Influenza and respiratory syncytial virus in infants study (IRIS) of hospitalized and non-ill infants aged <1 year in four countries: study design and methods.
This multi-country prospective study of infants aged <1 year aims to assess the frequency of influenza virus and respiratory syncytial virus (RSV) infections associated with hospitalizations, to describe clinical features and antibody response to infection, and to examine predictors of very severe disease requiring intensive care.



We are enrolling a hospital-based cohort and a sample of non-ill infants in four countries (Albania, Jordan, Nicaragua, and the Philippines) using a common protocol. We are currently starting year 2 of a 2- to 3-year study and will enroll approximately 3,000 infants hospitalized for any acute illness (respiratory or non-respiratory) during periods of local influenza and/or RSV circulation. After informed consent and within 24 h of admission, we collect blood and respiratory specimens and conduct an interview to assess socio-demographic characteristics, medical history, and symptoms of acute illness (onset ≤10 days). Vital signs, interventions, and medications are documented daily through medical record abstraction. A follow-up health assessment and collection of convalescent blood occurs 3-5 weeks after enrollment. Influenza and RSV infection is confirmed by singleplex real time reverse transcriptase polymerase chain reaction (rRT-PCR) assays. Serologic conversion will be assessed comparing acute and convalescent sera using hemagglutination inhibition assay for influenza antibodies and enzyme-linked immunosorbent assay (ELISA) for RSV. Concurrent with hospital-based enrollment, respiratory specimens are also being collected (and tested by rRT-PCR) from approximately 1,400 non-ill infants aged <1 year during routine medical or preventive care.



The Influenza and RSV in Infants Study (IRIS) promises to expand our knowledge of the frequency, clinical features, and antibody profiles of serious influenza and RSV disease among infants aged <1 year, quantify the proportion of infections that may be missed by traditional surveillance, and inform decisions about the potential value of existing and new vaccines and other prevention and treatment strategies.
Influenza Division, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA. Isq8@cdc.gov.|Influenza Division, MS A-32, National Center for Immunization and Respiratory Disease, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Atlanta, GA, 30333, USA. Isq8@cdc.gov.
Mark G
MG
Thompson
Abt Associates, Inc, Atlanta, GA, USA.
Danielle R
DR
Hunt
The Eastern Mediterranean Public Health Network (EMPHNET), Amman, Jordan.
Ali K
AK
Arbaji
Department of Epidemiology & Control of Infectious Diseases, Institute of Public Health, Tirana, Albania.
Artan
A
Simaku
Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Metro Manila, Philippines.
Veronica L
VL
Tallo
Division of Viral Diseases, CDC, Atlanta, GA, USA.
Holly M
HM
Biggs
Abt Associates, Inc, Atlanta, GA, USA.
Carolyn
C
Kulb
Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA.
Aubree
A
Gordon
The Eastern Mediterranean Public Health Network (EMPHNET), Amman, Jordan.
Ilham Abu
IA
Khader
Department of Epidemiology & Control of Infectious Diseases, Institute of Public Health, Tirana, Albania.
Silvia
S
Bino
Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Metro Manila, Philippines.
Marilla G
MG
Lucero
Influenza Division, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA.
Eduardo
E
Azziz-Baumgartner
Abt Associates, Inc, Atlanta, GA, USA.
Pat
P
Shifflett
Hospital Infantil Manuel de Jesús Rivera, Ministry of Health, Managua, Nicaragua.
Felix
F
Sanchez
Al-Bashir Hospital, Amman, Jordan.
Basima I
BI
Marar
Pediatric Hospital, University Hospital Centre, Tirana, Albania.
Ilirjana
I
Bakalli
Section of Infectious Diseases, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.|Center for Global Health, Department of Epidemiology, Colorado School of Public Health, Aurora, Colorado, USA.
Eric A F
EA
Simões
Influenza Division, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA.
Min Z
MZ
Levine
Marshfield Clinic Research Foundation, Marshfield, WI, USA.
Jennifer K
JK
Meece
Laboratorio Nacional de Virología, Centro Nacional de Diagnóstico y Referencia, Ministry of Health, Managua, Nicaragua.
Angel
A
Balmaseda
The Eastern Mediterranean Public Health Network (EMPHNET), Amman, Jordan.
Tareq M
TM
Al-Sanouri
Department of Epidemiology & Control of Infectious Diseases, Virology Laboratory, Institute of Public Health, Tirana, Albania.
Majlinda
M
Dhimolea
Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Metro Manila, Philippines.
Joanne N
JN
de Jesus
Division of Viral Diseases, CDC, Atlanta, GA, USA.
Natalie J
NJ
Thornburg
Division of Viral Diseases, CDC, Atlanta, GA, USA.
Susan I
SI
Gerber
Sustainable Sciences Institute, Managua, Nicaragua.
Lionel
L
Gresh
D000415:Albania / Q000453:epidemiology; D000914:Antibodies, Viral; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology*; D007597:Jordan / Q000453:epidemiology; D008297:Male; D009527:Nicaragua / Q000453:epidemiology; D010679:Philippines / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis / Q000453:epidemiology*; D018113:Respiratory Syncytial Virus, Human / Q000302:isolation & purification*; D012136:Respiratory Syncytial Viruses; D012307:Risk Factors
D000914:Antibodies, Viral
Burden; Hospital; Infant; Influenza; Respiratory syncytial virus; Serology