and young children who are at increased risk of severe RSV disease based on gestational age and certain underlying medical conditions. It is given in monthly intramuscular injections during RSV season. For the latest palivizumab guidance, please consult the AAP policy statement. An accompanying AAP technical report provides additional context and rationale for the guidance. Interim guidance addressing the disruption in typical RSV seasonal patterns during the pandemic has also been provided: Updated Guidance: Use of Palivizumab Prophylaxis to Prevent Hospitalization From Severe Respiratory Syncytial Virus Infection During the 2022-2023 RSV Season (aap.org)

Clinical Description and Diagnosis

In Infants and Young Children

RSV infection can cause a variety of respiratory illnesses and symptoms in infants and young children. It most commonly causes a cold-like illness but can also cause lower respiratory infections like bronchiolitis and pneumonia. Two to three percent of infants with RSV infection may need to be hospitalized. Severe disease most commonly occurs in very young infants. Additionally, children with any of the following underlying conditions are considered at increased risk:

• Premature infants
• Infants, especially those 6 months and younger
• Children younger than 2 years old with chronic lung disease or congenital heart disease
• Children with suppressed or weakened immune systems
• Children who have neuromuscular disorders or a congenital anomaly, including those who have difficulty swallowing or clearing mucus secretions
• Children with severe cystic fibrosis

Infants and young children with RSV infection may have rhinorrhea and a decrease in appetite before any other symptoms appear. Cough usually develops 1 to 3 days later. Soon after the cough develops, sneezing, fever, and wheezing may occur. Symptoms in very young infants can include irritability, decreased activity, and/or apnea.

Most otherwise healthy infants and young children who are infected with RSV do not need hospitalization. Those who are hospitalized may require oxygen, rehydration, and/or mechanical ventilation. Most improve with supportive care and are discharged in a few days.

In Older Adults and Adults with Chronic Medical Conditions

Adults who get infected with RSV usually have mild or no symptoms. Symptoms are usually consistent with an upper respiratory tract infection which can include rhinorrhea, pharyngitis, cough, headache, fatigue, and fever. Disease usually lasts less than 5 days.

Some adults, however, may have more severe symptoms consistent with a lower respiratory tract infection, such as pneumonia. Epidemiologic evidence indicates that people 60 and older who are at highest risk of severe RSV disease include those with any of the following chronic conditions:

• Lung disease (such as chronic obstructive pulmonary disease [COPD] and asthma)
• Chronic cardiovascular diseases (such as congestive heart failure and coronary artery disease)
• Diabetes mellitus
• Neurologic conditions
• Kidney disorders
• Liver disorders
• Hematologic disorders
• Immune compromise
• Other underlying conditions that a health care provider determines might increase the risk for severe respiratory disease

Other underlying factors that the provider determines might increase the risk of severe RSV-associated respiratory illness may include the following:

• Frailty
• Advanced age
• Residence in a nursing home or other long-term care facility
• Other underlying factors that a health care provider determines might increase the risk for severe respiratory disease

RSV can sometimes also lead to exacerbation of serious conditions such as:

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Congestive heart failure

Clinical Laboratory Testing

Clinical symptoms of RSV are nonspecific and can overlap with other viral respiratory infections, as well as some bacterial infections. Several types of laboratory tests are available for confirming RSV infection. These tests may be performed on upper and lower respiratory specimens.

The most commonly used types of RSV clinical laboratory tests are

• Real-time reverse transcription-polymerase chain reaction (rRT-PCR), which is more sensitive than culture and antigen testing
• Antigen testing, which is sensitive in children but less sensitive in adults

Less commonly used tests include:

• Viral culture
• Serology, which is usually only used for research and surveillance studies

Some tests can differentiate between RSV subtypes (A and B), but the clinical significance of these subtypes is unclear. Consult your laboratorian for information on what type of respiratory specimen is most appropriate to use.

For Infants and Young Children

Both rRT-PCR and antigen detection tests are effective methods for diagnosing RSV infection in infants and young children. The sensitivity of RSV antigen detection tests generally ranges from 80% to 90% in this age group. Healthcare providers should consult experienced laboratorians for more information on interpretation of results.

For Older Children, Adolescents, and Adults

Healthcare providers should use highly sensitive rRT-PCR assays when testing older children and adults for RSV. rRT-PCR assays are now commercially available for RSV. The sensitivity of these assays often exceeds the sensitivity of virus isolation and antigen detection methods. Antigen tests are not sensitive for older children and adults because they may have lower viral loads in their respiratory specimens. Healthcare providers should consult experienced laboratorians for more information on interpretation of results.