Estimating RSV Disease Burden in the United States Brian Rha, MD, MSPH Medical Epidemiologist, Division of Viral Diseases Centers for Disease Control and Prevention Severe Acute Respiratory Infection Surveillance in the Americas (SARInet) Meeting Cancun, Mexico 28 30 April 2015 National Center for Immunization and Respiratory Diseases Division of Viral Diseases
Respiratory Syncytial Virus (RSV) Common cause of acute respiratory infections Most infected in 1 st year of life Virtually all children infected by 2 years of age Repeat infections affect older children and adults Most common cause of lower respiratory tract infections among infants Manifests as bronchiolitis or pneumonia Diagnosis using rapid tests of respiratory specimens Antigen assays Reverse transcriptase-polymerase chain reaction (RT-PCR) assays
Clinical Manifestations Primary Infection Most have upper respiratory tract symptoms 20 30% develop lower respiratory tract disease Bronchiolitis and/or pneumonia Most do not require hospitalization Symptoms: tachypnea, cough, labored breathing, wheezing, crackles Fever may be absent Young infants may present with apnea, irritability, poor feeding Relationship with subsequent development of recurrent wheezing unclear
* http://sites.path.org/vaccinedevelopment/files/2011/12/rsv-snapshot-march2015.pdf
Approaches to Estimating RSV Hospitalization Burden Retrospective analysis of national hospitalization data Hospital discharge data from national survey/insurance databases Estimates often rely on RSV proportions from prospective studies Prospective active population-based surveillance Establishment of surveillance sites to capture cases Denominator data to yield rate information RSV diagnoses based on sensitive diagnostic tests (PCR)
Hospital Discharge Data from National Hospital Discharge Survey (NHDS) US, 1997 2006 Discharge diagnoses codes (ICD-9-CM) All lower respiratory tract illness (LRTI) Children less than 5 years of age RSV-associated hospitalizations All RSV-specific coded hospitalizations year-round 30% of wintertime unspecified acute bronchiolitis 20% of wintertime unspecified pneumonia Average annual hospitalization rates calculated Denominator data from US census data Stratified by age group * Stockman et al. Pediatr Infect Dis J 2012; 31: 5 9
Annual Average RSV-Associated Burden by Age Group <5 years of age: 172,000 RSV-associated hospitalizations <1 year of age: 126,000 RSV-associated hospitalizations (32 per 1000 infants) * Stockman et al. Pediatr Infect Dis J 2012; 31: 5 9
New Vaccine Surveillance Network (NVSN): Acute Respiratory Illness (ARI) Surveillance CDC-sponsored multi-site collaborative project Prospective surveillance for ARI in 2000 2009 Site locations in 3 US counties Rochester, Nashville, and Cincinnati areas Study population: children <5 years of age Inpatient and outpatient settings
NVSN ARI Surveillance: Hospitalized Burden of RSV Enrollment criteria: Children <5 years of age admitted with diagnoses of acute respiratory infection* *Illness presenting with one or more of the following symptoms: Fever, cough, earache, nasal congestion, rhinorrhea, sore throat, vomiting after coughing, wheezing, and labor, rapid or shallow breathing Patients interviewed, had medical records reviewed, and tested for respiratory viral pathogens Nasal and throat swab Hospitalization rates calculated using denominator data US census data Birth certificate data
NVSN ARI Surveillance: Hospitalized Burden of RSV Years Denominator Data Source 2000 2004 1 US Census Age group Months Average annual rate of RSV-associated hospitalization Rate/1000 children (95% CI) <60 3.0 (2.8 3.4) 0 5 16.9 (15.3 18.5) 2000 2005 2 Birth Certificates <24 5.2 (4.8 5.7) 0 2 17.9 (15.7 20.1) 3 5 8.0 (6.6 9.5) 6 11 3.9 (3.2 4.7) 1. Hall et al. N Engl J Med 2009; 360: 588 98 2. Hall et al. Pediatrics 2013; 132:e341 e348
Characteristics of Hospitalized Patients (<5 Years of Age, US 2000 2004) Variable RSV-positive (N = 564) % Age <6 months 58 O 2 supplementation 95 Length of stay (median days) 2 Bronchiolitis discharge diagnosis 70 High risk condition 34 Premature >1 month 16 * Hall et al. N Engl J Med 2009; 360: 588 98
Summary RSV a significant cause of morbidity among children <5 years of age in the US Hospitalization rates highest in young infants Retrospective analysis of national databases can yield useful estimates Population-based surveillance is needed for most accurate estimates of burden Important to assess impact of case definitions
Thank You www.cdc.gov/rsv For more information please contact Centers for Disease Control and Prevention 1600 Clifton Road NE, Atlanta, GA 30333 Telephone: 1-800-CDC-INFO (232-4636)/TTY: 1-888-232-6348 Visit: www.cdc.gov Contact CDC at: 1-800-CDC-INFO or www.cdc.gov/info The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. National Center for Immunization & Respiratory Diseases Division of Viral Diseases