Overview of Viral Respiratory Infections

• Usually history and physical examination and local epidemiology

• Sometimes diagnostic testing

Viral respiratory infections are typically diagnosed clinically based on symptoms and local epidemiology. For patient care, diagnosing the syndrome is usually sufficient; identification of a specific pathogen is rarely necessary.

Diagnostic testing should be reserved for the following:

• Situations in which knowing the specific pathogen affects clinical management

• Epidemiologic surveillance (ie, identifying and determining the cause of an outbreak)

Pathogen identification can be important when specific antiviral therapy is indicated. Antiviral therapy is given for the following viruses and indications:

• Influenza: Patients or close contacts of patients at high risk of complications; may be given to average-risk patients with symptoms for < 48 hours (1)

• COVID-19: Patients at high risk of severe disease with symptoms for < 5 days (2)

• RSV infection: Severely immunocompromised patients

Identifying the specific pathogen (particularly the influenza virus or RSV in hospitalized patients or patients residing in a facility) may also be important for infection prevention and control, including identifying and containing potential outbreaks.

Rapid point-of-care antigen-based and polymerase chain reaction (PCR)-based diagnostic tests are available for influenza, RSV, and SARS-CoV-2. The rapid point-of-care antigen-based tests have lower sensitivity than PCR-based laboratory tests (3). Point-of-care tests are typically reserved for cases when clinical diagnosis is uncertain and

• Antiviral therapy is being considered.

• Identification of the viral pathogen would prevent additional evaluation for or treatment of a bacterial infection.

• Identification of the viral pathogen would aid in infection prevention and control in the inpatient setting.

PCR-based detection of viral pathogens in a multiplex panel (or individually for influenza, RSV, and SARS-CoV-2) is available in many clinical laboratories. These tests are more sensitive than antigen-based point-of-care tests and, when available, are preferred for clinical purposes.

Cell culture or serologic tests are sometimes available but are slower than PCR tests. They may be useful for epidemiologic surveillance.

• Supportive

• Sometimes antiviral medications

Treatment of viral respiratory infections is usually supportive.

Antibacterial medications are ineffective against viral pathogens, and prophylaxis against secondary bacterial infections is not recommended. Antibiotics should be given only when secondary bacterial infections develop.

≤ 18 years with a suspected viral respiratory tract infection, because Reye syndrome is a risk.

Some patients continue to cough for 3 to 8 weeks after resolution of an upper respiratory infection (1); these symptoms may lessen with use of an inhaled bronchodilator or corticosteroids.

In some cases, antiviral medications are useful:

• 2).

• 3).

• 4).

• prevent RSV infection in infants and young children (5, 6, 7). (Nirsevimab is preferred but may not be available to some infants; if it is not available, eligible high-risk infants and children should receive palivizumab.)