RSV Research & Surveillance
CDC has several research and surveillance platforms that focus on seasonal trends, clinical risk factors, rates, and demographics of patients seeking care for RSV-associated illness.
- The RSV Hospitalization Surveillance Network (RSV-NET) is a population-based surveillance system that monitors respiratory syncytial virus hospitalizations in the US among children and adults.
- The National Respiratory and Enteric Virus Surveillance System (NREVSS) is a laboratory-based system that monitors temporal and geographic circulation patterns (patterns occurring in time and place) of respiratory syncytial virus (RSV) and other viral infections.
- The New Vaccine Surveillance Network (NVSN) is a multisite, active, population-based surveillance network for hospitalizations and outpatient visits among children that are associated with RSV and other acute respiratory illnesses.
- The Influenza and Other Viruses in the Acutely Ill (IVY) network is a multisite, active surveillance network designed to assess how well vaccines work to prevent severe COVID-19, flu, and eventually RSV-associated hospitalizations among adults.
- The Surveillance in Native Americans (SuNA) collaboration monitors for RSV-associated hospitalizations and outpatient visits among Native American 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.
Each year in the United States, RSV leads to approximately:
- 2.1 million outpatient (non-hospitalization) visits among children younger than 5 years old.(1)
- 58,000-80,000 hospitalizations among children younger than 5 years old.(2,3)
- 60,000-120,000 hospitalizations among adults 65 years and older.(4,5)
- 6,000-10,000 deaths among adults 65 years and older.(6,7)
- 100–300 deaths in children younger than 5 years old.(7)
How are data collected?
CDC collects RSV laboratory test results performed in the United States using a surveillance system called the National Respiratory and Enteric Virus Surveillance System (NREVSS). CDC analyzes data on RSV activity at the national, regional, and state levels and RSV Surveillance Reports are periodically published. This is a voluntary, laboratory-based surveillance system established in the 1980s to monitor trends in 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. They also report the method used for detection, and the location and date of specimen collection. Serotyping, demographic data, and clinical data are not reported. Data from NREVSS provides information to public health officials and healthcare providers about the presence of RSV in their communities.
What are the seasonal patterns?
In the United States and other areas with similar climates, RSV circulation generally starts during the fall and peaks in the winter. From 2014 to 2017 in all 10 U.S. Department of Health and Human Services (HHS) regions, except Florida and Hawaii(8):
- RSV season onset (indicating a sustained rise in the number of RSV-positive tests) ranged from mid-September to mid-November.
- RSV season peak (indicating the maximum number of RSV-positive tests) ranged from late December to mid-February.
- RSV season offset (indicating a sustained drop in the number of RSV-positive tests) ranged from mid-April to mid-May.
Florida has an earlier RSV season onset and longer duration than most regions of the country.
Prior to 2020, seasonal patterns for RSV in the United States were very consistent.(8) However, the patterns of circulation for RSV and other common respiratory viruses have been disrupted since the start of the COVID-19 pandemic early in 2020. Beginning in the southern region of the United States, RSV circulation began to rise in the spring months of 2021 and peaked in July.(9) It is too soon to predict when the previous seasonal patterns will return.
- Hall CB, Weinberg GA, Iwane MK, et al. The burden of respiratory syncytial virus infection in young children. New Engl J Med. 2009;360(6):588–98.
- Rha B, Curns AT, Lively JY, et al. Respiratory Syncytial Virus–Associated Hospitalizations Among Young Children: 2015–2016. Pediatrics. 2020;146(1):e20193611.
- McLaughlin JM, Khan F, Schmitt H-J, et al. Respiratory Syncytial Virus–Associated Hospitalization Rates among US Infants: A Systematic Review and Meta-Analysis. JID. 2022;225(6):1100-1111.
- McLaughlin JM, Khan F, Begier E, et al. Rates of Medically Attended RSV among US Adults: A Systematic Review and Meta-analysis. Open Forum Infect Dis. 2022; 9(7): ofac300.
- CDC unpublished data from RSV-NET. Available at: www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-10-19-20/04-RSV-Adults-Melgar-508.pdf.
- Thompson WW, Shay DK, Weintraub E, et al. Mortality Associated with Influenza and Respiratory Syncytial Virus in the United States. JAMA. 2003; 289(2): 179.186
- Hansen CL, Chaves SS, Demont C, Viboud C. Mortality Associated With Influenza and Respiratory Syncytial Virus in the US, 1999-2018. JAMA Network Open. 2022 Feb 1;5(2):e220527.
- Centers for Disease Control and Prevention. Respiratory Syncytial Virus Seasonality — United States, 2014–2017. MMWR. 2018;67(2):71–76.
- Centers for Disease Control and Prevention. Changes in Influenza and Other Respiratory Virus Activity During the COVID-19 Pandemic — United States, 2020–2021. MMWR. 2021;70(29):1013–1019.