Surveillance of RSV

Surveillance and research systems

CDC has several systems that focus on monitoring and describing seasonal trends, clinical risk factors, rates of illness and hospitalization, and demographics of patients seeking care for illness associated with respiratory syncytial virus (RSV).

• The National Respiratory and Enteric Virus Surveillance System (NREVSS) is a laboratory-based system that monitors seasons and circulation patterns of RSV and other viruses.
• The National Syndromic Surveillance Program (NSSP) is a collaboration among CDC, federal partners, state and local health departments, and academic and private sector partners to collect, analyze, and share electronic data received from emergency departments and other health care settings.
• The RSV Hospitalization Surveillance Network (RSV-NET) is a population-based surveillance system for RSV-associated hospitalizations in the U.S. among children and adults.
• The New Vaccine Surveillance Network (NVSN) is a multisite, active, population-based pediatric surveillance network for acute respiratory hospitalizations and outpatient visits associated with RSV and other respiratory pathogens.
• The Investigating Respiratory Viruses in the Acutely Ill (IVY) Network is a multisite, active surveillance network designed to assess how well vaccines work to prevent COVID-19, flu, and RSV-associated hospitalizations among adults.
• The RSV Surveillance in Native American Persons (RSV SuNA) collaboration monitors for RSV-associated hospitalizations and outpatient visits among Alaska Native and American Indian persons and is conducted on the Navajo Nation, White Mountain Apache Tribal Lands, and in Alaska. Additional information about other research and surveillance activities among Alaska Native persons may be provided by the Arctic Investigations Program.

RSV burden estimates

Each year in the United States, RSV leads to approximately:

• 2.1 million outpatient (non-hospitalization) visits among children younger than 5 years old.
  
• 58,000–80,000 hospitalizations among children younger than 5 years old.
  
• 100,000–150,000 hospitalizations among adults 60 years and older.
  

RSV seasonal trends

How are data collected?

CDC collects RSV laboratory test results performed in the United States using the National Respiratory and Enteric Virus Surveillance System (NREVSS). CDC analyzes data on RSV activity at the national, regional, and state levels. NREVSS is a voluntary, laboratory-based surveillance system established in the 1980s to monitor seasonal trends of several viruses, including RSV. Through NREVSS, participating laboratories report the total number of weekly RSV tests performed to detect the virus and the number of those tests that were positive. Data from NREVSS provide information to public health officials and healthcare providers about the presence of RSV in their communities.

What are the typical seasonal patterns?

In most regions of the United States and other areas with similar climates, the RSV season typically starts during the fall and peaks in the winter. Based on data from before the COVID-19 pandemic (2014 to 2017), in all 10 U.S. Department of Health and Human Services (HHS) regions, except Florida and Hawaii, these patterns were observed:

• RSV season onset (indicated by a sustained increase in the percent positivity of RSV tests above a threshold) ranged from mid-September to mid-November.
• RSV season peak (indicated by the maximum in percent positivity of RSV tests) ranged from late December to mid-February.
• RSV season offset (indicated by a sustained decrease in the percent positivity of RSV tests below a threshold) ranged from mid-April to mid-May.

Florida has an earlier RSV season onset and longer duration than most regions of the country.